If you find yourself becoming blotchy or getting a runny nose after eating a bowl of oatmeal, you may be allergic or sensitive to a protein found in oats. This protein is called avenin.

Oat allergy and oat sensitivity both trigger an immune system response. This results in the formation of antibodies designed to combat an alien substance which the body perceives to be a threat, such as avenin.

Some people who find themselves experiencing symptoms after eating oats may not be allergic to oats at all, but rather, may have gluten sensitivity or celiac disease.

Gluten is a protein found in wheat. Oats do not contain gluten; however, they are often grown and processed in facilities that also handle wheat, rye, and other substances that do contain gluten.

Cross contamination between these products can result, causing trace amounts of gluten to contaminate oat products. If you must avoid gluten, make sure any product you eat or use that contains oats is labeled gluten free.

You may also experience gastric discomfort when eating oats if you are overly sensitive to high-fiber foods. Keeping a food diary may help you to determine if what you have is an allergy to avenin or a different condition.

Oat allergy is not common but can occur in infants, children, and adults. An allergy to oats might result in symptoms ranging from mild to severe, such as:

  • blotchy, irritated, itchy skin
  • rash or skin irritation on and in the mouth
  • scratchy throat
  • runny nose or nasal congestion
  • itchy eyes
  • nausea
  • vomiting
  • diarrhea
  • stomach pain
  • difficulty breathing
  • anaphylaxis

Oat sensitivity may result in milder symptoms that take longer to occur. These symptoms may, however, become chronic if you eat oats or come into contact with them repeatedly. These symptoms include:

  • stomach irritation and inflammation
  • diarrhea
  • fatigue

In infants and children, a reaction to oats can cause food protein–induced enterocolitis syndrome (FPIES). This condition affects the gastrointestinal tract. It can cause vomiting, dehydration, diarrhea, and poor growth.

If severe or long term, FPIES can also cause lethargy and starvation as well. Many foods, not just oats, can trigger FPIES.

Oat allergy can also adversely affect the skin when used topically. A 2007 study of children with atopic dermatitis found that a significant percentage of infants and children had allergic skin reactions to products containing oats, such as lotions.

Adults may also experience skin reactions if they are allergic or sensitive to oats and use products containing this ingredient.

If you are allergic or sensitive to avenin, avoiding oats in what you eat and the products you use is important. Check labels for words like oats, oat powder, and avenin. Things to avoid include:

  • oatmeal bath
  • oatmeal lotion
  • muesli
  • granola and granola bars
  • porridge
  • oatmeal
  • oatmeal cookies
  • beer
  • oatcake
  • oat milk
  • horse feed containing oat, such as oat hay

You can often stop mild allergic reactions to oats by taking an oral antihistamine. If you are having a skin reaction, topical corticosteroids may help.

There are several tests that can pinpoint food allergies of all kinds, including oats. These include:

  • Skin prick test (scratch test). This test can analyze your allergic reaction to many substances at once. Using a lancet, your doctor will place tiny amounts of allergens along with histamine and glycerin or saline under the skin of your forearm to see which ones generate a response. The test is not painful and takes around 20 to 40 minutes.
  • Patch test. This test uses patches treated with allergens. The patches remain in place on your back or arm for up to two days to determine if you have a delayed allergic reaction to oats.
  • Oral food challenge. This test requires you to ingest oats, in increasing amounts, to see if you have an allergic reaction. This test should only be done in a medical facility, where you can be treated for serious allergic symptoms, should they occur.

If you have a severe allergic reaction to oats, such as trouble breathing, or anaphylaxis, call 911, or see your doctor immediately.

As with any food allergy, these symptoms can quickly become life-threatening, but can usually be stopped with an epinephrine auto-injector sometimes called an EpiPen.

Even if you carry epinephrine and use it to stop an attack, call 911 or go to the nearest emergency room immediately following any episode of anaphylaxis.

Symptoms of anaphylaxis include:

  • drop in blood pressure
  • hives or itchy skin
  • wheezing or trouble breathing
  • swollen tongue or throat
  • nausea
  • vomiting
  • diarrhea
  • weak, rapid pulse
  • dizziness
  • fainting

Sensitivity or allergy to oats is uncommon. People with these conditions have an immune system reaction to avenin, a protein found in oats.

People who are sensitive to gluten, such as those with celiac disease, may also react adversely to oats due to cross-contamination of products.

An oat allergy can cause a potentially serious condition in infants and children. It can also cause atopic dermatitis.

If you suspect that you or your child has oat allergy or sensitivity, avoid oats and talk to your doctor.

If you are living with food allergies, check out the best allergy apps for helpful tips on dining out, recipes, and more.