“Why do I have these brown spots?” was the query of a thirty-seven-year-old woman. She didn't seem too hopeful of getting an answer. She had made innumerable visits to her family doctor and to emergency rooms over the past three years. No one knew why she had had that large brown area over her left hip all that time. And another big brown patch had appeared on her right knee just one year ago.

We asked, “but why the emergency room visits?” “Oh, every four to five months those brown spots get swollen, terribly red, and hurt bad.” We then knew what it was – a fixed drug eruption. Every one of her alarming attacks over the past three years had to have been preceded by her taking the same troublemaker drug.

What drug was it? In most patients the search can be lengthy. There is no blood test. An oral challenge is necessary, although in a few patients simply applying the crushed pill or liquid medicine over the brown spot will set off a local red reaction, thus identifying the cause. In most instances the best detective work is done by the patient, once informed and on the outlook for what she or he has taken the day before the “fire” comes into the brown spots. The patient must realize that in some instances the red flare-up is slight, totally obscured by the residual brown pigment from past attacks.