Updated September 11, 2014.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Food allergies are becoming more common, with approximately 8% of children and 5% of adults suffering from at least one food allergy. It can be difficult for people to avoid their food allergen, and accidental exposure resulting in allergic reactions is common in people with food allergies. However, the U.S. Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA) required that food labeling include the eight most common food allergens present in packaged foods, including egg, milk, soy, wheat, peanut, tree nut, fish and shellfish.

While this legislation is helpful for people to identify foods with hidden food allergens, another potential danger exists: Vaccines with food proteins that could potentially trigger allergic reactions.

Pharmaceutical products contain excipients, which are inactive ingredients required for the manufacturing process and to help with the stability and function of medications. Many excipients are food products that could potentially cause allergic reactions in certain people with food allergies. As a result, many people with food allergies commonly avoid certain vaccines due to the fear of a hidden food allergen causing an allergic reaction. The following is a list of common food allergens and related vaccines containing relevant excipients:

EGG

There are four vaccines on the U.S. market that have some relationship to egg or chicken cells. The measles, mumps and rubella (MMR) and rabies vaccines are produced in chicken fibroblast cells and contain little to no egg protein. As a result, these vaccines pose no increased risk to people with egg allergy.

Influenza (flu) and yellow fever vaccines do contain egg protein, which has the potential to cause allergic reactions in people with egg allergy. For many years people with egg allergy were told not to receive the flu vaccine for fear of an allergic reaction. More recently, however, numerous studies on thousands of people with egg allergy show that the flu vaccine is very safe, even for people with life-threatening egg allergy. It is recommended, however, that people with egg allergy receive the flu vaccine in a physician’s office and be observed for 30 minutes afterwards. Some egg-free flu vaccines do exist, but they are currently approved only for adults. The yellow-fever vaccine, which is not a routine childhood vaccine, should be given only by an allergist (using a prick and progressive challenge technique) in people with egg allergy.

GELATIN

Many vaccines use gelatin as a stabilizer ingredient, and are well known causes of allergic reactions as a result of gelatin allergy. These vaccines include the MMR, varicella (chickenpox), flu, rabies, typhoid, yellow fever, zoster and Japanese encephalitis vaccines. People with gelatin allergy should have vaccine skin testing before receiving these vaccines.

MILK

Tetanus, diphtheria and acellular pertussis vaccines (Tdap and DTaP) contain casein, a milk protein. While the amount of casein present in these vaccines is very small, there have been a small number of milk-allergic people who have experienced allergic reactions as a result of receiving these vaccines. The association between allergic reactions from Tdap or DTaP and milk allergy is controversial.

For the most part, having a food allergy should not completely prevent a person from receiving a recommended vaccine. The benefits of a particular vaccine, especially routine childhood vaccines, far outweigh the risks. Allergists are uniquely skilled in the ability to administer a vaccine to a person with food allergies, by utilizing a prick and progressive challenge, as well as having the knowledge and equipment necessary to treat an allergic reaction that occurs as a result of receiving the vaccine.

Source:

Kelso JM. Potential Food Allergens in Medications. J Allergy Clin Immunol. 2014;133:1509-18.

DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.