Take care when cooking.
If everyone in the household isn't following an allergen-free diet, you want to be sure to avoid cross-contamination.
It's a good idea to have two sets of cooking and eating utensils — one exclusively for the allergic person — so that a knife used to cut a peanut butter sandwich isn't inadvertently used to butter the toast of someone who's allergic to peanuts.
All dishes and utensils should be thoroughly washed in hot, soapy water between uses.
Read more about preventing allergies.