Sun and heat allergies involve skin rashes that occur on exposure to sunlight and/or hot temperatures. True sun and heat allergies are rare. Sensitivity to sunlight (photosensitivity) or heat is much more common, and can be the result of using certain medications or topical skin products. Skin rashes caused by photosensitivity are known as photoallergic eruptions.

Sun and heat allergies cause skin reactions in the form of hives and rashes. Hives are red, raised and itchy areas of the skin that can appear singly or in batches. They can vary dramatically in size.

For people who suffer from allergies to the sun and heat, avoidance is the best treatment and prevention method. Staying out of the sunlight and avoiding heat as much as possible can effectively reduce allergic reactions. When venturing out into sunlight, it is essential to wear a hat and clothing that covers as much skin as possible. Sunscreen can be used to protect exposed skin. Loose and airy clothing will help to alleviate heat sensitivity.

Photoallergic eruptions may be avoided by staying out of the sun and heat when taking certain medications. A patient can also consult a physician for medications that may be better tolerated.

Moderate to severe hives may require medical attention. To make a diagnosis, a physician may take a patient’s complete medical history, perform blood and allergy tests to identify allergens and recommend medications such as antihistamines or corticosteroids to relieve symptoms. In rare circumstances, sun and heat allergies can cause the potentially life-threatening allergic reaction, anaphylactic shock, which requires emergency medical care.