Thiomersal

Thiomersal is an organomercury compound that has been used since the 1930s as a preservative in various biological and pharmaceutical products, including vaccines, skin test antigens, and ophthalmic solutions (PubChem CID 7164). It functions as an effective antiseptic and antifungal agent by preventing the growth of microbes that could contaminate multi-dose vials (CDC, 2020). The compound metabolizes into ethylmercury and thiosalicylate; ethylmercury is cleared from the blood significantly faster than methylmercury, which minimizes the risk of toxic accumulation (WHO, 2012). Despite its long history of safe use, thiomersal has been the subject of public concern regarding potential neurodevelopmental links, though extensive scientific reviews by the CDC and FDA have found no evidence of harm at the doses used in vaccines (FDA, 2018). It remains a critical component for global health, ensuring vaccine stability in regions with limited refrigeration infrastructure (StatPearls, 2023).

Other names

ThimerosalMerthiolateSodium ethylmercurithiosalicylateEthyl(2-mercaptobenzoato-S)mercury sodium salt

Thiomersal acts by releasing ethylmercury, which binds to the sulfhydryl (thiol) groups of enzymes and proteins within microorganisms, thereby inhibiting their metabolic functions and leading to cell death (PubChem CID 7164).