Another unexpected place you can find a food allergen is in vaccinations. Some vaccines are grown in eggs. That means that people that are allergic to eggs may have a reaction to these vaccines. My son was unable to get the MMR vaccine until recently when he got it under special conditions. For him to get the flu vaccine, they had to give him 6 different small shots over a couple of hours to avoid a reaction. The H1N1 shot was the worst for him.
Some lotions and soaps contain nuts to enhance the product. Play-doh has wheat in it, so those with a wheat allergy cannot touch play-doh.
There are many unexpected places that you can find food allergens. Caution is always best any time you are around someone with severe allergies.