Hives Caused by Heat or Exercise (Cholinergic Urticaria)

hives (urticaria) on the abdomen after running
What is cholinergic urticaria and how is it treated?. Istockphoto.com/Stock Photo©Mr_Seng

Cholinergic urticaria (or heat urticaria) is a condition in which hives (urticaria) occur in response to a rise in body temperature from exercise, overheating, a fever, eating spicy foods, a hot bath or shower, or stress. It is a very common form of physical urticaria (hives caused by exposure to something physical in the environment.)

Symptoms and Appearance of Cholinergic Urticaria

Cholinergic urticaria manifests as multiple one- to three-millimeter (think: very tiny) red hives on the upper trunk and arms, although it can occur anywhere from the neck down to the thighs.

These hives are usually surrounded by a wide area of redness.

The hives of cholinergic urticaria usually develop within two to twenty minutes after the body temperature rises, although they can take up to an hour to present. They cause itching, tingling, burning, and warmth of the skin. The hives last for minutes to hours with an average of 30 minutes. The itching may be very intense.

Common Causes

It's believed that histamine released in response to stimulation by the parasympathetic nervous system is what triggers the hives of cholinergic urticaria. There are also indirect theories that explore the interaction of acetylcholine with mast cells, resulting in histamine release from the mast cells.

Who Is at Risk for This Condition?

Cholinergic urticaria tends to begin between late childhood and early adulthood. It is more common in people who have allergies and other forms of urticaria.

Other Forms of Physical Urticaria

Physical urticaria (hives caused by something physical in the environment) is responsible for up to 30 percent of cases of urticaria.

In addition to cholinergic urticaria, people may have physical urticaria in response to cold (cold urticaria), pressure (pressure urticaria), scratching (dermatographism), sunlight (solar urticaria), or even water (aquagenic urticaria).

Getting a Diagnosis

Cholinergic urticaria is diagnosed by history and reproducing the hives by replicating certain conditions.

Many times the patient is asked to exercise by jogging in place or riding a stationary bike and the time it takes for hives to develop is noted. There are no blood tests or scratch tests to diagnose cholinergic urticaria.

What Else Could It Be?

There are other conditions that may result in a rash or even hives in response to heat exposure. These may include:

  • Hot tub folliculitis: A bacterial infection that may occur hours to days after sitting in a hot tub, hot tub folliculitis is most commonly caused by the bacterium Pseudomonas aeruginosa. The rash is usually red, bumpy, and very itchy. The lesions may resemble acne, but hives up to three centimeters in diameter may also occur, making it somewhat difficult to distinguish from cholinergic urticaria. Many times it resolves on its own, but severe cases may require antibiotics.
  • Other causes of urticaria (non-physical causes): As noted above, physical urticaria such as cholinergic urticaria accounts for roughly one-third of urticaria. Other causes may be difficult to distinguish at first and include autoimmune conditions, allergies, parasitic infections, and more.

Treating Cholinergic Urticaria

One way to treat cholinergic urticaria is to prevent it from happening in the first place by limiting strenuous exercise.

That said, many people can not or do not want urticaria to limit their exercise routine in this way. While topical treatments such as hydrocortisone are not effective and can even be detrimental due to their side effects, there are other treatment options. These include: 

  • Medications: Since cholinergic urticaria occurs in response to the release of histamine by the body, H1 antihistamines such as Benadryl (diphenhydramine) and Chlor-Trimeton (chlorpheniramine) may be helpful. However, these can cause significant drowsiness. Less-sedating options are Claritin (loratadine) and Zyrtec (cetirizine). Another antihistamine Atarax or Vistaril (hydroxyzine) appears to be particularly effective but can cause drowsiness as well. Doxepin (a tricyclic antidepressant) may also be helpful when other treatments aren't working. This medication is not used for its role in depression, but rather for its actions on the histamine receptors in the body. Finally, terbutaline has been helpful for some people.
  • Physical approaches: Showering with hot water may cause a release of histamine throughout the body, depleting histamine stores and causing a 24-hour refractory period.

Cholinergic urticaria is usually fairly mild and self-limited, yet anaphylactic reactions have occurred. For severe urticaria, oral or intravenous steroids may be needed as well.

Coping With the Problem

Cholinergic urticaria can be a frustrating occurrence that often limits activities. What works well for one person may not for another, and preventing and treating the condition may require a fair amount of trial and error. That said, with time and patience, most people are able to control their symptoms so they can enjoy a hot (or at least tepid) shower and exercise.

Sources:

Kasper, Dennis L.., Anthony S. Fauci, and Stephen L.. Hauser. Harrison's Principles of Internal Medicine. New York: Mc Graw Hill Education, 2015. Print.

Koch, K., Weller, K., Werner, A., Maurer, M., and S. Altrichter. Antihistamine Updosing Reduces Disease Activity in Patients with Difficult-to-Treat Cholinergic Urticaria. Journal of Allergy and Clinical Immunology. 2016. 138(5):1483-1485.

Trevisonno, J., Balram, B., Netchiporouk, E., and M. Ben-Shoshan. Physical Urticaria: Review on Classification, Triggers, and Management with Special Focus on Prevalence Including a Meta-Analysis. Postgraduate Medicine. 2015. 117(6):565-70.

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