6 Easy-to-Miss Signs You Might Have a Food Allergy

Updated: Oct. 10, 2022

If you experience any of these strange symptoms, you may have a food allergy and your body could be reacting to something you've eaten.

Food allergies are on the rise

We think of food allergies as something that starts in childhood—and often, they do. According to the CDC, 13 percent of U.S. children, or one in eight, have a food allergy. Sometimes, kids can outgrow allergies to milk, eggs, soy, or wheat—but according to the American Academy of Family Physicians, people are less likely to outgrow allergies to peanuts, tree nuts, fish, or shellfish. Food allergies, though, can also develop any time throughout life.

“All people of all ages are susceptible to food allergy—babies to elderly,” says Stacey Galowitz, DO, an allergist/immunologist at ENT & Allergy Associates in Somerset, New Jersey. A 2019 study in JAMA Network Open led by Northwestern University Feinberg School of Medicine found that 10 percent of the 40,000 U.S. adults surveyed had food allergies, with nearly half having developed the allergy in adulthood.

Additional research has shown an upward trend in food allergies overall—and not just their diagnosis but an actual increase in cases. “According to the CDC the prevalence of food allergy in children has increased by 50 percent between 1997 and 2011,” says Vandana Sheth, RDN, a registered dietitian who specializes in food allergies and a spokesperson for the Academy of Nutrition and Dietetics. “The prevalence of peanut or tree nut allergy has more than tripled between 1997 and 2008.”

Why could this be? The American Academy of Allergy, Asthma, and Immunology notes a few potential reasons, include Western dietary changes and a lack of vitamin D. “Parents are avoiding and delaying the introduction of potentially allergenic foods to their children,” Sheth says, which is actually against the American Academy of Pediatrics’ updated guidelines for preventing peanut allergies. In addition, “researchers are noticing there may be a coincidence of food allergy prevalence with the availability of sunlight.”

But one of the strongest theories is a lack of exposure to germs. Why do we want to be exposed to things that could make us sick? “Due to being overly focused on cleanliness and overuse of antibiotics, children have limited exposure to wide range of bacteria,” Sheth says. These bugs train the body to tell the difference between things that can harm us and those that can’t; but an over-sensitive immune system can’t make those distinctions.

“With food allergies, one’s immune system overreacts to an ordinarily harmless food,” Dr. Galowitz says. The body then makes an antibody called immunoglobulin E (IgE), which is activated the next time you eat the food. This leads to a quick release of chemicals, including something called histamine, which create the symptoms of an allergic reaction.

“These antibodies can be activated with even the most minuscule amount of food—1/250th of a peanut is enough to trigger a reaction in some—so ‘just a taste’ is never safe for a person with food allergies,” Dr. Galowitz says. “The most common food allergens, responsible for up to 90 percent of all allergic reactions, are the proteins in cow’s milk, egg, soy, wheat, fish, shellfish, peanuts, and tree nuts.”

Any food can cause an allergy, though, such as all kinds of fruit, or sesame, which is of particular concern according to recent National Institutes of Health research linking it with other allergies in children.

So how can you know if you’re allergic? Some of these hard-to-read signs are more serious than others; but if any of them sound familiar to you after eating, it’s best to make an appointment to get tested. “A food allergy may sometimes exhibit with mild symptoms, but it must be taken seriously as it can progress rapidly,” Sheth says. “If you suspect a food allergy, it is important to get an evaluation, testing, and diagnosis by your allergist. It’s also important to work with a dietitian specializing in food allergies to guide you to ensure that you are meeting your nutritional needs adequately while staying safe.”

(Don’t miss what allergists have to say about at-home allergy tests.)

Here are some symptoms to watch for:

Food allergy symptom: Wheezing or coughing

Any time you have respiratory symptoms like non-stop wheezing or coughing after eating could be cause for concern, even if you don’t at first associate them with what you ate. These symptoms may be a sign of a life-threatening condition called anaphylaxis, which can make it hard to breathe. During the allergic reaction, certain molecules called leukotrienes are released that cause this constriction in your airway, Dr. Galowitz says.

“These can create respiratory symptoms that include coughing, wheezing, throat tightness or swelling, and chest tightness, similar to asthma symptoms,” she says. “There may also be swelling of the upper airway, causing stridor [wheezing].”

Children may describe the feeling as something stuck in their throat, Sheth says. A reaction like this can happen with any food you’re allergic to. “It’s always important to be prepared and have medication and an action plan in place if you have been diagnosed with a food allergy,” Sheth says.

If you have an epinephrine auto-injector (Epipen), use it and get help immediately. If you haven’t been diagnosed but are having symptoms that make it hard to breathe, also seek urgent medical treatment.

