What Parents Should Know About Thimerosal
Answers from the AAP to frequently asked questions about thimerosal used in vaccines.

Thimerosal Preservative and Routinely Recommended Childhood Vaccines
Thimerosal is a preservative that contains a form of mercury (ethylmercury). Thimerosal was used in very small amounts for over 50 years as a preservative in some vaccines and to protect multi-dose vials of vaccines from bacterial contamination. Some parents, researchers and others have expressed concerns about a potential link between health problems, particularly autism, and vaccines containing thimerosal. There is no convincing evidence of harm caused by the small amounts of thimerosal in vaccines, except for minor effects like swelling and redness at the injection site due to sensitivity to thimerosal.

Additional Resources on Thimerosal

• Centers for Disease Control and Prevention: Mercury and Vaccines (Thimerosal)
• Immunization Action Coalition: Thimerosal Resources
• Study Fails to Show A Connection Between Thimerosal and Autism
• National Network for Immunization Information