Thiomersal

Thiomersal (INN), or thimerosal (USAN, JAN), also sold under the name merthiolate, is an organomercury compound. It is a well-established antiseptic and antifungal agent.

It has been used as a preservative in vaccines, immunoglobulin preparations, skin test antigens, antivenins, ophthalmic and nasal products, and tattoo inks. Despite the scientific consensus that fears about its safety are unsubstantiated, its use as a vaccine preservative has been exploited by anti-vaccination groups.