Potential Allergens in Routinely Recommended Vaccines

Allergic reactions to vaccine are very rare. Ingredients within vaccines that can lead to potential allergic reactions are few and, in some cases of allergic reaction, it is unclear to which ingredient a person may have reacted.

The components on this table are vaccine ingredients that are suspected to have caused allergic reactions in medicinal products or vaccine recipients. Allergic reactions are immune mediated, either via IgE, or non-IgE dependent mechanisms, delayed type hypersensitivity or T cell mediated. Not all reactions are anaphylaxis, the most severe form of allergy.

Allergic reactions may occur at the site of inoculation (e.g. dermatitis) or be a delayed hypersensitivity leading to induration/nodule formation.

Most vaccines contain very small amounts of potential allergens, too small to induce serious allergic reactions even in people who have reacted to larger amounts of the component from other exposures. Also, Polysorbate 80, while not known to cause an allergy, can lead to a histamine release that may appear to be like an allergy. Increasingly, allergens have been removed from vaccines to the extent possible so individuals with a history of allergic reactions can safely get them, e.g. egg proteins in influenza vaccines.

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