Amoxicillin is an

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

medication belonging to the

aminopenicillin The aminopenicillins are a group of antibiotics in the penicillin family that are structural analogs of ampicillin (which is the 2-amino derivative of benzylpenicillin, hence the name). Like other penicillins and beta-lactam antibiotics, they con ...

class of the

penicillin Penicillins (P, PCN or PEN) are a group of beta-lactam antibiotic, β-lactam antibiotics originally obtained from ''Penicillium'' Mold (fungus), moulds, principally ''Penicillium chrysogenum, P. chrysogenum'' and ''Penicillium rubens, P. ru ...

family. The drug is used to treat

bacterial infection Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and many are beneficial but others can cause infectious diseases. The number of t ...

s such as middle ear infection,

strep throat Streptococcal pharyngitis, also known as streptococcal sore throat (strep throat), is pharyngitis (an infection of the pharynx, the back of the throat) caused by ''Streptococcus pyogenes'', a Gram-positive bacteria, gram-positive, group A str ...

pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

, skin infections, odontogenic infections, and

urinary tract infection A urinary tract infection (UTI) is an infection that affects a part of the urinary tract. Lower urinary tract infections may involve the bladder (cystitis) or urethra (urethritis) while upper urinary tract infections affect the kidney (pyel ...

s. It is taken orally (swallowed by mouth), or less commonly by either

intramuscular injection Intramuscular injection, often abbreviated IM, is the medical injection, injection of a substance into a muscle. In medicine, it is one of several methods for parenteral, parenteral administration of medications. Intramuscular injection may be ...

or by an IV bolus injection, which is a relatively quick

intravenous injection Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutr ...

lasting from a couple of seconds to a few minutes. Common adverse effects include nausea and rash. It may also increase the risk of

yeast infections Candidiasis is a fungal infection due to any species of the genus '' Candida'' (a yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the ...

and, when used in combination with

clavulanic acid Clavulanic acid is a β-lactam antibiotic, β-lactam drug that functions as a Suicide inhibition, mechanism-based β-lactamase inhibitor. While not effective by itself as an antibiotic, when combined with penicillin-group antibiotics, it can ove ...

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

. It should not be used in those who are allergic to

. While usable in those with kidney problems, the dose may need to be decreased. Its use in

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

and

breastfeeding Breastfeeding, also known as nursing, is the process where breast milk is fed to a child. Infants may suck the milk directly from the breast, or milk may be extracted with a Breast pump, pump and then fed to the infant. The World Health Orga ...

does not appear to be harmful. Amoxicillin is in the β-lactam family of antibiotics. Amoxicillin was discovered in 1958 and came into medical use in 1972. Amoxil was approved for medical use in the United States in 1974, and in the United Kingdom in 1977. It is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...

. It is one of the most commonly prescribed antibiotics in children. Amoxicillin is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

. In 2022, it was the 26th most commonly prescribed medication in the United States, with more than 20million prescriptions.

Medical uses

Amoxicillin is used in the treatment of a number of infections, including acute otitis media,

streptococcal pharyngitis Streptococcal pharyngitis, also known as streptococcal sore throat (strep throat), is pharyngitis (an infection of the pharynx, the back of the throat) caused by '' Streptococcus pyogenes'', a gram-positive, group A streptococcus. Common sy ...

, skin infections,

s, ''

Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...

'' infections,

Lyme disease Lyme disease, also known as Lyme borreliosis, is a tick-borne disease caused by species of ''Borrelia'' bacteria, Disease vector, transmitted by blood-feeding ticks in the genus ''Ixodes''. It is the most common disease spread by ticks in th ...

, and

chlamydia Chlamydia, or more specifically a chlamydia infection, is a sexually transmitted infection caused by the bacterium ''Chlamydia trachomatis''. Most people who are infected have no symptoms. When symptoms do appear, they may occur only several w ...

infections.

Acute otitis media

Children with acute otitis media who are younger than six months of age are generally treated with amoxicillin or other antibiotics. Although most children with acute otitis media who are older than two years old do not benefit from treatment with amoxicillin or other antibiotics, such treatment may be helpful in children younger than two years old with acute otitis media that is bilateral or accompanied by ear drainage. In the past, amoxicillin was dosed three times daily when used to treat acute otitis media, which resulted in missed doses in routine ambulatory practice. There is now evidence that two-times daily dosing or once-daily dosing has similar effectiveness.

