“My complexion is awful” was the complaint of a thirty-four-year-old woman. She had been referred to us for treatment of a facial rash, which had resisted the therapies of a half dozen doctors over the past thirteen years. Several biopsies had been done with the principal finding being intense inflammatory changes around the blood vessels.

Upon examining her, we saw redness, acne-like pimples, some small blisters, and yellow crusts on her face. Her problem had defied not only therapy, but also classification. It wasn't exactly rosacea or acne. We were puzzled, but intensive questioning opened a door of understanding. We asked, “Does it get worse before your menstrual period?” Her answer was, “I have no idea – it's worse all the time.” But several visits later she came in saying, “You know, it really does get worse before my period! I had never noticed that and you are the first doctor to ask me.” We now suspected she was allergic to her own ovarian hormone, progesterone.

Years before we had demonstrated that women could become sensitive to their own progesterone. This hormone can induce a variety of skin changes, including itching, hives, and even water blisters. The clue to progesterone sensitivity is the observation that the problem is always worse just before the period – the time when the highest blood levels of progesterone are found. Once the menses are over, progesterone levels drop and the skin reaction abates.