SU and EPP are very misunderstood conditions and many patients express their anguish and discomfort, even anxiety when considering going outdoors. The most sensitive and difficult seasons for patients are seen to be spring and summer. The symptoms of SU (wheals – angiodema) are provoked primarily by UVA and UVB radiation, and sometimes parts of the visible spectrum of light (300-500 nanometers). Similarly, EPP patients we have observed in Europe and Australia experience most acute reactions to exposure at a ranges of 408-525 and 550-650 nanometers, this includes both UVA and visible light and explains why sunscreens cannot always offer relief from symptoms of either condition.

An intriguing trend, seen in anecdotal evidence from EPP patients, is that they are often able to detect when they should cease their exposure to the sun. There is an apparently common threshold, beyond which the patient knows they will become severely burnt, incurring blisters and lesions, particularly on their face and hands. Of course, at the point a patient becomes aware they are at risk their condition is not visible, sadly this makes it difficult for those around them to understand their distress and discomfort.

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