Period Symptoms

Period Poop, Bloating, Diarrhea, and Constipation: What Is Actually Happening

Prostaglandins make your uterus contract during menstruation, but they also make your bowels contract. Progesterone slows your gut in the days before your period. The result is a predictable cycle of constipation, then diarrhea, then bloating that 73 percent of menstruating women experience. Here is the science behind it and what actually helps.

Last updated 2026-04-25

Current Consensus

  • Prostaglandins released during menstruation stimulate both uterine and intestinal smooth muscle contractions, causing diarrhea and cramping in many women (Bernstein et al., 1996).
  • Progesterone slows gastrointestinal transit during the luteal phase, contributing to constipation and bloating in the week before menstruation.
  • Approximately 73 percent of menstruating women experience at least one GI symptom before or during their period (Judkins et al., 2020).
  • Period-related bloating is caused by a combination of water retention from hormonal shifts and slowed gut motility, not gas production alone.
  • NSAIDs like ibuprofen reduce prostaglandin production and can alleviate both menstrual cramps and period-related diarrhea.

Open Questions

  • Whether individual variation in prostaglandin receptor density explains why some women have severe period diarrhea while others do not.
  • The degree to which gut microbiome composition modulates the severity of menstrual GI symptoms.
  • Whether cycle-specific dietary interventions (e.g., lower FODMAP in the luteal phase) produce clinically meaningful symptom reduction.
  • How hormonal contraceptives that suppress ovulation and menstruation affect long-term gut motility patterns.
  • The interaction between pre-existing IBS and menstrual cycle hormones in amplifying GI symptoms.

Medical Disclaimer: The content in this section is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional before making changes to your health regimen. GLP1Gut is a tracking tool, not a medical device.