Solar hives or solar urticaria is a rare condition that causes chronic hives when exposed to sunlight, both ultraviolet and visible light. Solar hives are classified as physical urticaria because it is triggered by an external stimulus, which is sunlight in this case.
When a person, who has solar allergy, is exposed to sunlight, within minutes a reaction occurs causing red itchy bumps on the skin. Usually these hives last for not more than 24 hrs. Usually hives develop on the face and hands as these are the most exposed body parts. In some cases, itching is accompanied with a burning sensation causing discomfort to the person with solar hives.
The cause for the occurrence of solar hives due to an agent called photo allergen. The human body when exposed to light generates photo allergen in the skin and the immune sometimes reacts against this agent resulting in a histamine release. The release of histamine on the skin causes solar hives.
Symptoms of Solar Hives
- When exposed to sunlight, appearance of skin rashes in exposed areas of skin.
- Redness of skin is accompanied by itchiness and swelling.
- In some cases, there is burning sensation without pain.
- When hives affect large areas on skin, some people have headaches, nausea and weakness.
- Usually hives disappear on cessation of exposure to sunlight. Symptoms do not last for more than 24 hrs.
Diagnosis of solar hives:
Solar urticaria is difficult to diagnose, but its presence can be confirmed by a phototest. In this test, the patient is exposed to various wavelengths of light to determine the exact wavelength that brings about the solar allergic reaction.
Preventive Measures for Avoiding Solar Hives
The best way to prevent occurrence of solar hives is to avoid the sun or even indoor lights.
While outdoors, wear protective clothing, sunscreens, and ensure you cover your body parts. Consider installing UV protective shields over glass windows.
Alter your lifestyle in order to minimize the time spent outdoors during the day light. For example, you can change working hours to night shifts and succumb to indoor recreational activities.
Using a self- tanning lotion that contains dihydroxyacetone can be useful to prevent solar hives occurrence, especially in people who have visible induced solar hives.
Most people suffering with solar urticaria are allergic to UVA light, and some are allergic to both UVA and UVB light. But most sunscreens provide protection against UVB light and provide sunburn protection. So ensure you select a sunscreen which has a UVA sunscreen rating that is measured with ppd rating. ppd rating measures tanning or pigment darkening.
People who suffer with solar urticaria or solar hives may find it difficult to move on with normal day-to-day activities. By following the above mentioned preventive measures, you can avoid the occurrence of solar hives.