What Are Heat Hives?

Life in Louisiana can be hard on one’s skin. Our subtropical climate and love of the outdoors mean that many of us spend a lot of time out in the heat—both day and night. Heat hives are an especially common complaint in summer and fall at The Dermatology Clinic. We also often get questions about what causes hives and why certain people get them in reaction to the heat. To answer these questions, here’s a brief explanation of heat hives, and ways to alleviate recurring episodes of this annoying dermatitis.

What Are Heat Hives?

A diagram showing heat hives on an arm

Heat hives are essentially an allergic reaction to the heat. Physicians refer to the condition as cholinergic urticaria—a name that explains it quite perfectly. Cholinergic signals a relationship with acetylcholine, a neurotransmitter produced by the body that is responsible for the initial reaction. Urticaria is the Latin name for stinging nettle, a homeopathic herb that causes a contact skin irritation in humans.

What Causes Heat Hives?

The usual cause of cholinergic urticaria is exposure to heat, hence its common name. When the body’s surface temperature rises, it erroneously interprets heat as an allergen and responds by releasing acetylcholine into the skin’s nerve endings. This release prompts the body to secrete histamine. The allergic reaction usually manifests as prickly, itchy, or hot/burning skin. It also often produces a local rash or hives.

In addition to temperature, other allergens or triggers may cause or exacerbate episodes of heat hives, such as chocolate, stress, or insect bites like ants, chiggers, or mosquitos. Thus, for heat hives sufferers, the easiest prevention is staying cool and avoiding allergic triggers. Especially in Louisiana, however, it may impractical, or impossible, to always be in air-conditioned, mosquito-free environments or to completely circumvent the sun’s heat.

How Can You Treat Heat Hives?

A cold shower can bring quick, non-pharmaceutical relief from the symptoms of heat hives. A cool-down indoors or in the shade until the sensations pass may also suffice. When it doesn’t, an over-the-counter antihistamine or generic hydrocortisone cream is an effective treatment, depending on the severity and location of the outbreak. Regular sufferers may consider taking antihistamines prophylactically a couple weeks before the itchy seasons begin, or prior to visiting hot, sunny climates. Steroid creams may also be prescribed for more serious cases.

What Is the Difference Between Heat Hives vs. Prickly Heat?

Heat hives and prickly heat (miliaria rubra) are easily confused, as their triggers and symptoms are quite similar. Both occur when the skin gets hot. Prickly heat also manifests as a red-spotty rash, and the skin around the infection is usually red. However, miliaria rubra is not an allergy, rather a dermatological infection caused by a bacterium or by sweat gland blockages. Antihistamines work well for allergic reactions like heat hives, but generally do not help with prickly heat. It is important to have a medical professional diagnose any skin condition to determine the best treatment and safest way to prevent further discomfort.

If heat hives are impeding your enjoyment of the outdoors, schedule an appointment today at The Dermatology Clinic. Our team of physicians is well-versed in heat hives and other skin issues prevalent in the Pelican State. We’ll be happy to help identify the triggers, and suggest treatment and lifestyle strategies to cool down heat hives.

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