Exercise-induced urticaria (EIU) is a rare condition in which a person experiences hives triggered by exercise. It can make physical activity more difficult, but some tips can help you stay active.

Urticaria is the medical term for hives. These are itchy, inflamed, and discolored bumps that appear on the skin. Up to 1 in 5 people experience hives at least once in their lives.

Hives are a common symptom of allergies and intolerances, such as to certain foods, pollen, dander, and mold.

In rare cases, some people develop hives in response to physical activity. This is known as exercise-induced urticaria (EIU).

Although EIU usually isn’t serious, some people may develop exercise-induced anaphylaxis (EIA). Anaphylaxis is a life threatening allergic reaction that requires immediate treatment and emergency medical attention.

There’s no known cure for EIU, but taking medications called antihistamines may help reduce the immune reaction that causes hives.

Read on to learn more about EIU, including what causes it, how it’s treated, and how to manage it.

EIU can be classified into three types:

  • Cholinergic urticaria: Cholinergic urticaria are hives that form due to a rise in body temperature, such as during exercise or psychological stress.
  • Variant EIA: The variant form of EIU is similar to cholinergic urticaria, but symptoms only develop in response to exercise.
  • Classic EIA: The classic form is usually accompanied by classic symptoms of anaphylaxis, such as upper respiratory blockage and low blood pressure.

Hives are characterized by a rash on your skin that may:

  • appear as raised bumps or patches
  • appear on one part of your body or be widespread
  • feel itchy, sting, or burn
  • look pink or red on lighter skin tones
  • appear slightly lighter or darker than the surrounding skin on darker skin tones

The reaction tends to occur within about 30 minutes of starting exercise and lasts for around 2 hours, although this may vary from person to person.

The exact cause of EIU isn’t known.

Hives form when the immune system overreacts due to exposure to a specific trigger. This causes your body to produce antibodies called immunoglobulin E (IgE), which trigger the body’s inflammatory reaction and cause allergy symptoms.

In EIU, increased body temperature during exercise may trigger this immune response, leading to hives.

Allergies related to exercise may have a genetic component, but most people have no family history.

EIA seems to be more common in people assigned female at birth. Most cases have been reported in adolescents and young adults.

Is there a connection between food and exercise-induced urticaria?

Some people may have food-dependent EIU, where they only develop symptoms after they consume a certain food and exercise thereafter. Wheat is the most common food trigger, followed by shellfish.

Common locations for EIU seem to be the arms, neck, chest, and abdomen.

Case study

In a 2022 case study, researchers reported a 27-year-old male who first noticed EIU while playing soccer at the age of 8 years. The rash came back on his arms every practice and limited his ability to exercise.

When he was 22 years old, he noticed the rash developed within 20 minutes of running, and it would usually clear within 2 hours.

A healthcare professional can typically identify hives by looking at your skin. They will first perform a physical exam to look at your symptoms and ask you questions about:

  • your symptoms, including when you noticed them
  • your personal and family medical history
  • any underlying conditions you may have

To differentiate EIU from other forms of hives or skin conditions like eczema, heat rash, and contact dermatitis, they may order other tests. These include:

  • an exercise challenge test to see if exercise induces your hives
  • a skin prick test to check for specific allergies
  • blood tests
»Learn more:Allergy testing

There’s currently no cure for EIU, but some lifestyle changes and medications may help you prevent, manage, and treat allergy symptoms.

The most common treatment for EIU is moderation of exercise intensity and taking antihistamine medications. Antihistamines block a chemical released by your body during an allergic reaction called histamine.

Some people with EIU may still be able to exercise at low intensities, while others may need to avoid exercise entirely.

EIU most commonly occurs when your body temperature rises in response to exercise, so managing your body temperature is key. This can be very difficult during exercise, but some prevention tips may include:

  • taking antihistamines before exercise
  • doing light intensity exercise
  • swimming or trying other water-based activities
  • avoiding food for 4 to 6 hours before exercise, if you have food-dependent EIU

While hives themselves usually aren’t serious, they can be a symptom of a more severe allergic reaction. Some people develop anaphylaxis.

Anaphylaxis is a medical emergency. It’s important to seek immediate medical attention if you or somebody you’re with develops an anaphylactic reaction.

When to get immediate medical attention

Get immediate medical attention if you or someone you’re with experiences any of the following symptoms during or after exercise:

These may be symptoms of anaphylaxis, which is a medical emergency.

Most people experience hives once in a while. In general, these aren’t a cause for concern.

However, if you experience hives for no reason or quite frequently, especially after exercise, contact a healthcare professional. They can run tests to help you find the underlying cause.

You may find that your symptoms only appear after eating certain foods. Some research identified wheat as the most common trigger, followed by shellfish.

Chronic spontaneous urticaria is hives that develop for no apparent reason and last for a long time. They may be more common in people with vitamin D deficiency.

It’s a good idea to stop exercising if you develop hives, especially if you’ve previously had an anaphylaxis reaction. A doctor can help you decide if it’s safe for you to exercise and at what intensity.

EIU is a rare condition that causes hives to develop due to an allergic reaction to exercise.

Some people only develop an allergic reaction to exercise after eating a certain food, while others develop an allergic reaction every time they exercise.

There’s currently no cure for EIU, but taking antihistamines before exercising may help reduce your allergic reaction. You may also be able to continue exercising at a lower intensity if a doctor says it’s safe.