Respiratory infections

Most sinusitis infections are caused by

virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...

es, for which amoxicillin and amoxicillin-clavulanate are ineffective, and the small benefit gained by amoxicillin may be overridden by the adverse effects. Amoxicillin is considered the first-line empirical treatment for most cases of uncomplicated bacterial sinusitis in children and adults when culture data is unavailable. Amoxicillin is recommended as the preferred first-line treatment for community-acquired pneumonia in adults by the

National Institute for Health and Care Excellence The National Institute for Health and Care Excellence (NICE) is an executive non-departmental public body of the Department of Health and Social Care (United Kingdom), Department of Health and Social Care. As the national health technolog ...

, either alone (mild to moderate severity disease) or in combination with a

macrolide Macrolides are a class of mostly natural products with a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. Macrolides belong to the polyketide class of natural products. ...

. Research suggests that is as effective as co-amoxiclav (a broad-spectrum antibiotic) for people admitted to hospital with pneumonia, regardless of its severity. The

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

(WHO) recommends amoxicillin as first-line treatment for pneumonia that is not "severe". Amoxicillin is used in post-exposure inhalation of

anthrax Anthrax is an infection caused by the bacterium '' Bacillus anthracis'' or ''Bacillus cereus'' biovar ''anthracis''. Infection typically occurs by contact with the skin, inhalation, or intestinal absorption. Symptom onset occurs between one ...

to prevent disease progression and for prophylaxis.

''H. pylori''

It is effective as one part of a multi-drug regimen for the treatment of stomach infections of ''

Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, Flagellum#bacterial, flagellated, Bacterial cellular morphologies#Helical, helical bacterium. Mutants can have a rod or curved rod shape that exhibits l ...

''. It is typically combined with a

proton-pump inhibitor Proton-pump inhibitors (PPIs) are a class of medications that cause a profound and prolonged reduction of gastric acid, stomach acid production. They do so by irreversibly inhibiting the stomach's H+/K+ ATPase, H+/K+ ATPase proton pump. The body ...

(such as

omeprazole Omeprazole, sold under the brand names Prilosec and Losec, among others, is a medication used in the treatment of gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger–Ellison syndrome. It is also used to prevent up ...

) and a macrolide antibiotic (such as

clarithromycin Clarithromycin, sold under the brand name Biaxin among others, is an antibiotic used to treat various bacterial infections. This includes strep throat, pneumonia, skin infections, '' H. pylori'' infection, and Lyme disease, among others. Clari ...

); other drug combinations are also effective.

Lyme borreliosis

Amoxicillin is effective for the treatment of early cutaneous Lyme borreliosis; the effectiveness and safety of oral amoxicillin is neither better nor worse than common alternatively-used antibiotics.

Odontogenic infections

Amoxicillin is used to treat odontogenic infections, infections of the tongue, lips, and other oral tissues. It may be prescribed following a

tooth extraction A dental extraction (also referred to as tooth extraction, exodontia, exodontics, or informally, tooth pulling) is the removal of teeth from the dental alveolus (socket) in the alveolar bone. Extractions are performed for a wide variety of reas ...

, particularly in those with compromised immune systems.

Skin infections

Amoxicillin is occasionally used for the treatment of skin infections, such as

acne vulgaris Acne ( ), also known as ''acne vulgaris'', is a long-term Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, ...

. It is often an effective treatment for cases of acne vulgaris that have responded poorly to other antibiotics, such as

doxycycline Doxycycline is a Broad-spectrum antibiotic, broad-spectrum antibiotic of the Tetracycline antibiotics, tetracycline class used in the treatment of infections caused by bacteria and certain parasites. It is used to treat pneumonia, bacterial p ...

and

minocycline Minocycline, sold under the brand name Minocin among others, is a tetracycline antibiotic medication used to treat a number of bacterial infections such as some occurring in certain forms of pneumonia. It is generally (but not always) less pre ...

