Why do I get diarrhea on my period?

Apart from very well-known symptoms like stomach cramps, your period may also be accompanied by digestive distress, such as constipation or diarrhea before or during your menstrual cycle. There are various reasons for period diarrhea, the most common of which are prostaglandins—chemicals that trigger muscle contractions in the uterus and digestive tract. We’ll cover other possible causes of period diarrhea, provide tips for treating and preventing it, and let you know when it’s time to see a doctor. 

Why can your period cause diarrhea?

A BMC Women’s Health study suggests that approximately one-third of women experience changes in bowel habits, including diarrhea and constipation, during their period. Although experts are not sure of the exact reasons for diarrhea during menstruation, some possible explanations include high prostaglandin levels, heightened sensitivity to hormonal fluctuations during the menstrual cycle, endometriosis, and gastrointestinal conditions, such as inflammatory bowel disease (IBD) and inflammatory bowel syndrome (IBS).

High levels of prostaglandin

Period diarrhea may be caused by the release of prostaglandins, according to The American College of Obstetricians and Gynecologists. Prostaglandins are hormone-like substances produced in the uterine lining, and they cause the muscles and blood vessels of the uterus to contract. Its levels are highest on the first day of your period and reduce as the bleeding stops. 

“Higher levels of prostaglandins can lead to stronger uterine contractions, which may not only result in cramps but also affect the nearby intestines, leading to diarrhea,” says Karen Toubi, a board-certified OB-GYN in Beverly Hills, California. The mechanism behind the role of prostaglandins in period diarrhea is not well understood, but one study suggests that prostaglandins trigger contractions of smooth muscles in the gastrointestinal (GI) tract, which then leads to diarrhea symptoms—softening stools and increasing the number of stools or watery stools.

Heightened sensitivity to hormonal changes

Experts hypothesize that sensitivity to fluctuations in reproductive hormones may play a role in period-related diarrhea. Women experience changes in hormone levels, including reproductive steroids—progesterone and estrogen—throughout the menstrual cycle. Individuals react differently to these hormonal fluctuations. For example, some women who experience increased sensitivity to the fluctuations in hormones are likely to experience period diarrhea. 

“It’s important to recognize that individual responses to hormonal changes can vary widely, and not everyone will experience period diarrhea or other gastrointestinal symptoms. Factors such as genetics, overall health, and the presence of conditions like endometriosis can also contribute to the variability in symptoms,” Dr. Toubi says. 

Heightened sensitivity to hormonal fluctuations has also been associated with psychological symptoms such as anxiety, mood swings, and depression. According to BMC Women’s Health, women who had GI symptoms like period diarrhea also presented with depressive symptoms. 

“Research in this area is ongoing, and gaining a more comprehensive understanding of the interplay between reproductive hormones and gastrointestinal function during the menstrual cycle may lead to improved management and treatment options for individuals experiencing period-related symptoms,” Dr. Toubi says.

Inflammatory bowel disease

Women with IBD are more likely to report GI symptoms like diarrhea during their period. Some researchers argue that these GI symptoms may be linked to prostaglandins. People with IBD already have increased gut motility, which is more severe during their menstrual period because of increased prostaglandin levels. Hence, prostaglandins, which are associated with increased pain and gut motility, may contribute to the worsening of IBD symptoms like diarrhea and cramps during menstruation.  

Irritable bowel syndrome

Women with IBS also report worse GI symptoms, particularly period diarrhea, during menstruation. Studies suggest that women with IBS have a higher likelihood of experiencing flatulence, diarrhea, constipation, abdominal pain, and nausea before and during their menses.

Endometriosis

Period diarrhea and dysmenorrhea (painful menstruation) are possible risk factors for peritoneal endometriosis, which is when endometrial tissue is found on the lining of the abdominal wall. “Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside the uterus. It can cause pelvic pain, heavy menstrual bleeding, and gastrointestinal symptoms, including diarrhea. The exact mechanisms are not fully understood, but it is believed that the presence of endometrial tissue outside the uterus can produce inflammatory substances, including prostaglandins, which may contribute to diarrhea,” Dr. Toubi says. 

Symptoms of endometriosis include:

• Chronic pelvic pain
• Heavy bleeding during periods or between periods
• Infertility
• Bloating or nausea
• Fatigue
• Depression or anxiety
• Pain during or after intercourse
• Pain during urination or defecation
• Changes in bowel movements

If period diarrhea is accompanied by any of the above symptoms, see your healthcare provider immediately to rule out endometriosis.

How to manage diarrhea during your period

Periodic diarrhea can be very inconvenient, but it is manageable. Here are a few tips and lifestyle changes for managing diarrhea during your period:

• Choose your meals wisely. Limit foods and drinks containing caffeine, salt, and sugar two weeks before your period because this may help reduce premenstrual syndrome (PMS) symptoms, according to the Office on Women’s Health. Following the BRAT (bananas, rice, applesauce, and toast) diet can also help prevent diarrhea. BRAT is an acronym for bananas, rice, applesauce, and toast. White rice and white toast are recommended over brown rice and whole wheat toast because their high-fiber content can irritate the stomach when you have diarrhea. Keep in mind that the BRAT diet is meant for short-term use since it lacks essential nutrients, such as calcium, protein, vitamin B12, and fiber. 
• Focus on hydration. Diarrhea can cause dehydration, so be sure to drink plenty of water or low-sugar drinks infused with electrolytes during that time of the month. Avoid fizzy drinks and drinks with caffeine, which could irritate the gastrointestinal tract and cause diarrhea. 
• Try antidiarrheal medicines. Antidiarrheal medicines, such as Immodium A-D (loperamide) and Pepto-Bismol (bismuth subsalicylate), can reduce the frequency of loose stools during your period.
• Get enough sleep. This is particularly important if period diarrhea is accompanied by depressive symptoms. The Office on Women’s Health suggests that sleep deprivation is associated with PMS symptoms, such as depression and anxiety.
• Take probiotics. Probiotics (found in foods like yogurt, sauerkraut, and kefir) are rich in microorganisms that can restore friendly bacteria in your digestive system.
• Try zinc supplements. The World Health Organization recommends zinc supplements for treating severe diarrhea. They can also reduce the severity of cramping, according to research on the effect of zinc consumption in people with painful menstruation. However, talk with your healthcare provider before taking any supplements.
• Take nonsteroidal anti-inflammatory drugs (NSAIDs). “NSAIDs, such as ibuprofen, can help reduce the production of prostaglandins and alleviate symptoms like cramps and diarrhea. Again, it’s crucial to use these medications under the guidance of a healthcare provider,” Dr. Toubi says.
• Apply a heating pad. “Applying heat to the lower abdominal area may help relax muscles and alleviate cramps and discomfort,” Dr. Toubi suggests. 

Most importantly, see a doctor if period diarrhea is accompanied by other clinical symptoms

The causes of period diarrhea include individual sensitivity to hormonal fluctuations during the menstrual cycle, high levels of prostaglandins, and chronic diseases, such as IBD, IBS, and endometriosis. However, if period diarrhea continues, worsens, or is accompanied by chronic pelvic pain, heavy bleeding, painful urination, painful sex, anxiety, or depression, it may be a sign of endometriosis. Your gynecologist or primary care provider can rule out endometriosis and recommend an appropriate treatment. If you have a history of IBD or IBS, you should also reach out to your healthcare provider for recommendations on how best to manage the exacerbated GI symptoms during your period.