Doctor K: Food allergies may appear unexpectedly

DEAR DOCTOR K: I recently ate shrimp and broke out in hives. This has never happened before. Could I have developed a new food allergy as an adult?

DEAR READER: Yes, you can, and it’s not that unusual. Allergic reactions are overblown immune responses against a harmless substance – in some cases, a food. Food allergies are most prevalent in childhood, but even if you escaped them then, you’re not necessarily off the hook. You can develop allergies at any point in your life, and fish and shellfish allergies are more likely than others to begin in adulthood.

What …

DEAR DOCTOR K: I recently ate shrimp and broke out in hives. This has never happened before. Could I have developed a new food allergy as an adult?

DEAR READER: Yes, you can, and it’s not that unusual. Allergic reactions are overblown immune responses against a harmless substance – in some cases, a food. Food allergies are most prevalent in childhood, but even if you escaped them then, you’re not necessarily off the hook. You can develop allergies at any point in your life, and fish and shellfish allergies are more likely than others to begin in adulthood.

What’s more, allergies that spring up in adulthood stay with you forever. In contrast, many children outgrow food allergies.

You want to be sure that your hives really did result from a food allergy, particularly if you love to eat shrimp. But please don’t try to prove that you have a shrimp allergy by eating more shrimp. (You may think I’m being funny, but I’ve had several patients do exactly that.) If your doctor hasn’t already done it, skin and blood tests can help establish that you do, in fact, have a shrimp allergy.

If you are allergic to shrimp, you’ll have to keep all traces of it out of your diet:

Shop cautiously. Food manufacturers must flag potential allergens in plain English. Still, read every label, even if you have purchased the item before. Manufacturers frequently change ingredients and may have slipped in an allergen.

Take care when cooking. If other people in your household continue to eat shrimp, you could get exposed to small amounts of shrimp proteins, and these could trigger an allergic reaction.

Dine out defensively. Let the chef know about your food allergy before you order.

Wear a medical ID bracelet.

Carry two doses of epinephrine. This medication, commonly known as an EpiPen or TwinJet, can be injected into your thigh should you feel an attack coming on.

To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.