Can menstrual periods cause diarrhea?

Can Menstrual Periods Cause Diarrhea?

Yes, menstrual periods commonly cause diarrhea in healthy women, and this symptom is significantly more pronounced in women with pre-existing bowel conditions.

Prevalence in Healthy Women

• Approximately 28-34% of healthy menstruating women without any bowel disorders report diarrhea during their menstrual periods 1, 2.
• This represents a normal physiological response to menstruation and is not inherently pathological 1.

Mechanism and Timing

• Diarrhea typically occurs during the menstrual phase itself (days of bleeding) rather than premenstrually 2, 3.
• The underlying mechanism involves prostaglandins released during menstruation, which stimulate uterine contractions but also affect intestinal smooth muscle, increasing gut motility and causing loose stools 3.
• Women may also experience increased bowel gas and abdominal bloating during menstruation 1.

Enhanced Symptoms in Women with Bowel Disorders

Women with inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS) experience significantly worse diarrhea during menstruation compared to healthy controls:

• Crohn's Disease: 59.6% report diarrhea during menses (compared to 28.2% of healthy controls), and 47.7% report premenstrual diarrhea 2.
• Ulcerative Colitis: 42.5% report diarrhea during menses 2.
• IBS Patients: These women are significantly more likely to experience exacerbations of bowel symptoms, particularly increased gas and diarrhea, during menstruation compared to women without IBS 1, 4.
• Women with IBS report the most severe limitation of daily activities and lowest quality of life during the menstrual phase compared to other cycle stages 4.

Clinical Implications

• Menstrual-related diarrhea is not associated with psychological traits or increased somatization—it represents a genuine physiological phenomenon 1.
• The symptom pattern does not correlate with specific hormonal phases (follicular vs. luteal) in terms of orocaecal transit time, suggesting the effect is primarily prostaglandin-mediated rather than sex hormone-mediated 5.
• Some women with constipation (approximately 50% of constipated patients) actually report improvement in their bowel symptoms just before or during menstruation 5.

When to Investigate Further

While menstrual-related diarrhea is common and typically benign, consider additional evaluation if:

• Diarrhea persists beyond the menstrual period or occurs at other times in the cycle 6.
• Constitutional symptoms are present (fever, weight loss, blood in stool) 6.
• There is a sudden change in bowel pattern or new onset of symptoms 6.