Infections in infants in resource-limited settings

Amoxicillin is recommended by the World Health Organization for the treatment of

infant In common terminology, a baby is the very young offspring of adult human beings, while infant (from the Latin word ''infans'', meaning 'baby' or 'child') is a formal or specialised synonym. The terms may also be used to refer to juveniles of ...

s with signs and symptoms of pneumonia in resource-limited situations when the parents are unable or unwilling to accept hospitalization of the child. Amoxicillin in combination with

gentamicin Gentamicin is an aminoglycoside antibiotic used to treat several types of bacterial infections. This may include bone infections, endocarditis, pelvic inflammatory disease, meningitis, pneumonia, urinary tract infections, and sepsis amo ...

is recommended for the treatment of infants with signs of other severe infections when hospitalization is not an option.

Prevention of bacterial endocarditis

It is also used to prevent

bacterial endocarditis Infective endocarditis is an infection of the inner surface of the heart (endocardium), usually the valves. Signs and symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cell count. ...

and as a pain-reliever in high-risk people having dental work done, to prevent ''

Streptococcus pneumoniae ''Streptococcus pneumoniae'', or pneumococcus, is a Gram-positive, spherical bacteria, hemolysis (microbiology), alpha-hemolytic member of the genus ''Streptococcus''. ''S. pneumoniae'' cells are usually found in pairs (diplococci) and do not f ...

'' and other encapsulated bacterial infections in those without

spleen The spleen (, from Ancient Greek '' σπλήν'', splḗn) is an organ (biology), organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The spleen plays important roles in reg ...

s, such as people with

sickle-cell disease Sickle cell disease (SCD), also simply called sickle cell, is a group of inherited haemoglobin-related blood disorders. The most common type is known as sickle cell anemia. Sickle cell anemia results in an abnormality in the oxygen-carrying ...

, and for both the prevention and the treatment of

. The United Kingdom recommends against its use for infectious endocarditis prophylaxis. These recommendations do not appear to have changed the rates of infection for infectious endocarditis.

Combination treatment

Amoxicillin is susceptible to degradation by

β-lactamase Beta-lactamases (β-lactamases) are enzymes () produced by bacteria that provide Multiple drug resistance, multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams and carbapenems (ertapenem ...

-producing bacteria, which are resistant to most β-lactam antibiotics, such as

. For this reason, it may be combined with

, a

β-lactamase inhibitor Beta-lactamases are a family of enzymes involved in bacterial antimicrobial resistance, resistance to β-lactam antibiotic, beta-lactam antibiotics. In bacterial resistance to beta-lactam antibiotics, the bacteria have beta-lactamase which degra ...

. This drug combination is commonly called co-amoxiclav.

Spectrum of activity

It is a moderate-spectrum, bacteriolytic, β-lactam antibiotic in the

family used to treat susceptible

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is ...

and

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

bacteria. It is usually the drug of choice within the class because it is better absorbed, following oral administration, than other β-lactam antibiotics. In general, ''

Streptococcus ''Streptococcus'' is a genus of gram-positive spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs along a sing ...

Bacillus subtilis ''Bacillus subtilis'' (), known also as the hay bacillus or grass bacillus, is a gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacill ...

Enterococcus ''Enterococcus'' is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are Gram-positive cocci that often occur in pairs ( diplococci) or short chains, and are difficult to distinguish from streptococci on physical ch ...

, Haemophilus,

Helicobacter ''Helicobacter'' is a genus of gram-negative bacteria possessing a characteristic helical shape. They were initially considered to be members of the genus '' Campylobacter'', but in 1989, Goodwin ''et al.'' published sufficient reasons to justi ...

,'' and ''

Moraxella ''Moraxella'' is a genus of gram-negative bacteria in the family Moraxellaceae. It is named after the Swiss ophthalmologist Victor Morax. The organisms are short rods, coccobacilli, or as in the case of '' Moraxella catarrhalis'', diplococci ...

'' are susceptible to amoxicillin, whereas ''

Citrobacter ''Citrobacter'' is a genus of Gram-negative, aerobic, rod-shaped coliform bacteria of the Enterobacteriaceae family. ''Citrobacter'' spp. cause opportunistic infections (including urinary tract infections, gastroenteritis, and bacteremia). ...

