Denatonium, usually available as denatonium benzoate (under

trade name A trade name, trading name, or business name is a pseudonym used by companies that do not operate under their registered company name. The term for this type of alternative name is fictitious business name. Registering the fictitious name with ...

s such as Denatrol, BITTERANT-b, BITTER+PLUS, Bitrex, Bitrix, and Aversion) and as denatonium saccharinate (BITTERANT-s), is the bitterest

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

known, with bitterness thresholds of 0.05 ppm for the benzoate and 0.01 ppm for the saccharinate. It was discovered in 1958 during research on

local anesthetic A local anesthetic (LA) is a medication that causes absence of all sensation (including pain) in a specific body part without loss of consciousness, providing local anesthesia, as opposed to a general anesthetic, which eliminates all sensati ...

s by T. & H. Smith of

Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...

, Scotland, and registered under the trademark Bitrex. Dilutions of as little as 10 ppm are unbearably bitter to most people. Denatonium salts are usually colorless and odorless solids, but are often traded as solutions. They are used as aversive agents (

bitterant A bitterant (or bittering agent) is a chemical that is added to a product to make it olfaction, smell or taste Taste#Bitterness, bitter. Bitterants are commonly used as aversive agents to discourage the inhalation or ingestion of toxic substances ...

s) to prevent inappropriate ingestion. Denatonium is used in

denatured alcohol Denatured alcohol, also known as methylated spirits, metho, or meths in Australia, Ireland, New Zealand, South Africa, and the United Kingdom, and as Rectified spirit, denatured rectified spirit, is ethanol that has additives to make it poisonou ...

antifreeze An antifreeze is an additive which lowers the freezing point of a water-based liquid. An antifreeze mixture is used to achieve freezing-point depression for cold environments. Common antifreezes also increase the boiling point of the liquid, allow ...

, preventive

nail biting Nail biting, also known as onychophagy or onychophagia, is an oral compulsive habit of biting one's fingernails. It is sometimes described as a parafunctional activity, the use of the mouth for an activity other than speaking, eating, or drink ...

preparations,

respirator A respirator is a device designed to protect the wearer from inhaling hazardous atmospheres including lead, lead fumes, vapors, gases and particulate matter such as dusts and airborne pathogens such as viruses. There are two main categories o ...

mask fit-testing, animal repellents, liquid soaps,

shampoo Shampoo () is a hair care product, typically in the form of a viscous liquid, that is formulated to be used for cleaning (scalp) hair. Less commonly, it is available in solid bar format. (" Dry shampoo" is a separate product.) Shampoo is use ...

s, and Nintendo Switch game cards to prevent accidental swallowing or choking by children. It is not known to pose any long-term health risks. The name ''denatonium'' reflects the substance's primary use as a denaturant and its chemical nature as a

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

, hence '' -onium'' as a

Neo-Latin Neo-LatinSidwell, Keith ''Classical Latin-Medieval Latin-Neo Latin'' in ; others, throughout. (also known as New Latin and Modern Latin) is the style of written Latin used in original literary, scholarly, and scientific works, first in Italy d ...

suffix In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns and adjectives, and verb endings, which form the conjugation of verbs. Suffixes can ca ...

Structure, synthesis, and physical properties

Denatonium is a

quaternary ammonium cation In organic chemistry, quaternary ammonium cations, also known as quats, are positively-charged polyatomic ions of the structure , where R is an alkyl group, an aryl group or organyl group. Unlike the ammonium ion () and the primary, secondary, ...

. It is composed as a

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

with any of several

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

s, such as

benzoate Benzoic acid () is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn," which ...

or saccharinate. It can be obtained by the quaternization of

lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...

, a popular anesthetic, with

benzyl chloride Benzyl chloride, or α-chlorotoluene, is an organic compound with the formula . This colorless liquid is a reactive organochlorine compound that is a widely used chemical building block. Preparation Benzyl chloride is prepared industrially ...

or a similar reagent. To obtain other salts, like the benzoate, the formed denatonium chloride is subjected to an anion exchange reaction with sodium benzoate, or first

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

to make denatonium hydroxide followed by neutralization with

benzoic acid Benzoic acid () is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn," which ...

