Progesterone does nothing to ease premenstrual syndrome (PMS), even though it is the most widely used treatment for it.
Taking progesterone was thought to influence the woman's menstrual cycles, but the theory had never been proven.
Researchers from the University of Pennsylvania carried out a double-blind test on 300 mg of oral progesterone, comparing it with 0.25 mg of alprazolam and a placebo ("sugar pill"), given four times a day from the 18th day of the cycle.
The group taking the alprazolam, a tranquillizer, was the only one to show any noticeable improvement in symptoms, although these included just the mental functions, mood and pain. Physical symptoms, however, were as bad as ever.
Progesterone was no better than the placebo, researchers discovered (JAMA, July 5, 1995).