Product Allergen Watch: Triclosan

Lauren Campbell; Matthew J. Zirwas


Dermatitis. 2006;17(4):204-207. 

In This Article

Abstract and Introduction

Triclosan is a common antibacterial chemical currently in widespread use in household and health care-related products. Triclosan was first introduced in 1965 and has been marketed as cloxifenol, Irgasan CH 3565, and Irgasan DP 300. Its most common use is in antimicrobial hand soaps, but in the United States it can also be found in consumer products such as liquid dishwashing soaps, deodorants, and toothpastes. The concentrations used in products in the United States typically range from 0.15 to 0.3%. While allergy to triclosan-based products is uncommon, several cases of contact dermatitis secondary to triclosan have been reported.

Triclosan is a diphenyl ether (bis-phenyl) derivative known as 2,4,4'-trichloro-2'-hydroxydiphenyl ether or as 5-chloro-2-(2,4-dichlorophenoxy) phenol. Triclosan has good stability and is extremely lipophilic. It is a broad-spectrum biocide that has been used for many years in the United States as an antibacterial and antifungal agent.[1] It is currently used in the United States primarily in hand soaps although several deodorants, dish soaps, and toothpastes (eg, Colgate Total, Colgate-Palmolive Co., New York, NY) also contain triclosan. Typical concentrations in consumer products are between 0.15% and 0.3%.

For decades, triclosan was thought to work by attacking bacterial cell membranes. However, the primary mechanism of action was described in 1998 when McMurry and colleagues showed that triclosan works by blocking lipid synthesis in Escherichia coli by inhibiting the enzyme enoyl-acyl carrier protein reductase from type II bacterial fatty acid synthesis.[2,3,4] There may be additional mechanisms of action as well, as many biocides work via multiple mechanisms.


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