I know it sucks having an allergy to food but in my opinion it's worse to have an intolerance (well unless you are deadly allergic then that is defiantly the worst). There is a difference between them even though some people don't know that. An allergy can make you itch, tongue/throat swell, red splotches appear on your skin, maybe upset you stomach a little, etc. An intolerance is your stomach feeling like someone is stabbing it repeatedly (at least in my experience).

Anyways, allergies from what I can tell can be taken care of with medicine, or in my grandmother's case (deadly allergic to fish and antidote) drinking lots and lots of water to flush it out of their system. Intolerances are a little harder to control since I don't tend to feel the affects until the next day, if I know I ate ham or took something with seafood in it I can drink lots of liquid and it helps a little.
If you are going to hold a pot luck or just a dinner party make sure to let people know if their is something high on the food allergen list like peanuts, fish or wheat. Know the ingredients in the food you make so when people ask you can answer and if you are absolutely not sure what to do ask your guests if they are allergic or intolerant to any food.