What are some chemical additives in vaccines?

Vaccines contain chemicals for three main reasons: to inactivate a virus or bacteria, to reduce spoilage, and to stabilize the vaccine so it won't lose its potency over time. The following are some of the substances added to vaccines:
  • Antibiotics prevent the growth of germs (bacteria). Neomycin is one of the more common antibiotics used for this purpose; penicillin is not used today.
  • Aluminum is an adjuvant -- a substance that helps another substance do its work. Aluminum helps the vaccine stimulate production of antibodies to fight off diseases. Adjuvants sometimes are added to vaccines to promote an earlier, a more potent, or a more persistent response to disease.
  • Formaldehyde kills unwanted viruses and bacteria and inactivates bacterial products.
  • Monosodium glutamate and 2-phenoxy-ethanol are stabilizers that keep the vaccine from changing in the presence of destabilizing forces such as heat, light, acidity, or humidity.
  • Thimerosal is a preservative that helps keep the vaccine from spoiling. Most patients do not have reactions to thimerosal in vaccines, even when patch or skin tests indicate that they are hypersensitive to the substance.
  • Egg protein is found in some vaccines that are prepared using embryonated chicken eggs. People who have had allergic responses to eggs or egg protein should not get these kinds of vaccines without consulting the doctor.

You can ask your healthcare provider or pharmacist for a copy of the vaccine package insert. If you are allergic to any of these substances, talk with your healthcare provider. However, the amount of chemical additives found in vaccines is very small and may not be enough to cause a serious allergic response.

Continue Learning about Vaccine

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.