. Other similar compounds are

procaine Procaine is a local anesthetic drug of the amino ester group. It is most commonly used in dental procedures to numb the area around a tooth and is also used to reduce the pain of intramuscular injection of penicillin. Owing to the ubiquity of ...

and

benzocaine Benzocaine, sold under the brand name Orajel amongst others, is a local anesthetic, belonging to the amino ester drug class, commonly used as a topical painkiller or in cough drops. It is the active ingredient in many over-the-counter ...

Biochemistry

Denatonium in humans is recognized by eight distinct bitter taste receptors: TAS2R4, TAS2R8, TAS2R10, TAS2R39, TAS2R43, TAS2R16, TAS2R46, and TAS2R47, being by far to the compound. Denatonium can act as a

bronchodilator A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lun ...

by activating bitter taste receptors in the airway smooth muscle.

Applications

The bitterness of the compound guides most applications of denatonium. Denatonium benzoate is used to denature ethanol so that it is not treated as an

alcoholic beverage Drinks containing alcohol (drug), alcohol are typically divided into three classes—beers, wines, and Distilled beverage, spirits—with alcohol content typically between 3% and 50%. Drinks with less than 0.5% are sometimes considered Non-al ...

with respect to taxation and sales restrictions. One designation in particular, SD-40B, indicates that ethanol has been denatured using denatonium benzoate. Denatonium is commonly included in placebos used in clinical trials to mimic the bitter taste of certain medications. Denatonium benzoate is an ingredient in certain

nail polish Nail polish (also known as nail varnish in British English or nail enamel) is a lacquer that can be applied to the human Nail (anatomy), fingernails or toenails to decorate and protect the nail plates. The formula has been revised repeatedly t ...

es and varnishes designed to discourage

, as the bitter denatonium serves as an

aversive In psychology, aversives are suffering, unpleasant Stimulus (physiology), stimuli that induce changes in behavior via negative reinforcement or positive punishment (psychology), punishment. By applying an aversive immediately before or after a be ...

. Denatonium also discourages consumption of poisonous

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

s such as

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...

and additives such as

ethylene glycol Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...

. It is also added to many kinds of harmful liquids, including

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

s (such as

nail polish remover Nail polish (also known as nail varnish in British English or nail enamel) is a lacquer that can be applied to the human Nail (anatomy), fingernails or toenails to decorate and protect the nail plates. The formula has been revised repeatedly t ...

paint Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...

varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmente ...

es, toiletries and other

personal care Personal care products are consumer products which are applied on various external parts of the body such as skin, hair, nails, lips, external genital and anal areas, as well as teeth and mucous membrane of the oral cavity, in order to make ...

items, special nail polish for preventing nail biting, and various other household products. It is also added to less hazardous aerosol products (such as gas dusters) to discourage

inhalant abuse Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication, in a manner not intended by the manufacturer. They ...

of the volatile vapors. In 1995, the U.S. state of

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

required that denatonium benzoate be added to products containing sweet-tasting ethylene glycol and methanol such as

and windshield washer fluid to prevent poisonings of children and animals. In December 2012, U.S. manufacturers voluntarily agreed to add denatonium benzoate to antifreeze sold nationwide. Animals are known to have different sensitivities to the effects of denatonium. It is used in some animal repellents (especially for such large

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s as

deer A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) ...

). It has been used to safeguard

rat poison Rodenticides are chemicals made and sold for the purpose of killing rodents. While commonly referred to as "rat poison", rodenticides are also used to kill mice, groundhog, woodchucks, chipmunks, porcupines, nutria, beavers, and voles. Some rod ...

s from human consumption, as humans are able to detect denatonium at much lower concentrations than rodents.

Nintendo Switch The is a video game console developed by Nintendo and released worldwide in most regions on March 3, 2017. Released in the middle of the Eighth generation of video game consoles, eighth generation of home consoles, the Switch succeeded the ...

and

Nintendo Switch 2 The is a hybrid video game console developed by Nintendo, released in most regions on June5, 2025. Like the original Nintendo Switch, Switch, it can be used as a Handheld game console, handheld, as a Tablet computer, tablet, or connected via ...

game cartridges are coated in denatonium benzoate to prevent young children from consuming them. Lithium button cells, which can cause severe internal injuries if swallowed, are sometimes coated with denatonium benzoate to discourage small children from swallowing them. Duracell 2025 packaging reverse side

References

{{reflist Benzoates Benzyl compounds Quaternary ammonium compounds Bitter compounds Safety *

Structure, synthesis, and physical properties

Biochemistry

Applications

See also

References