Sun Allergy - Polymorphic Light Eruption
Polymorphic light eruption can be triggered by UVA as well as UVB in sunlight and is therefore difficult to prevent. UVA penetrates loose weave clothing, window glass and many sun blocks quite easily. Some patients find that they become naturally desensitised over the summer in the UK.
The skin reaction you develop is probably the one known as polymorphic light eruption or PLE. This is very common and usually begins with the first strong sun exposure of the year. In many individuals, continued sun exposure through the summer may result in the diminution of the problem.
Unfortunately, sunblock creams do not prevent sunlight from causing this condition. However, the other measures of clothing, hats and keeping out of the sun are the most important preventive measures. There is published evidence that dietary supplementation with particular unsaturated fatty acids, know as EPA, found in certain fish oils can protect against PLE. The official oil supplementation is taken for three months before the beginning of summer. The appropriate fish oils are sold as MaxEPA in Boots and may be obtained from Gold Shield health food suppliers.
Patients with this condition can sometimes be given ultraviolet light therapy in the late winter as this can help the skin to build up a natural protection. Access to this form of treatment would be through the local dermatology department.
Once the rash has developed, it is only likely to respond to treatment with potent topical steroids or even steroid tablets taken orally.
Clearly It is difficult to comment on the specifics but in general the commonest photosensitive eruption is polymorphic light eruption. This typically occurs when light levels increase in the spring or on holiday to sunnier climates.
I would suggest you are referred to a dermatologist for a diagnosis (a skin biopsy might help when the rash is up). Many patients with confirmed PLE can be desensitised effectively with PUVA which is available in most Dermatology Departments.
Updated 4/2009
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