Thymol

• BPThymol
• Ph. Eur.Thymol
• USP–NFThymol

Thyme camphor; m-thymol; isopropyl-m-cresol; 2-isopropyl-5-methylphenol; thymolum

5-Methyl-2-(1-methylethyl)phenol · [89-83-8]

UNII 3J50XA376E · PubChem CID 6989

C10H14O · 150.22

Antimicrobial preservative, Flavouring agent

Typical concentrations: — · Dosage forms: Liquid

Used as an antimicrobial and flavouring agent in mouthwashes, gargles and toothpastes, and as a stabiliser (antioxidant) in halothane at about 0.01% w/w. It is also included in some topical antiseptic and antifungal preparations and in cosmetics and perfumes.

Colourless, often large crystals or a white crystalline powder with an aromatic, thyme-like odour and a pungent, burning taste. It is the main phenolic component of thyme oil.

Melting point

48–52 °C

Boiling point

about 232 °C

Solubility

very slightly soluble in water (about 1 in 1000); very soluble in ethanol (95%); freely soluble in ether, chloroform and fixed and volatile oils

Volatility

volatile at room temperature and readily steam-distilled

Stable but volatile, and may discolour on exposure to light and air. Store in a well-closed, light-resistant container in a cool place.

Forms liquid eutectic mixtures when triturated with camphor, menthol, phenol, phenyl salicylate and some other compounds. Incompatible with strong oxidising agents; as a phenol it may discolour with iron salts.

Obtained from thyme oil and other essential oils, or prepared synthetically, for example by alkylation of m-cresol with propene.

At the low levels used as an excipient it is generally well tolerated. Concentrated thymol irritates the skin and mucous membranes, may cause contact sensitisation, and is toxic if swallowed in large amounts.

Observe normal precautions for the quantity handled. Avoid skin and eye contact and inhalation of the vapour; gloves and eye protection are recommended.

Permitted in the USA as a synthetic flavouring substance in foods. Used in oral-care and topical products licensed in Europe and elsewhere.

Carvacrol; chlorocresol; cresol; menthol; phenol.

Thymol is often used together with menthol, eucalyptol and methyl salicylate in antiseptic mouthwashes. Its low water solubility means that an alcohol or a surfactant is usually needed in aqueous products.