Sex Differences in Medicine

This biology reaches the pharmacy. The FDA now requires sex-specific dosing for some drugs after finding real harm. Women clear the sleep drug zolpidem more slowly than men, so the standard dose left many of them with next-morning drowsiness behind the wheel. After reports of crashes, in 2013 the FDA cut the recommended dose for women in half.

The pattern shows up in diagnosis too. Chest pain is actually the most common heart attack symptom in both women and men. But women more often have additional symptoms alongside it — jaw or back pain, nausea, crushing fatigue — and are somewhat more likely than men to have no chest pain at all. Because the textbook picture was built around men, these presentations were missed for decades.

The immune system splits as well. Carrying two X chromosomes means more immune-related genes, which gives women stronger defenses against infection but also a higher rate of autoimmune disease, where those defenses turn inward.