Published by PMR of NY & CT
You may have eaten shrimp for decades without a second thought. Then one evening your lips swell and hives spread across your chest. It can feel baffling, but it happens. An adult onset food allergy is one that appears for the first time after childhood, sometimes to a food you have always eaten.
Food allergies in adults are more common than many people realize, and reactions can be just as serious as they are in children. A clear diagnosis from an allergist and a simple emergency plan can help you get back to eating out, traveling and staying active with confidence.
Why adult onset food allergy happens
A food allergy happens when your immune system mistakes a food protein for a threat. It makes allergy antibodies, called IgE, against that protein. The next time you eat the food, those antibodies trigger the release of histamine and other chemicals that cause symptoms.
Researchers don't fully understand why this can switch on later in life. Changes in the immune system, new exposures and other allergic conditions, such as hay fever, may all play a part. In general, an adult onset food allergy tends to stick around. It is less likely to fade than some allergies that start in childhood.
Common triggers in adults
Any food can cause an allergy, but these are among the most common in adults:
- Shellfish, such as shrimp, crab and lobster. Shellfish allergy is the most common food allergy in U.S. adults and often starts in adulthood.
- Fin fish, such as salmon, tuna and cod
- Peanuts and tree nuts
Two other patterns are worth knowing about:
- Pollen-food allergy syndrome, also called oral allergy syndrome. People with hay fever may notice itching or tingling in the mouth after eating certain raw fruits, vegetables or nuts, because their proteins resemble pollen. Symptoms are usually mild and limited to the mouth.
- Alpha-gal syndrome. A bite from certain ticks, mainly the lone star tick in the U.S., can lead to an allergy to red meat such as beef, pork and lamb. Reactions often start several hours after a meal, which makes the link easy to miss. Lone star ticks are found in parts of the Northeast, including New York.
How an allergist makes the diagnosis
If you suspect a new food allergy, see a board-certified allergist rather than cutting foods out on your own. Your allergist will ask what you ate, how much, how quickly symptoms began and what they looked like.
Testing may include skin prick tests, in which a tiny amount of food extract is pricked into the surface of your skin to see whether a raised bump forms, and blood tests that measure IgE to specific foods. A positive test alone doesn't prove an allergy, so your allergist reads the results alongside your history. If the picture is still unclear, they may suggest a supervised feeding test in the office. Home test kits are no substitute for this process.
Everyday life with a food allergy
Once you know your trigger, a few habits help keep you safe:
- Carry your epinephrine auto-injector or nasal spray everywhere if one is prescribed. Many allergists advise keeping two doses with you.
- Tell your server about your allergy each time you order, and ask how dishes are made. Shared fryers, grills and utensils can transfer allergens.
- Wear a medical ID, and show the people you live and work with how to use your epinephrine.
- Mention your allergy to every health care provider. Some massage oils and lotions are made from nut or seed oils, for example, so let your medical massage therapist know before a session.
Anaphylaxis: what to do in an emergency
Anaphylaxis is a severe allergic reaction that can become life-threatening within minutes. Adults sometimes wave off early signs or try to drive themselves to the hospital. Neither is safe.
If you have trouble breathing, a tight throat, a swollen tongue or feel faint after eating, or a reaction involves more than one part of your body, use your epinephrine right away and call 911. An antihistamine can ease itching, but it can't stop anaphylaxis, so never take one in place of epinephrine. After a severe reaction, go to the emergency room even if you feel better, because symptoms can return.
Frequently asked questions
Can adults outgrow a food allergy?
Sometimes, but it is much less common than in children. Many children outgrow milk and egg allergies, while allergies to shellfish, fish, peanuts and tree nuts usually last. An allergy that first appears in adulthood is likely to persist. Your allergist may retest you over time, but never eat a food that caused a reaction just to see whether you've outgrown it.
Is it safe to exercise if you have a food allergy?
For most people, yes. A small number of people have food-dependent, exercise-induced anaphylaxis, in which a food causes a reaction only when they exercise within a few hours of eating it. If you've had allergy symptoms during a workout, tell your allergist. You may need to time meals around exercise, carry epinephrine when you train and work out with a partner.
Do I need epinephrine if my reactions have been mild?
Possibly. A mild reaction in the past doesn't mean the next one will be mild, so allergists often prescribe epinephrine to adults with a confirmed food allergy, especially to peanuts, tree nuts, fish or shellfish. Asthma also raises the risk of a severe reaction. Ask your allergist for a written emergency action plan that spells out when to use it and when to call 911.
Keep moving with help from PMR
A food allergy shouldn't stop you from staying active. If pain or an injury is limiting your workouts or daily routine, Physical Medicine & Rehabilitation of NY & CT (PMR) offers sports medicine and performance care close to home. For allergy testing and treatment, see a board-certified allergist. Request an appointment online, and we’ll contact you to pick a day and time.
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