Potential food allergens in medications

Excipients are all of the substances found in pharmaceuticals that are added to the active ingredient to provide a benefit in manufacturing, stability, bioavailability, or patient acceptability.  Some excipients are foods or substances derived from foods.  Food allergic patients may rarely have reactions to these products. In his review, John M. Kelso, MD details which food-derived substances are used as pharmaceutical excipients and in which medications. Furthermore, the safety of administration of these medications in food allergic patients is also discussed (J Allergy Clin Immunol 2014; 133(6): 1509-1518). 

Food allergens are proteins that can generate IgE-mediated responses in food-allergic individuals. Since some food-derived excipients in medications are proteins, there is potential for an allergic response.  However, in most cases there is not enough of the food protein present to cause a reaction even in an allergic individual.  For example, most influenza vaccines are grown in eggs,  however there are only trace amounts of the protein in the vaccines and they are considered safe in egg-allergic recipients.  Other vaccines, however, contain substantial quantities of gelatin and do pose a risk of an allergic reaction in those with gelatin allergy.  Other excipients are derived from foods but do not contain protein, thus fish-allergic patients need not avoid fish oil for example.  In some cases, a food-derived excipient such as lactose may be contaminated with milk protein accidentally.

Although food-derived excipients may contain food proteins, reactions are generally quite rare likely because protein amounts are too low to elicit a reaction. If there is a reaction to a medication, it may be from a specific lot that was accidentally contaminated with food protein. However, if a reaction occurs, allergy to the food component should be investigated as a possible cause.