You eat one of your favorite foods, as usual.  You feel funny after 20 minutes. Not usual. One look in the mirror reveals that your lips are swollen beyond Angelina’s pretty proportions—definitely not usual.


As shocked as you might be, the truth is that “you could wake up tomorrow with an allergy to something you’ve eaten your whole life,” says Melinda M. Rathkopf, MD, of the Allergy, Asthma and Immunology Center of Alaska and assistant clinical professor at the University of  Washington.  Though FDA, adult onset food allergy occurs only in about 2 percent of the population, it is nonetheless on the rise.


The reasons for this are unclear, but experts have theories. One is that negative food reactions stem from an existing pollen allergy: Rathkopf says that if you’re allergic to pollens like ragweed or birch and you consume fruits or veggies with a protein similar to one found in pollen, your body may mistake the fresh produce for the environmental allergen. An allergic reaction then ensues, causing your mouth to itch and tingle.


Another theory is that the increase in adult food allergy is a byproduct of better hygiene. “Our current daily living includes many ways to keep us healthy from germs such as using plenty of antibiotics and being clean—as compared with farm or jungle living with exposure to many germs,” says Scott H. Secherer, MD, associate professor of pediatrics at the Jaffe Food Allergy Institute at Mount Sinai School of Medicine. “As such, our immune system keeps less busy fighting bad germs and more likely to get misdirected to attack harmless proteins in foods, animal danders, pollens, etc.”


Despite the fuzziness about its causes, what’s happening in the body during a reaction is no mystery.  “A food allergy occurs when an antibody, called immunoglobulin class E (IgE), or another immune cell, called a T-lymphocyte, encounters a food protein it recognizes and triggers an immunologic reaction,” says Matthew Jason Greenhawt, MD, a clinical lecturer at the University of Michigan School of Medicine.  In other words, your body mistakes certain food proteins for something harmful and your immune systems wages an attack.


Part of this attack is creating antibodies against the food, which means that the next time you eat the food, even a teeny amount, antibodies are on high alert to tell your immune system to respond. It’s this immune system response that leads to the symptoms of an allergic reaction.


How to Recognize an Allergy


Hives and annoyingly persistent itching are the most common, most visible, and most immediate adverse reactions to food. And they can last six to eight weeks—even with treatment. “It takes that long to shut down what’s going on internally that triggered the allergic reaction,” says dermatologist Audrey Kunin, MD.  Kunin’s treatment plan involves oral antihistamines, ranging from Benadryl to prescription options such as Atarax: “Particularly for women, I like the children’s syrup versions, which allow the patient to more readily monitor their dosage and balance it out with the resulting drowsiness. Sometimes I will also prescribe a topical cortisone cream.” Tepid baths also help. “ Oatmeal baths or baking soda baths can be very soothing,” says Kunin.


Other symptoms of a food allergy include stuffy nose, wheezing, cramping, vomiting, and/or a drop in blood pressure, says Rathkopf. Reactions can progress from mild to more severe with the most dangerous being anaphylaxis, where blood pressure drops dangerously low and the throat swells, making it difficult to breathe.


“It’s possible an individual will need prescribed medication like auto-injectable epinephrine in emergency situations,” Greenhawt says. “If such medication is prescribed, the person should always carry it.” Epinephrine is an adrenaline hormone your body produces naturally in response to stressful situations. The synthetic epinephrine you get as a medication has a similar effect on your body—increasing your heart rate and blood pressure, relaxing muscles in your airways, reducing swelling, and suppressing your immune system’s response to allergens.


But while auto-injectable epinephrine may relieve symptoms and prolong your life until you get medical attention, Greenhawt says it doesn’t substitute emergency care if a severe allergic reaction occurs. In fact, even if the epinephrine seems to have done its duty, you should still get to a hospital immediately; the drug’s effect will only last for 15 to 20 minutes and in a recent study up to 19 percent of users were shown to need a second dose. Some individuals may require further emergency care, but do not be afraid to use medicine: While it may temporarily increase your heart rate and blood pressure, the chances of it putting you at a greater risk for cardiac arrest are minimal.


