I've developed a shellfish allergy over the last 4 or 5 years, which absolutely sucks because I LOVE shrimp, crab and lobster. Not oysters, so much. Now, however, a single shrimp will send me into hives, then waves of nausea. When it first happened I was at a party that had a dish of boiled shrimp on the buffet, and I had my fill. Thought i was gonna die that night, assumed it was just bad shrimp. A month later had a shrimp cocktail with dinner at my daughter's birthday dinner out, and the same thing happened, just not quite gonna-die bad.
I have a granddaughter who's allergic to peanuts. Her day care people have to keep stuff handy to treat her in case she gets someone's peanut butter sandwich, or a piece of some kid's Snickers bar. If you saw Hitch with Will Smith, that's what happens to her.
I have the respiratory allergies but not so bad as when I was younger. On certain days in the spring I had to wear a mask to school, like a doctor's mask, and I had a doctor's excuse from outdoor activities for recess and PE. Talk about enhancing your image with the other first graders! Even worse, the older kids!