When a person is exercising, he or she may develop hives, which are raised bumps on the skin that are more reddish in color on the outside edges than in the center. Hives may also occur as blisters, blotches, or red spots on any area of the body. In most cases, symptoms of hives are generally mild in nature, but occasionally hives do pose a life-threatening situation.

Sometimes, exercise can trigger an allergy in the body. The allergy occurs in the form of either small or large hives. The rash is usually reddish in color with generalized itching. The person may have difficulty breathing and experience cramps in the stomach. Swelling may occur in the hands, face, and tongue, often accompanied by a headache. Other serious symptoms include syncope (loss of consciousness), hypotension (low blood pressure), and even death. These symptoms are all possible indications of exercise-induced urticaria.

The following are the three primary types of exercise-induced urticaria:

• Cholinergic urticaria, also called generalized heat urticaria

• Classic-exercise-induced anaphylaxis

• Variant-exercise-induced anaphylaxis

Cholinergic urticaria is a physical allergy caused by sweating that manifests in the form of small papules that measure two to five millimeters and are usually surrounded by an erythematous halo, or a large wheel of redness. These lesions usually begin on the neck and upper chest, giving a flushed appearance, and then the rash spreads to the entire body, sometimes persisting for several hours. The lesions can be caused by the following conditions:

• Exercise

• Emotional stress

• Hot bath/showers

• Fever

• Eating spicy foods

• Cholinergic urticaria is the only form of hives that can be caused by emotional responses.

The second type of exercise-induced urticaria is classic exercise-induced anaphylaxis, or urticaria with upper respiratory hypotension, which occurs most commonly from exercises like running and jogging. It can also be incited by exercises like dancing, volleyball, skiing, and even normal yard work. Classic exercise-induced anaphylaxis is characterized by the following symptoms:

• Generalized itching

• Wheezing

• Nausea

• Headache

• Choking sensation

• Gastrointestinal colic

After the cessation of exercise, the symptoms can last from anywhere from 30 minutes to four hours. The frequencies of attacks tend to vary; episodes are not reproducible and therefore they are unpredictable. Instances tend to decrease with time, most likely because the patient learns how to avoid triggers.

The least common type of exercise-induced urticaria is variant exercise-induced anaphylaxis. Variant exercise-induced anaphylaxis is characterized by small hives and progresses to a classic anaphylactic reaction, a serious allergic response with symptoms that can include reduced blood pressure, breathing problems, swelling, dizziness, and loss of consciousness. This type only occurs in 10 percent of all cases of exercise-induced urticaria.

Red, itchy rashes appearing only after exercise suggest the presence of exercise-induced urticaria. To confirm, an exercise challenge test is conducted where the patient walks on a treadmill or rides an exercise bike while the doctor observes the patient’s symptoms. If the urticaria appears after exercising, then the test is positive for exercise-induced urticaria. It is important to note that a negative test result will not entirely rule out exercise-induced urticaria because the symptoms are variable. So, a negative result will require additional testing.

In another diagnostic test, the methacholine skin test, one hundred units of methacholine, or histamine, are diluted in saline water and injected into the skin. Methacholine narrows the airways and if hives appear, then it is confirmed that the patient is having exercise-induced anaphylaxis. Similarly, with this test a negative result does not rule out exercise-induced anaphylaxis because the symptoms are variable. A positive outcome with the methacholine skin test usually indicates a more serious form of exercise-induced anaphylaxis.

Most of the time, a patient with a history of symptoms after exercising is sufficient information for a doctor to make a diagnosis.

For some people, it may be necessary to modify or avoid certain types of exercise. Also, they should be mindful of certain foods that might contribute to an episode (it is best not to exercise for four to six hours after eating in general). The patient should also avoid taking medications like aspirin or non-steroidal anti-inflammatory drugs before exercise.

The patient should exercise with a partner, or someone aware of his or her condition, so the partner can administer epinephrine in the case of anaphylaxis or provide life-saving measures, in the rare instances that they are required. In the instance of an attack, try to remain calm; panic will only make the situation worse. The patient should stop exercising if they see or feel hives coming on to diminish the symptoms as quickly as possible.

A doctor commonly prescribes daily doses of antihistamines in an effort to treat the symptoms caused by exercise-induced anaphylaxis. Also, a cromolyn inhaler may be given as preventative treatment. However, the use of cromolyn, a cell stabilizer, has shown variable results in the treatment of patients with exercise-induced urticaria so further testing is still required.

Luckily, a person with exercise-induced urticaria is not required to stop exercising altogether. If they have experienced symptoms of exercise-induced urticaria in the past, modification to their exercise routine is not only smart but also necessary.

In most cases, exercise-induced urticaria disappears after some time. A severe anaphylactic reaction is a possibility so precautionary steps need to be taken to be able to continue to enjoy an active lifestyle.