Klebsiella ''Klebsiella'' is a genus of Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule. ''Klebsiella'' is named after German-Swiss microbiologist Edwin Klebs (1834–1913). Carl Friedlander described ' ...

'' and ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common Bacterial capsule, encapsulated, Gram-negative bacteria, Gram-negative, Aerobic organism, aerobic–facultative anaerobe, facultatively anaerobic, Bacillus (shape), rod-shaped bacteria, bacterium that can c ...

'' are resistant to it. Some ''

E. coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escherichia'' that is commonly foun ...

'' and most clinical strains of ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often posi ...

'' have developed resistance to amoxicillin to varying degrees.

Adverse effects

Adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term compli ...

s are similar to those for other β-lactam antibiotics, including

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

vomiting Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pre ...

rash A rash is a change of the skin that affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracke ...

es, and antibiotic-associated

colitis Colitis is swelling or inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and ...

Diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

(loose bowel movements) may also occur. Rarer adverse effects include mental and behavioral changes,

lightheadedness Lightheadedness is a common and typically unpleasant sensation of dizziness or a feeling that one may faint. The sensation of lightheadedness can be short-lived, prolonged, or, rarely, recurring. In addition to dizziness, the individual may fee ...

insomnia Insomnia, also known as sleeplessness, is a sleep disorder where people have difficulty sleeping. They may have difficulty falling asleep, or staying asleep for as long as desired. Insomnia is typically followed by daytime sleepiness, low ene ...

hyperactivity Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple ...

, agitation,

confusion In psychology, confusion is the quality or emotional state of being bewildered or unclear. The term "acute mental confusion"

anxiety Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...

, sensitivity to lights and sounds, and unclear thinking. Immediate medical care is required upon the first signs of these adverse effects. Similarly to other penicillins, amoxicillin has been associated with an increased risk of

seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...

s. Amoxicillin-induced

neurotoxicity Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specifical ...

has been especially associated with concentrations of greater than 110mg/L. The onset of an

allergic reaction Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allergy, food al ...

to amoxicillin can be very sudden and intense; emergency medical attention must be sought as quickly as possible. The initial phase of such a reaction often starts with a change in mental state, skin rash with intense itching (often beginning in the fingertips and around the groin area and rapidly spreading), and sensations of fever, nausea, and vomiting. Any other symptoms that seem even remotely suspicious must be taken very seriously. However, more mild allergy symptoms, such as a rash, can occur at any time during treatment, even up to a week after treatment has ceased. For some people allergic to amoxicillin, the adverse effects can be fatal due to

anaphylaxis Anaphylaxis (Greek: 'up' + 'guarding') is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site. It typicall ...

. Use of the amoxicillin/clavulanic acid combination for more than one week has caused a drug-induced immunoallergic-type

hepatitis Hepatitis is inflammation of the liver parenchyma, liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes (jaundice), Anorexia (symptom), poor appetite ...

in some patients. Young children having ingested acute overdoses of amoxicillin manifested

lethargy Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overw ...

, vomiting, and renal dysfunction. There is poor reporting of adverse effects of amoxicillin from clinical trials. For this reason, the severity and frequency of adverse effects from amoxicillin are probably higher than reported in clinical trials.

Nonallergic rash

Between 3 and 10% of children taking amoxicillin (or

ampicillin Ampicillin is an antibiotic belonging to the aminopenicillin class of the penicillin family. The drug is used to prevent and treat several bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, s ...

) show a late-developing (>72 hours after beginning medication and having never taken penicillin-like medication previously) rash, which is sometimes referred to as the "amoxicillin rash". The rash can also occur in adults and may rarely be a component of the

DRESS syndrome Drug rash with eosinophilia and systemic symptoms or drug reaction with eosinophilia and systemic symptoms (DRESS), also termed drug-induced hypersensitivity syndrome (DIHS), is a rare reaction to certain medications. It involves primarily a wi ...

