Midol's standard formula has three active ingredients: Acetaminophen, Caffeine, and Pyrilamine maleate (an antihistamine). Acetaminophen is readily available over the counter in both generic and brand names, often cheaper than Midol. Midol claims to be specifically formulated for menstrual pain, specifically cramping. I have been advised by physicians to take Midol when undergoing procedures that might cause cramping outside of my period as well -- the most recent example being to help with uterine cramps caused by insertion of an IUD, which is common advice given before and after the procedure.
Is there any evidence that Pyrilamine maleate (or any similar antihistamine) and/or caffeine reduce the severity, frequency, or duration of menstrual or uterine cramps? Or are those ingredients simply for nebulous mood and fatigue symptoms that can accompany menstruation?