GRAS listed. Included in the FDA Inactive Ingredients Guide (inhalation, liquid; oral, powder for solution). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.  R.C.罗，P.J.舍斯基，P.J.韦勒.药用辅料手册[M].北京：化学工业出版社，2005.
Thymol is a phenolic antiseptic, which has antibacterial and antifungal activity. However, it is not suitable for use as a preservative in pharmaceutical formulations because of its low aqueous solubility. The antimicrobial activity of thymol against eight oral bacteria has been studied in vitro. Inhibitory activity was noted against almost all organisms, and a synergistic effect was observed for combinations of thymol and eugenol and of thymol and carvacrol.The activity of thymol against bacteria commonly involved in upper respiratory tract infections has also been shown. Thymol is a more powerful disinfectant than phenol, but its low water solubility, its irritancy to tissues, and its inactivation by organic material, such as proteins, limit its use as a disinfectant. Thymol is chiefly used as a deodorant in antiseptic mouthwashes, gargles, and toothpastes, such as in Compound Thymol Glycerin BP, in which it has no antiseptic action. Thymol is also a true antioxidant and has been used at concentrations of 0.01% as an antioxidant for halothane, trichloroethylene, and tetrachloroethylene. More recently, thymol has been shown to enhance the in vitro percutaneous absorption of a number of drugs, including 5-fluorouracil, piroxicam, propranolol, naproxen, and tamoxifen. Studies have also demonstrated that the melting point of lidocaine is significantly lowered when it is mixed with thymol. The inhalation of thymol, in combination with other volatile substances, is used to alleviate the symptoms of colds, coughs, and associated respiratory disorders. Externally, thymol has been used in dusting powders for the treatment of fungal skin infections. Thymol was formerly used in the treatment of hookworm infections but has now been superseded by less toxic substances. In dentistry, thymol has been mixed with phenol and camphor to prepare cavities before filling, and mixed with zinc oxide to form a protective cap for dentine.Thymol has been included in food, perfume, and cosmetic products, and has also been used as a pesticide and fungicide.
Thymol is used in cosmetics, foods, and pharmaceutical applications as an excipient. However, thymol may be irritating when inhaled or following contact with the skin or eyes. It may also cause abdominal pain and vomiting, and sometimes stimulation followed by depression of the central nervous system following oral consumption. Respiratory arrest, attributed to acute nasal congestion and edema, has been reported in a 3-week-old patient due to the erroneous intranasal application of Karvol, a combination product that includes thymol. The patient recovered, but it was recommended that inhalation decongestants should not be used in children under the age of 5 years.(10) LD50 (guinea pig, oral): 0.88 g/kg(11) LD50 (mouse, IP): 0.11 g/kg LD50 (mouse, IV): 0.1 g/kg LD50 (mouse, oral): 0.64 g/kg LD50 (mouse, SC): 0.243 g/kg LD50 (rat, oral): 0.98 g/kg R.C.罗，P.J.舍斯基，P.J.韦勒.药用辅料手册[M].北京：化学工业出版社，2005.
Thymol is incompatible with iodine, alkalis, and oxidizing agents. It liquefies, or forms soft masses, on trituration with acetanilide, antipyrine, camphor, monobromated camphor, chloral hydrate, menthol, phenol, or quinine sulfate.  R.C.罗，P.J.舍斯基，P.J.韦勒.药用辅料手册[M].北京：化学工业出版社，2005.
Thymol is obtained from the volatile oil of thyme (Thymus vulgaris Linne (Fam Labiatae)) by fractional distillation followed by extraction and recrystallization. Thyme oil yields about 20–30% thymol. Thymol may also be produced synthetically from p-cymene, menthone, or piperitone, or by the interaction of m-cresol with isopropyl chloride.  R.C.罗，P.J.舍斯基，P.J.韦勒.药用辅料手册[M].北京：化学工业出版社，2005.