. The rash is described as

maculopapular A maculopapular rash is a type of rash characterized by a flat, red area on the skin that is covered with small confluent bumps. It may only appear red in lighter-skinned people. The term "maculopapular" is a compound: '' macules'' are small, fla ...

or morbilliform ( measles-like; therefore, in medical literature, it is called "amoxicillin-induced morbilliform rash".). It starts on the trunk and can spread from there. This rash is unlikely to be a true allergic reaction and is not a contraindication for future amoxicillin usage, nor should the current regimen necessarily be stopped. However, this common amoxicillin rash and a dangerous allergic reaction cannot easily be distinguished by inexperienced persons, so a healthcare professional is often required to distinguish between the two. A nonallergic amoxicillin rash may also be an indicator of

infectious mononucleosis Infectious mononucleosis (IM, mono), also known as glandular fever, is an infection usually caused by the Epstein–Barr virus (EBV). Most people are infected by the virus as children, when the disease produces few or no symptoms. In young adu ...

. Some studies indicate about 80–90% of patients with acute

Epstein–Barr virus The Epstein–Barr virus (EBV), also known as human herpesvirus 4 (HHV-4), is one of the nine known Herpesviridae#Human herpesvirus types, human herpesvirus types in the Herpesviridae, herpes family, and is one of the most common viruses in ...

infection treated with amoxicillin or ampicillin develop such a rash. Image:Amoxicillin rash 3 hours after 17th dose.JPG, Nonallergic amoxicillin rash eight days after first dose: This photo was taken 24 hours after the rash began. Image:Amoxicillin rash 11 hours after 17th dose.JPG, Eight hours after the first photo, individual spots have grown and begun to merge. Image:Amoxicillin rash 26 hours after 17th dose.JPG, At 23 hours after the first photo, the color appears to be fading, and much of rash has spread to confluence.

Interactions

Amoxicillin may interact with these drugs: *

Anticoagulants An anticoagulant, commonly known as a blood thinner, is a chemical substance that prevents or reduces the coagulation of blood, prolonging the clotting time. Some occur naturally in blood-eating animals, such as leeches and mosquitoes, which h ...

(

dabigatran Dabigatran, sold under the brand name Pradaxa among others, is an anticoagulant used to treat and prevent blood clots and to prevent stroke in people with atrial fibrillation. It is commonly used to prevent blood clots following hip or kn ...

warfarin Warfarin, sold under the brand name Coumadin among others. It is used as an anticoagulant, anticoagulant medication. It is commonly used to prevent deep vein thrombosis and pulmonary embolism, and to protect against stroke in people who ha ...

).British National Formulary 57 March 2009 *

Methotrexate Methotrexate, formerly known as amethopterin, is a chemotherapy agent and immunosuppressive drug, immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancy, ectopic pregnancies. Types of cancers it is u ...

(

chemotherapy Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs (list of chemotherapeutic agents, chemotherapeutic agents or alkylating agents) in a standard chemotherapy re ...

and

immunosuppressant Immunosuppressive drugs, also known as immunosuppressive agents, immunosuppressants and antirejection medications, are drugs that inhibit or prevent the activity of the immune system. Classification Immunosuppressive drugs can be classified ...

). *

Typhoid Typhoid fever, also known simply as typhoid, is a disease caused by ''Salmonella enterica'' serotype Typhi bacteria, also called ''Salmonella'' Typhi. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often ther ...

Cholera Cholera () is an infection of the small intestine by some Strain (biology), strains of the Bacteria, bacterium ''Vibrio cholerae''. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea last ...

and BCG vaccines. *

Probenecid Probenecid, also sold under the brand name Probalan, is a medication that increases uric acid excretion in the urine. It is primarily used in treating gout and hyperuricemia. Probenecid was developed as an alternative to caronamide to competitive ...

reduces renal excretion and increases blood levels of amoxicillin. * Oral contraceptives potentially become less effective. *

Allopurinol Allopurinol is a medication used to decrease hyperuricemia, high blood uric acid levels. It is specifically used to prevent gout, prevent specific types of kidney stones and for the high uric acid levels that can occur with chemotherapy. It i ...

(

gout Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of pain in a red, tender, hot, and Joint effusion, swollen joint, caused by the deposition of needle-like crystals of uric acid known as monosodium urate crysta ...

treatment). *

Mycophenolate Mycophenolic acid is an immunosuppressant medication used to prevent rejection following organ transplantation and to treat autoimmune conditions such as Crohn's disease and lupus. Specifically it is used following kidney, heart, and liver t ...