Food allergy symptom: Skin reactions

You might not immediately connect this symptom with food, but it’s not just touching things that can give you a strange rash—eating anything you’re allergic to can have this effect as well. “Histamine can cause the blood’s plasma to leak out of small blood vessels in the skin,” Dr. Galowitz says. “This can create symptoms such as hives, itching or redness of the skin, or swelling called angioedema. These symptoms can be mild or more diffuse.”

If the skin reaction seems not that bad and you have a known allergy, take an antihistamine like Benadryl and keep a close watch to make sure it doesn’t get worse. If the reaction spreads across different body parts, seek immediate help, Sheth says.

Food allergy symptom: Itchy mouth

If your mouth or tongue feels really swollen, it could be dangerous and require urgent care. But a bit of tingle or itchiness could be a milder reaction called an oral allergy—which is actually not really a food allergy at all.

Oral allergy syndrome, also known as pollen-food syndrome, is caused by cross-reacting allergens found in both pollen and raw fruits, vegetables, nuts, and herbs or spices,” Dr. Galowitz says. “It is essentially a case of mistaken identity: The immune system recognizes the pollen and similar proteins in the cross-reacting food and directs an allergic response to the food.”

Symptoms of oral allergy syndrome include itching of the mouth, throat and ears, and/or swelling of the lips, mouth, tongue, and throat—but, they’re usually short-lived. “The symptoms are usually confined to one area and do not normally progress beyond the mouth; because the symptoms usually subside quickly once the food is swallowed or removed from the mouth, treatment is not usually necessary,” Dr. Galowitz says.

Interestingly, people affected by oral allergy syndrome can usually eat the same fruits or vegetables in cooked form—for example, applesauce or apple juice—because the proteins are distorted during the heating process, so that the immune system no longer recognizes the food, she says.

“Although not everyone with a pollen allergy experiences oral allergy syndrome, about 55 percent of patients will,” Dr. Galowitz says.

midsection of woman with hands on stomachSiam Pukkato / EyeEm/Getty Images

Food allergy symptom: Gastrointestinal problems

Tummy troubles due to a food allergy can be tricky to isolate. It could be food poisoning, or a food intolerance—which is a problem digesting the food that doesn’t involve the immune system, and isn’t life-threatening.

Here’s how to tell the difference between food allergy and food intolerance. “Food intolerances are more common than food allergies, with over 30 percent of Americans believing they have an intolerance to one or more foods,” Dr. Galowitz says. A common example is a lactose intolerance from milk.

“Oftentimes, food intolerance responses take place in the digestive system where individuals are unable to properly break down a food,” Dr. Galowitz says. “Typically with a food intolerance, people can eat small amounts of the food without causing significant symptoms.” With a food allergy, “gastrointestinal symptoms of food allergies include vomiting, diarrhea, and abdominal cramping, which may be severe,” she says.

If you feel you’re having an extreme gastro reaction like this, especially along with other allergy symptoms, call your doctor.

Food allergy symptom: Sneezing or itchy eyes

You might think sneezing or itchy eyes are symptoms only of seasonal allergies to grass or pollen, but it could also be a reaction to a food. “As part of a food allergy, sneezing and itchy eyes can be signs of an allergic reaction due to the increase in secretions produced from histamine release,” Dr. Galowitz says.

This is different from your nose running after you eat something hot or spicy, which can trigger nasal nerves to become sensitive. Additionally, “some people also sneeze after eating a large meal when their stomach is full and becomes stretched—the cause is unknown but there may be a genetic component,” Dr. Galowitz says.

Food allergy-related sneezing is likely to be mild; but again, if it’s in conjunction with other serious systems, seek help.

Food allergy symptom: Dizziness

This is another sign you may need immediate care, as it could be heart-related—but we’re not talking about momentary dizziness from standing up from the table or the need for a quick post-meal snooze as blood rushes to your stomach for digestion. “Cardiac symptoms of a food allergy can include dizziness, pallor, a loss of consciousness, or a drop in blood pressure,” Dr. Galowitz says. This is termed anaphylactic shock, the most serious form of anaphylaxis.”These symptoms may occur alone, with no hives, or in combination with hives or angioedema [facial swelling],” she says.

It may be hard to tell if what you’re experiencing is this serious reaction. But follow your instincts as well: With severe allergic episodes like this, you might also just have a really bad feeling about it. “A symptom of a food allergic reaction may sometimes feel like there is a sense of doom or that something is not quite right,” Sheth says. “Children may sometimes describe symptoms as something bad is about to happen.”

And although many of these symptoms could also be something else, when it comes to food allergies it’s best to go with your gut and err on the side of caution. When in doubt, call your doctor. If the symptom goes away but you still suspect it may be food-related, make an appointment with an allergist for testing.