Sun Sensitivity (Polymorphic Light Eruption)
The skin reaction you develop in the sun is probably polymorphic light eruption (PLE). This is very common and usually begins with the first strong sun exposure in the spring or with the increased light levels of a sunny holiday. In many individuals, the problem gets better through the summer as the skin gets used to the higher light levels.
Polymorphic light eruption can be triggered by UVA as well as UVB in sunlight and can develop indoors and if wearing loose weave clothing as UVA can pass through.
Measures to reduce sun exposure help to prevent the condition. Close weave clothing, hats and keeping out of the sun are particularly important preventive measures. Sunblock creams may help, but it is important to use a high Sun Protection Factor (SPF) cream, at least SPF30, which has both UVA and UVB protection. There is some evidence that dietary supplements containing an extract of a tropical fern (Polypodium leucotomos) may help to reduce the risk of the rash developing.
If the rash develops, the use of a topical steroid cream can help to settle the inflammation in the skin and an oral antihistamine to control the itch. If you are badly affected, your doctor may give you a short course of steroid tablets and this can sometimes be useful to have on holiday to take in the event of an outbreak.
Some people manage to prevent the problem by gradually increasing their sun exposure to harden the skin. Patients who are severely affected with this condition can sometimes be given ultraviolet light therapy in the early spring as this can help the skin to build up a natural protection. You would need to go to your local hospital dermatology department to obtain this treatment.
If the diagnosis is uncertain, then it may help to see a dermatologist (a skin biopsy might help to exclude other sun induced rashes when the rash is present and patch testing to exclude an allergy to sun screen ingredients).