(immunosuppressant) When given intravenously or intramuscularly: * It should not be mixed with blood products, or

proteinaceous Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...

fluids (including protein hydrolysates) or with intravenous lipid emulsions *

aminoglycoside Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar). The term can also refer ...

should be injected at a separate site from amoxicillin if the patient is prescribed both medications at the same time. Neither drug should be mixed in a syringe. Neither should they be mixed in an intravenous fluid container or giving set because of loss of activity of the aminoglycoside under these conditions. *

ciprofloxacin Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra-abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin ...

should not be mixed with amoxicillin. * Infusions containing

dextran Dextran is a complex branched glucan (polysaccharide derived from the condensation of glucose), originally derived from wine. IUPAC defines dextrans as "Branched poly-α-d-glucosides of microbial origin having glycosidic bonds predominantly C-1 ...

bicarbonate In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula . Bicarbonate serves a crucial bioche ...

should not be mixed with amoxicillin solutions.

Pharmacology

Amoxicillin (α-amino-''p''-hydroxybenzyl penicillin) is a semisynthetic derivative of penicillin with a structure similar to ampicillin but with better absorption when taken by mouth, thus yielding higher concentrations in blood and in urine. Amoxicillin diffuses easily into tissues and body fluids. It will cross the

placenta The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...

and is excreted into breastmilk in small quantities. It is metabolized by the liver and excreted into the urine. It has an onset of 30 minutes and a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 3.7 hours in newborns and 1.4 hours in adults. Amoxicillin attaches to the

cell wall A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

of susceptible bacteria and results in their death. It is effective against streptococci, pneumococci, enterococci, ''

Haemophilus influenzae ''Haemophilus influenzae'' (formerly called Pfeiffer's bacillus or ''Bacillus influenzae'') is a Gram-negative, Motility, non-motile, Coccobacillus, coccobacillary, facultative anaerobic organism, facultatively anaerobic, Capnophile, capnophili ...

'', ''Escherichia coli'', ''

Proteus mirabilis ''Proteus mirabilis'' is a Gram-negative, facultatively Anaerobic organism, anaerobic, rod-shaped bacterium. It shows swarming motility and urease activity. ''P. mirabilis'' causes 90% of all ''Proteus (bacterium), Proteus'' infections in human ...

'', ''

Neisseria meningitidis ''Neisseria meningitidis'', often referred to as the meningococcus, is a Gram-negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis. The bacterium is referred to a ...

'', ''

Neisseria gonorrhoeae ''Neisseria gonorrhoeae'', also known as ''gonococcus'' (singular) or ''gonococci'' (plural), is a species of Gram-negative diplococci bacteria first isolated by Albert Ludwig Sigesmund Neisser, Albert Neisser in 1879. An obligate human pathog ...

'', ''

Shigella ''Shigella'' is a genus of bacteria that is Gram negative, facultatively anaerobic, non–spore-forming, nonmotile, rod shaped, and is genetically nested within ''Escherichia''. The genus is named after Kiyoshi Shiga, who discovered it in 1 ...

'', ''

Chlamydia trachomatis ''Chlamydia trachomatis'' () is a Gram-negative, Anaerobic organism, anaerobic bacterium responsible for Chlamydia infection, chlamydia and trachoma. ''C. trachomatis'' exists in two forms, an extracellular infectious elementary body (EB) and an ...

'', ''Salmonella'', ''

Borrelia burgdorferi ''Borrelia burgdorferi'' is a bacterial species of the spirochete class in the genus '' Borrelia'', and is one of the causative agents of Lyme disease in humans. Along with a few similar genospecies, some of which also cause Lyme disease, it m ...

