Oats contain a protein called avenin, which can cause an allergic reaction in some people. Symptoms of oat allergy can range from mild to moderate and affect the skin, gut, and airways.

A person who has eaten oats can sometimes feel unwell and experience the symptoms of an oat allergy. However, it could be that they have celiac disease, gluten intolerance, or a gluten allergy.

Celiac disease is an autoimmune response to gluten that affects 1 out of 100 people worldwide. The symptoms of gluten intolerance resemble those of celiac disease but are more like symptoms of a wheat allergy or intestinal condition such as irritable bowel syndrome (IBS).

Similarly, a gluten allergy can cause digestive issues after eating wheat. However, up to 65% of children with a wheat allergy find that it clears up by the time they reach adulthood. Additionally, people with a wheat allergy can still eat foods containing gluten, such as barley and rye, without any serious reactions.

Although oats do not contain gluten, processing oats alongside foods that contain gluten can lead to cross-contamination. This can result in a misdiagnosis.

This article looks at the symptoms of an oat allergy, as well as some diagnosis and treatment options.

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The symptoms of an oat allergy can vary from mild to moderate and affect the skin, gut, and airways.

Severe cases of food allergies can lead to anaphylactic shock, which can be life threatening if the person does not receive immediate treatment.

Symptoms of anaphylactic shock may include:

  • wheezing, which might resemble an asthma attack
  • a tight chest
  • a swollen tongue and throat, which restricts the airways
  • noisy breathing, especially when inhaling
  • a sudden decrease in blood pressure, which can result in shock
  • dizziness and confusion
  • collapse or loss of consciousness

The symptoms of anaphylactic shock typically appear within 1 hour of exposure. If a person has any signs or symptoms of anaphylactic shock, they should seek immediate medical attention.

Immediate allergic reaction

Symptoms of an oat allergy in adults, babies, and children include:

  • hives
  • a flushed face
  • an itchy rash around the tongue, mouth, or eyes, which can spread to other parts of the body
  • mild swelling of the lips, eyes, or face
  • an itchy throat and mouth
  • watery eyes
  • a runny or stuffy nose
  • sneezing
  • diarrhea
  • vomiting
  • bloating
  • stomach cramps

These symptoms indicate an immediate food allergy and can appear shortly after eating.

Most food allergy symptoms occur within 2 hours of consuming the allergen.

Delayed allergic reaction

Sometimes, there can be a delay in the symptoms of a food allergy, meaning that a reaction might not appear immediately after consuming the allergen.

In that case, reactions may be delayed by 4 to 6 hours, sometimes even longer.

Delayed signs and symptoms in babies and children can include:

  • eczema
  • reflux
  • stunted growth
  • constipation
  • diarrhea
  • swelling of the small bowel
  • significant stomach pain
  • frequent crying or distress

Food protein-induced enterocolitis syndrome (FPIES) is a delayed food allergy reaction. This produces severe gastrointestinal symptoms that tend to develop around 2 to 6 hours after consuming an allergen.

FPIES mostly affects infants who are consuming certain foods for the first time or while weaning.

Symptoms appear similar to those of a serious viral or bacterial infection. They include:

  • frequent vomiting
  • bloody diarrhea
  • dehydration as a result of vomiting and diarrhea

If a person has any of these symptoms, they need immediate medical help.

Treatment for FPIES includes intravenous rehydration.

There are multiple methods an allergist can use to diagnose an oat allergy. These include:

Tests

An allergist can test people for an oat allergy. They may use one of the following methods:

  • Skin prick test: An allergist will prick or inject the skin with a small amount of the diluted allergen, in this case, oats.
  • Blood test: If it is not possible to take a skin test, an allergist may take a blood test. These can be less sensitive in identifying allergies than skin tests.
  • Patch test: This can help identify delayed food allergies. An allergist will apply a small amount of the allergen to a patch. The person will wear the patch on their skin for 48 hours to check whether it causes a reaction.

Babies under 6 months will usually not have a skin prick test.

Elimination diet

An allergist may recommend an elimination diet for children.

This involves eliminating all oat-based foods and products from the diet for 2 to 4 weeks and monitoring the symptoms to see if they improve.

If the symptoms do improve, the person is likely allergic to oats.

Oral food challenge

Another way of testing for a food allergy is to take an oral food challenge. This requires a person to eat a small amount of oats under carefully monitored conditions.

An allergist will gradually increase the amount to check whether it causes any reaction. As soon as the oats cause any symptoms of an allergic reaction, the allergist will stop the test.

If the person has no reaction, the allergist will rule out oats as the cause. They may also give the person a placebo to make sure the results are accurate.

Anyone with an oat allergy should avoid consuming oats and oat-based products. To check for cross-contamination, people should check product labels for phrases including “might contain oats” or “manufactured in a facility that uses oat ingredients.”

An allergist may prescribe allergy medications, such as antihistamines, to help relieve any mild symptoms of an allergic reaction.

They may also prescribe an epinephrine auto-injector, which delivers adrenaline to the body. Manufacturers have designed epinephrine auto-injectors specifically for safe use in infants and toddlers.

If a person has a severe allergic reaction, they may need to use their epinephrine auto-injector. They will then need immediate medical attention.

If a person has any symptoms of a food allergy and suspects that they have an oat allergy, they can consult a doctor or an allergist.

A doctor or allergist can order tests to determine whether oats are the cause of the allergic reaction.

If a person experiences any severe symptoms, anaphylactic shock, or the symptoms of FPIES, they require immediate medical attention.

A person with an oat allergy may need to avoid certain products. These include certain foods and cosmetics such as those below.

Foods

People with an oat allergy will need to avoid any oat-based foods or drinks.

These may include:

  • oatmeal or porridge
  • oat milk
  • muesli
  • granola
  • flapjacks containing oat flour
  • oat cookies
  • any hot beverage containing oat milk
  • oat bread
  • oatcakes
  • oat bran

A person may also need to check the ingredients in cakes, muffins, and cookies, as some can contain oats.

Some beers can also contain oats, so a person should check the label or with the provider before consuming.

Cosmetics

Some moisturizers and creams contain oat proteins. Therefore, people with an oat allergy may need to avoid topical products containing oats, such as certain cosmetics or oatmeal baths.

One 2007 study found a high level of sensitivity to oats in infants who had atopic dermatitis and were using oat-based topical products.

However, a 2022 study found that personal care products containing oats can actually improve barrier function due to their anti-inflammatory, antioxidant, and antipruritic properties. People with a damaged skin barrier were more likely to have allergenic sensitization.

During a 3-year period, consumers of 445,820 products did not report any allergies.

People with an oat allergy can replace oats with other cereals and grains.

These can include:

  • sorghum
  • millet
  • corn
  • polenta
  • rice

There are many replacements for oat-based breakfast meals.

For example, people can make porridge out of millet instead, or they can soak chia seeds in milk or water to create a thick consistency as a replacement breakfast dish.

Some people have an allergy to the proteins in oats, which are called avenins. Symptoms of an oat allergy can range from mild to moderate.

If a person suspects that they have an oat allergy, they can consult an allergist, who can perform tests to reach a diagnosis. If the person does have an oat allergy, they will need to avoid any oat-based products.

If someone experiences a severe allergic reaction to oats, they need immediate medical attention.

If a person tests negative for an oat allergy but still reacts to oat-based products, they may have an intolerance or allergy to gluten. Eating oat products with the label “gluten-free” can ensure no cross-contamination from other products.