WATER PILLS AND SUNLIGHT
Certain drugs have the ability to induce an allergic hypersensitivity to sunlight, a side effect known as phototoxicity. Perhaps the most common medicines to do this are the thiazide diuretics (“water pills”) that so many people rely upon for the control of high blood pressure or heart failure.
Phototoxic effects in the skin include itching and a red, bumpy rash (due to many small blisters) on parts of the body exposed to sunlight. When the drug is stopped right away, the rash may quickly disappear, even if it continues to be exposed to the sun. However, if the drug is ever given again, the rash quickly returns and will continue to cause discomfort for the rest of the person’s life whenever he or she is exposed to sunlight.
In such cases, it may be possible to shield the skin with PUVA (an artificial deep suntan). To do this, the Archives of Dermatology (121:522) reports, dermatologists give an artificial vitamin A-like drug by mouth that, after it is absorbed, darkens the skin in the presence of ultraviolet light (UV), while they administer graded doses of UV. Without such treatment, people who have chronic phototoxicity must permanently avoid the sun.
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