Outgrowing an Allergy


You’ve probably heard people talk about getting over an allergy and “outgrowing” it.  While it is possible to lose an allergy as quickly and inexplicably as you developed it, this occurrence is most common in children, so don’t bank on saying good-bye to yours. Though there’s no clear explanation why, research shows it’s more likely that adult onset allergies will stick around as will certain types of allergies. “Typically, studies show that individuals allergic to milk, egg, wheat, and soy tend to outgrow these allergies by age six,” says Greenhawt. On the flipside, those allergic to nuts, fish, and shellfish are much less likely to lose their allergy—whether you’re 14 or 40.


When a Food “Allergy” Isn’t...


Experts say a lot more people believe that they have a food allergy than those who actually do. “About 25 percent of the population think they are allergic, but really only about 2 to 3 percent of people have a true immune response to food,” says Rathkopf, who adds that many mistake a food intolerance or sensitivity for an allergy.


Headache, psycho-behavioral changes (aversions based on taste, sight, smell, or past experience with a food), and fatigue are often tip-offs that the reaction may not represent an allergy. Additionally, “symptoms in an allergic reaction to a food usually develop within a few minutes to two hours after ingestion,” says Greenhawt. “Symptoms that occur more than a few hours after ingestion, with very rare exception, are unlikely to be related to a food allergy.”


Deconstructing Food Sensitivities


If you’re having a lot of stomach issues and ones that endure long after the 12-hour mark, your problem might be food intolerance or sensitivity—which means that while there’s no risk of your throat closing up, you might not feel so great the next day. Think of it as a guaranteed food hangover. Food intolerance doesn’t involve your immune system and can be caused by a variety of reasons.  Two common ones are the body’s lack of an enzyme to break down certain components of a food and sensitivity to specific additives in the food.”


Common nonallergic offenders are lactose (milk sugar) and gluten (protein found in wheat, barley, and rye). Symptoms of both lactose intolerance and gluten sensitivity usually involve gastrointestinal problems and discomfort, headaches, and fatigue.


Of the two sensitivities, however, gluten has the propensity to be the more serious.  Celiac disease is a digestive disorder that causes an immune reaction to the protein gluten, which damages the lining of the small intestine, diminishing the ability of the small intestine to absorb certain nutrients.  The symptoms of celiac can vary and tend to mimic those of other conditions such as chronic fatigue or iron-deficiency anemia, among others.


Life Without a Beloved Food


If you’re newly allergic or intolerant to something you’ve always enjoyed eating, you may be wondering if you’ll ever taste your “trigger” food again. The short answer: If you’re allergic, it’s highly unlikely. Although it’s possible you could be allergic to a food in its raw state and not when it’s heated since proteins are altered by heat, avoidance is still recommended.


You’ll also need to be diligent about what and where you eat outside your home.  Steer clear of restaurants with set menus or prix fixe situations, and call ahead to make sure they can accommodate your dietary needs.  Don’t be shy about calling to ask the kitchen about preparation methods and cross-contamination possibilities. You have to do it, and most places can be very accommodating about giving the necessary information.


When staying in for an at-home meal, double-check that the items on your grocery list are still okay for you to eat; manufacturers can change ingredients rapidly.  Under the FDA’s Food Allergen Labeling and Consumer Protection Act of 2004,  manufacturers are required to list major food allergens—milk, eggs, fish, crustacean shellfish, tree nuts, wheat, peanuts, and soybeans—on food packages.


There is some promising news:  Many studies, some of them funded by the Food Allergy Initiative, are ongoing to get foods back in your life and off your worry list.  It just may not be any time soon. “There’s a lot of research going on, from oral immunotherapy, which builds up tolerance orally—by incrementally increasing the food dosage—to reengineering the peanut,” Rathkopf says.