& Treatment of the Underlying Issue
Might Get You Back Outside
What is Photosensitivity?
Photosensitivity, sometimes referred to as a sun allergy, is an immune system reaction that is triggered by sunlight. Photosensitivity reactions are usually characterized by an itchy eruption on patches of sun-exposed skin. People may inherit a tendency to develop these reactions. Certain diseases also may cause more serious skin reactions to sunlight.
These reactions typically resolve without treatment, but seeing a dermatologist can help determine the triggers causing photosensitivity.
Types of Photosensitivity Disorders
Hives that develop after only a few minutes of exposure to sunlight are called solar urticaria. The hives typically last for minutes or hours. This disorder can be difficult to treat, but doctors may prescribe the following medication:
- Histamine (Hl) blockers
- Antimalarial drugs
- Ultraviolet (UV) light therapy
People with widely affected areas sometimes experience symptoms such as headaches and wheezing and feel dizzy, weak, and nauseated.
Over 100 substances, swallowed or applied to the skin, are known to cause sun-induced reactions on the skin. Treatment often involves applying corticosteroids to the skin and eliminating the substance that is causing the reaction. There are two types of chemical photosensitivity: photo toxicity and photo allergy.
People with a photo toxicity experience the following:
- Pain and redness
- Brown or blue-gray discoloration in areas of skin that have been exposed to sunlight for a brief period
- Reactions usually develop within hours after sun exposure
These symptoms typically occur after swallowing certain drugs or chemical compounds, or after applying them to the skin (such as perfume and coal tar). For those with phytophotodermatitis, some plants (including limes, celery, and parsley) make skin more sensitive to the effects of UV light.
People with a photo allergy experience the following:
- Allergic reaction causing redness
- Scaling, itching, and sometimes blisters and spots that resemble hives
A photo allergy will occur only after the person has been exposed to both the substance and sunlight and can affect areas of the skin not exposed to the sun. Symptoms usually develop 24 to 72 hours after sun exposure.
Polymorphous Light Eruption
This eruption is a reaction to sunlight (primarily UVA light) that is not fully understood. It is one of the most common sun-related skin problems and is most common among women and among people from northern climates who are not regularly exposed to the sun.
The eruption appears as multiple red bumps and irregular, red, plaques and, rarely, as blisters on the sun-exposed skin. The plaques typically appear 30 minutes to several hours after sun exposure, with new patches developing up to several days after. The eruption usually goes away within several days to weeks.
Typically, people with this condition who continue to go out in the sun gradually become less sensitive to the effects of sunlight.
There are no specific tests for photosensitivity reactions. A doctor suspects a photosensitivity reaction when a rash appears only in areas exposed to sunlight. A close review of the person’s medical history, skin symptoms, any diseases, drugs taken by mouth, or substances applied to the skin (such as drugs or cosmetics) may help a doctor pinpoint the cause of the photosensitivity reaction. Doctors may do tests to rule out diseases that are known to make some people susceptible to such reactions (such as systemic lupus erythematosus).
When a rash occurs on an area of skin that has been exposed to the sun and the diagnosis is not clear, doctors may do skin patch tests and reaction reproduction tests that involve exposure to UV light (photo testing) when the person is not using any drugs that cause photosensitivity reactions. These tests may help clarify which type of photosensitivity reaction may be the cause.
Is There a Treatment?
People with polymorphous light eruption or photosensitivity caused by systemic lupus erythematosus should be seen by a dermatologist to help treat symptoms. Treatment of the eruptions and flare -ups typically involve corticosteroids applied to the skin or hydroxychloroquine or corticosteroids taken by mouth. Occasionally, people with this problem can be desensitized to the effects of sunlight by gradually increasing their exposure to UV light.
How to Prevent Photosensitivity
All people should avoid excessive sun exposure, but people photosensitivity should be especially careful and do the following:
- Avoid sunlight as much as possible
- Use sunscreen regularly
- Wear protective clothes
- If possible, any drugs or chemicals that could cause photosensitivity should be discontinued after consulting with a doctor
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