Bowel habits commonly change around menstruation, often resulting in loose stools or diarrhea, informally known as “period poops.” This digestive shift is a normal physiological occurrence linked directly to the body’s reproductive cycle. About a quarter of people who menstruate report experiencing diarrhea during their period, highlighting the close link between the reproductive and gastrointestinal systems. Understanding the specific chemical messengers involved explains this monthly digestive reaction.
The Hormonal Mechanism: Prostaglandins
The primary driver of diarrhea during your period is a group of lipid compounds called prostaglandins, which act like local hormones. These substances are produced by cells in the uterine lining just before and during menstruation. Their main function is to cause the smooth muscle of the uterus to contract, helping it shed its lining, which results in menstrual bleeding and cramps.
When the body produces a high quantity of these chemicals, some prostaglandins enter the bloodstream and circulate beyond the uterus. They travel to other nearby smooth muscle tissues, including those lining the digestive tract. The intestines react by increasing muscular contractions and motility.
This hyperactivity causes food and waste to move through the digestive system much faster than usual. Prostaglandins also contribute to diarrhea by increasing the secretion of electrolytes and water into the intestines, resulting in looser, more frequent stools. Prostaglandin E2 (PGE2) is particularly implicated, as it also weakens the gut lining and triggers fluid release into the bowel.
Related Menstrual Digestive Changes
While prostaglandins explain the onset of diarrhea, the entire menstrual cycle affects the gastrointestinal tract through other hormonal fluctuations. In the days leading up to menstruation, progesterone levels are high. Progesterone acts as a smooth muscle relaxant, slowing down the movement of food through the digestive system.
This slowing effect often leads to premenstrual symptoms like constipation, bloating, or gas. When progesterone levels suddenly drop as menstruation starts, the digestive system’s motility rapidly increases. This shift explains why it is common to cycle between pre-period constipation and period-related loose stools.
Practical Strategies for Symptom Relief
Several steps can help manage increased bowel activity during your period. Taking a nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, a day or two before your period starts can be effective. NSAIDs inhibit prostaglandin production, reducing both uterine cramps and intestinal contractions.
When experiencing loose stools, simplify your diet to include gentle, binding foods like bananas, rice, applesauce, and toast (the BRAT diet). It is also helpful to temporarily avoid known digestive irritants:
- Caffeine.
- Alcohol.
- Spicy foods.
- High-fat meals.
Staying properly hydrated is important, as frequent loose stools lead to fluid and electrolyte loss. Replenish lost fluids by drinking water, low-sugar electrolyte solutions, or salty broths. Over-the-counter anti-diarrheal medications are also an option for short-term relief, but they should be used sparingly and according to package directions.
When to Seek Medical Advice
While menstrual-related changes in bowel habits are common, certain symptoms require medical attention. Consult a healthcare provider if your diarrhea is severe, frequently interferes with daily life, or persists long after your period ends. Cyclical symptoms that are painful or worsening over time also warrant evaluation.
Specific red flags include:
- Blood or mucus in your stool.
- Unexplained weight loss.
- Severe abdominal pain not relieved by over-the-counter medication.
These symptoms could indicate other gastrointestinal issues or conditions like Irritable Bowel Syndrome (IBS) or endometriosis. A doctor can determine if your symptoms are hormonal or require treatment for a separate condition.