'', and ''Helicobacter pylori''. As a derivative of

, amoxicillin is a member of the

family and, like penicillins, is a β-lactam antibiotic. It inhibits

cross-link In chemistry and biology, a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural ...

age between the linear

peptidoglycan Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like layer (sacculus) that surrounds the bacterial cytoplasmic membrane. The sugar component consists of alternating ...

polymer chains that make up a major component of the bacterial

. It has two ionizable groups in the physiological range (the

amino group In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

in alpha-position to the

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula , where R, R', and R″ represent any group, typically organyl functional group, groups or hydrogen at ...

carbonyl group In organic chemistry, a carbonyl group is a functional group with the formula , composed of a carbon atom double-bonded to an oxygen atom, and it is divalent at the C atom. It is common to several classes of organic compounds (such as aldehydes ...

and the

carboxyl group In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl group (e.g. ...

Chemistry

Amoxicillin is a β-lactam and

in terms of

chemical structure A chemical structure of a molecule is a spatial arrangement of its atoms and their chemical bonds. Its determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target m ...

. It is structurally related to

. The experimental log P of amoxicillin is 0.87. It is described as an "ambiphilic"—between

hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...

and

lipophilic Lipophilicity (from Greek language, Greek λίπος "fat" and :wikt:φίλος, φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are c ...

—antibiotic.

History

Amoxicillin was one of several semisynthetic derivatives of 6-aminopenicillanic acid ( 6-APA) developed by the

Beecham Group The Beecham Group plc was a British pharmaceutical company. It was once a constituent of the FTSE 100 Index. Founded by Thomas Beecham who opened the first factory in St Helens, Lancashire in 1859, Beecham focused on marketing the business b ...

in the 1960s. It was invented by Anthony Alfred Walter Long and John Herbert Charles Nayler, two British scientists. It became available in 1972 and was the second

to reach the market (after

in 1961). Co-amoxiclav became available in 1981.

Society and culture

Economics

Amoxicillin is relatively inexpensive. In 2022, a survey of eight generic antibiotics commonly prescribed in the United States found their average cost to be about $42.67, while amoxicillin was sold for $12.14 on average.

Modes of delivery

Pharmaceutical manufacturers make amoxicillin in tri

hydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

form, for oral use available as capsules, regular, chewable and dispersible tablets, syrup and

pediatric Pediatrics (American English) also spelled paediatrics (British English), is the branch of medicine that involves the medical care of infants, children, adolescents, and young adults. In the United Kingdom, pediatrics covers many of their youth ...

suspension for oral use, and as the sodium salt for

intravenous Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutr ...

administration. An extended-release is available. The intravenous form of amoxicillin is not sold in the United States. When an intravenous aminopenicillin is required in the United States, ampicillin is typically used. When there is an adequate response to ampicillin, the course of antibiotic therapy may often be completed with oral amoxicillin. Research with mice indicated successful delivery using intraperitoneally injected amoxicillin-bearing microparticles.

Names

Amoxicillin is the international nonproprietary name (INN),

British Approved Name A British Approved Name (BAN) is the official, non-proprietary, or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia (BP). The BAN is also the official name used in some countries around the world, because ...

(BAN), and

United States Adopted Name A United States Adopted Name (USAN) is a unique nonproprietary name assigned to a medication marketed in the United States. Each name is assigned by the USAN Council, which is co-sponsored by the American Medical Association (AMA), the United St ...

(USAN), while amoxycillin is the Australian Approved Name (AAN). Amoxicillin is one of the semisynthetic penicillins discovered by the former pharmaceutical company

. The patent for amoxicillin has expired, thus amoxicillin and co-amoxiclav preparations are marketed under various brand names across the world.

Veterinary uses

Amoxicillin is also sometimes used as an antibiotic for animals. The use of amoxicillin for animals intended for human consumption (

chicken The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

, and

swine Suina (also known as Suiformes) is a suborder of omnivorous, non-ruminant artiodactyl mammals that includes the domestic pig and peccaries. A member of this clade is known as a suine. Suina includes the family Suidae, termed suids, known in ...

for example) has been approved.

Medical uses

Acute otitis media

Respiratory infections

''H. pylori''

Lyme borreliosis

Odontogenic infections

Skin infections

Infections in infants in resource-limited settings

Prevention of bacterial endocarditis

Combination treatment

Spectrum of activity

Adverse effects

Nonallergic rash

Interactions

Pharmacology

Chemistry

History

Society and culture

Economics

Modes of delivery

Names

Veterinary uses

References

Further reading