Itchy skin after sun exposure no rash

Topic Resources

Photosensitivity, sometimes referred to as a sun allergy, is an immune system reaction that is triggered by sunlight.

• Sunlight can trigger immune system reactions.

• People develop itchy eruptions or areas of redness and inflammation on patches of sun-exposed skin.

• The diagnosis is usually based on a doctor's evaluation.

• These reactions typically resolve without treatment.

In phototoxicity, people have pain and develop redness, inflammation, and sometimes brown or blue-gray discoloration in areas of skin that have been exposed to sunlight for a brief period. These symptoms resemble those of sunburn, but the reaction differs from sunburn in that it occurs only after the person has swallowed certain drugs (such as tetracyclines or diuretics) or chemical compounds or has applied them to the skin (such as perfume and coal tar). Some plants (including limes, celery, and parsley) contain compounds called furocoumarins that make some people's skin more sensitive to the effects of UV light. This reaction is called phytophotodermatitis. All phototoxic reactions appear only on areas of skin that have been exposed to the sun. They usually develop within hours after sun exposure.

In photoallergy, an allergic reaction causes redness, scaling, itching, and sometimes blisters and spots that resemble hives. This type of reaction can be caused by aftershave lotions, sunscreens, and sulfonamides. Substances that cause photoallergy are capable of doing so only after the person has been exposed to both the substance and sunlight (because sunlight is what makes the substance capable of triggering photoallergy). Photoallergic reactions can also affect areas of skin that have not been exposed to the sun. They usually develop 24 to 72 hours after sun exposure.

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, raised areas (called plaques) and, rarely, as blisters on sun-exposed skin. These plaques, which are itchy, typically appear 30 minutes to several hours after sun exposure. However, new patches may develop many hours or several days later.

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 (a process known as hardening).

• A doctor's evaluation

• Sometimes phototesting (skin patch and reaction reproduction test)

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 (phototesting) 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.

• Avoiding overexposure to sun, wear protective clothing, use sunscreens (prevention)

• For photosensitivity, stopping drugs or chemicals and sometimes taking corticosteroids

• For solar urticaria, antihistamines, corticosteroids, or sunscreens or sometimes ultraviolet (UV) light therapy

• For polymorphous light eruption, corticosteroids or hydroxychloroquine and sometimes UV light exposure

If possible, any drugs or chemicals that could cause photosensitivity should be discontinued after consulting with a doctor. To treat chemical photosensitivity reactions, corticosteroids are applied to the skin and the substance that is causing the reaction is avoided.

Solar urticaria can be difficult to treat, but doctors may try histamine (H1) blockers (antihistamines), corticosteroids applied to the skin, or sunscreens. If these treatments do not work, ultraviolet (UV) light therapy may be tried. Some people may be helped by omalizumab, which is a drug that may help decrease allergic responses in the body.

Taking Polypodium leucotomos (a dietary supplement made from certain tropical ferns) or nicotinamide (a form of vitamin B3) by mouth may be helpful in preventing symptoms in people susceptible to photosensitivity caused by sun exposure.

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