What is it?
Thimerosal is used for the preservation of topical medications, cosmetics, vaccines, and contact lens solutions. Avoidance of thimerosal is accomplished by substituting products that contain an unrelated preservative. For eye preparations, benzalkonium chloride is a good substitute. Sterile saline contact lens solutions do not contain thimerosal. Skin antiseptics such as povidone-iodine (Betadine) or chlorhexidine gluconate (Hibiclens) may be substituted for Merthiolate. Sensitization to thimerosal is often caused by the mercury portion of the compound. When mercury is the sensitizer, cross-reactions can occur with other mercury containing compounds such as phenylmercuric nitrate or acetate. Substitution of phenol for thimerosal in vaccines avoids the rare severe reactions to thimerosal from vaccination.

How can I avoid it?
Avoidance requires reading the product labels, package inserts, Safety Data Sheets (SDS), and on occasion, direct communication with the manufacturer.

  • Preservative in pharmaceutical preparations
  • Cleansers (soap-free)
  • Cosmetics (make-up removers, eye moisturizers, eye shadows, mascaras, etc)
  • Eye preparations (contact lens solutions, eyedrops including prescription preparations)
  • Desensitization solutions
  • Liquid soap
  • Oral hygiene products
  • Pesticides
  • Skin testing solutions
  • Tattoo inks
  • Topical and systemic medicines (ear and nose drops, tincture of Merthiolate)
  • Topical and Intramuscular corticosteroids
  • Tuberculin tests
  • Vaccines
Other names for thimerosal:
  • [(o-carboxyphenyl)thio] Ethylmercury sodium salt
  • Ethyl (2-mercaptobenzoato-s) mercury sodium salt
  • Mercurochrome
  • Mercurothiolate
  • Merfamin
  • Merthiolate
  • Mertorgan
  • Merzonin
  • Sodium ethylmercurithiosalicylate
  • Sodium ethylmercurothiosalicylate
  • Sodium 2-(ethylmercurithio)benzoate
  • Sodium merthiolate
  • Thimersalate
  • Thiomersal
  • Thiomersalan
Potential cross-reacting/co-reacting substances:
  • Mercury derivatives
  • Thiosalicylic acid
  • Non-steroidal anti-inflammatory agents such as piroxicam (Feldene)

How safe is it?

Hang tight. We're thinking.