Adverse reactions include headaches, nausea, and vomiting. While there are no officially recorded adverse reactions that can be traced specifically to the MSG component of vaccines, anyone who is sensitive to MSG in food should watch for reactions. MSG is present in the Varicella vaccine. Neomycin , an antibiotic, is added to vaccine cultures to prevent the growth of unwanted bacteria. Neomycin is present in the Varicella and MMR vaccines.
Egg proteins are present in miniscule amounts in vaccines which are prepared using chicken embryos.
While those with mild reactions to eggs are unlikely to react to their presence in vaccines, anyone with a history of anaphylactic response to egg or egg protein has a greater chance of adverse reactions. It is found in some formulations of Hib. Sulfite is also found in many foods and alcoholic beverages, and is often an irritant for people who suffer migraines. It can also cause diarrhea, vomiting, and severe cramps. Sulfites are present in some flu vaccines.