Many people notice that their bowel habits change predictably throughout their monthly menstrual cycle. This shift in pattern is because the bowel is affected by period-related hormone changes.

During each menstrual cycle, the body goes through many hormonal shifts. These changes affect the whole body, leading to familiar premenstrual syndrome (PMS) symptoms such as mood swings, cramps, and digestive changes.

Bowel movement changes during menstruation can include constipation, diarrhea, or more frequent bowel movements. One study reported that 73% of females experienced period-related gastrointestinal symptoms. Some people describe these changes as "period poop."

In this article, we look at possible reasons why periods can affect bowel movements and some tips for managing the symptoms.

The following sections discuss the bodily changes that occur just before or during a menstrual period that may affect bowel movements.

Increased muscle contractions

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A person may experience muscle contractions just before their period.

Just before menstruation, the body releases hormones known as prostaglandins. These hormones stimulate muscle contractions in the uterus. These contractions help the body to shed the uterus lining.

At the same time, the period hormones may stimulate muscle contractions in the intestines and bowels, which are close to the uterus, causing more frequent bowel movements. They also reduce how well the body absorbs water, making the stool softer and increasing the risk of diarrhea.

It can be difficult to tell the difference between uterus cramps and stomach or intestinal cramps at this time. Both may be uncomfortable or painful.

Prostaglandins are also involved in many other PMS symptoms, including headaches.

Increased progesterone

Progesterone is another hormone that increases right before a menstrual period. For some, progesterone can affect the gastrointestinal tract to cause either constipation or diarrhea.

In females who have chronic bowel issues or an irritable bowel disorder (IBD), such as ulcerative colitis or Crohn's disease, menstruation can make symptoms worse.

For example, in people with IBD-related constipation, progesterone-associated changes can make constipation worse. This is also true for people with conditions such as endometriosis, uterine fibroids, and ovarian cysts.

Furthermore, people with IBD are more likely to experience other PMS symptoms, such as headaches or menstrual pain.

Dietary changes

Progesterone may increase feelings of hunger and can cause cravings for foods high in fat or sugar, such as ice cream or chocolate. The body has a hard time digesting these foods, and eating more of them can affect a person's bowel movements.

PMS-related changes in dietary habits may contribute to why some people notice differences in the consistency, regularity, or smell of their stool before or during a period.

Increased stress or anxiety

During PMS or the menstrual period, many people experience mood swings or increased anxiety levels. Stress can also affect a person's bowel movements, causing constipation or diarrhea.

According to research appearing in the journal BMC Women's Health, people report greater sensitivity to pain and discomfort in the premenstrual phase as well as on their periods. This sensitivity can exacerbate symptoms, too.

An individual cannot always alter how their body reacts before and during a menstrual period. However, diet and lifestyle changes can reduce the risk or impact of stomach upset, constipation, or diarrhea.

The following tips may help people better manage period-related digestive disturbances:

  • Eat plenty of natural fiber, including fruits, vegetables, and whole grains. High fiber foods help keep the digestive system regular.
  • Do something physical. Moving around can help to relieve PMS-related bloating and discomfort and helps keep the bowel moving.
  • Try stool softeners. Stool softeners help stool to pass through the bowel more easily until hormone levels even out.
  • Take ibuprofen. Not only can ibuprofen help to reduce uterus cramping and discomfort, but it is also a prostaglandin inhibitor. Sometimes, this effect may help to take the edge off period-related digestive symptoms.

If period-related bowel disturbances get in the way of a person's daily life, they can talk to their doctor about the best treatment options. Hormonal birth control, such as the oral contraceptive pill, can reduce PMS in some individuals by helping to regulate hormone levels.

Some people choose to take the pill continuously and avoid having periods at all. They should always talk to their doctor first before using this approach.

Period-related bowel changes can be unpleasant, but they usually end as the period ends. If home treatments do not help, a doctor may recommend medication for an underlying issue or hormonal treatments.