About 8% of children and 10% of adults in the United States have food allergies. Itching is the most common symptom of an allergic reaction to food. It can begin within a few minutes or a few hours of eating even a tiny amount of the allergy-causing food. The itchiness may be in your mouth or on your skin, often in the form of a rash such as hives or eczema. You might also have swelling.
More than 170 foods are known to cause allergic reactions, and if you’re allergic to one food, you’re more likely to be allergic to other foods. The most common way to treat food allergies is to avoid the allergy-causing food and consider seeing an allergist for allergy testing.
Below are some of the most common foods that cause itchy skin and other allergy symptoms.
Milk. A milk allergy is one of the most common food allergies in children, who can be allergic to breastmilk, cow’s milk, or milk from other mammals like goats, buffalo, and sheep. Symptoms of a milk allergy include hives, wheezing, and digestive problems. Symptoms that may take longer to develop include loose stools, abdominal cramps, and colic in babies. Many kids outgrow milk allergies, but not all children do.
Milk allergies are different from lactose intolerance, though both can cause digestive problems. A milk allergy triggers an immune system response, and milk intolerance does not. Also, lactose intolerance requires different treatment.
Eggs. An egg allergy is also one of the most common types of food allergies in children, and 70% of kids will outgrow it. An egg allergy occurs when the body’s immune system reacts to the proteins found in egg yolks and egg whites. Symptoms include hives, indigestion, wheezing, swelling, and shortness of breath. Some people with eczema find that eating eggs aggravates the itchy skin condition. If you’re allergic to chicken eggs, you may also be allergic to other types of eggs, such as goose, duck, turkey, or quail.
Fish. Unlike milk and eggs, a fish allergy is one that may develop in adulthood. Up to 40% of people who report having a fish allergy said it was not an issue until they were adults. An allergy to finned fish, such as tuna or salmon, is different from an allergy to shellfish, such as lobster (more on that next). Symptoms include skin rash, nausea, diarrhea, headaches, and stuffy nose.
Shellfish. A shellfish allergy is triggered by foods like shrimp, crab, lobster, squid, oysters, and scallops. Some people are allergic to all types of shellfish, and other people are allergic to certain types. Symptoms are similar to fish allergy symptoms, such as hives, swelling of the face, wheezing, and nausea.
Wheat. Wheat is a common ingredient in bread, but it’s also in food you may not expect, such as hot dogs and soy sauce. A wheat allergy is different from a gluten allergy. A wheat allergy happens when your body reacts to the proteins found in wheat, which are albumin, globulin, gliadin, and gluten. With celiac disease, the gluten protein in particular causes an abnormal immune system reaction.
Soy, Soy, a legume that’s often used in baby formula and processed foods, is a common food allergen in children under age 3. Like milk and egg allergies, many kids outgrow this allergy by adulthood. Symptoms include itchy skin, especially on the face and mouth.
Peanuts. Peanut allergies are the most common cause of food-related anaphylaxis, a life-threatening reaction that requires emergency medical treatment. Besides from eating peanuts, reactions can also happen from cross-contamination from other food and inhaling peanut dust or peanut oil spray. Symptoms are similar to other food allergy symptoms: itching, hives, swelling, digestive problems, runny nose, and trouble breathing.
Tree nuts. Like peanuts, tree nuts are another common cause of anaphylaxis from food. There are many tree nuts, including cashews, almonds, walnuts, and pine nuts. An allergic reaction may come from the nut itself or nut-based oils, butter, flours, or milks. Between 25% and 40% of people who have a peanut allergy also are allergic to at least one type of tree nut.
Sesame. Sesame allergies are ninth most common cause of food allergies. Most people who are allergic to sesame will have other food allergies. Symptoms range from mild skin rash to anaphylaxis.
Sesame is used as a seed, oil, or paste in many products including food, medicines, cosmetics, and pet food. But sesame does not have to be listed on food products as an allergen. Read food labels and ingredient lists closely to look for sesame.
What You Can Do
If you think you have a food allergy, stop eating it and make an appointment with your doctor or an allergist. They will ask about your symptoms and family history with allergies, and they may give you a physical exam.
Your doctor may recommend a skin prick test, where skin on your arm or back is pricked with a tiny amount of various allergy triggers. If your skin gets red, swollen, or itchy, then you are allergic to the food or substance. Your doctor also may order a blood test, where your blood is drawn and tested in a lab with different foods. They also measure the amount of an allergy-related antibody called immunoglobulin E (IgE).
Your doctor may suggest that you not eat the suspected food for a few weeks, and then slowly add the food back to see how you feel. This is called an elimination diet. But elimination diets cannot tell the difference between a food allergy and a food sensitivity. And they are not recommended for people who had a serious reaction to the food in the past.
The only way to completely avoid an allergic reaction is to not eat the allergy-causing food. But accidents happen. If you have a mild allergic reaction, an over-the-counter antihistamine can help soothe minor symptoms. Serious reactions may require an injection of epinephrine, whether at a hospital or from an autoinjector such as an EpiPen.