In short

Period diarrhea is common and has a clear biological explanation. In the days leading up to and during a period, the uterus releases chemicals called prostaglandins to help it contract and shed its lining. 

These same chemicals can also affect the bowel, causing it to contract more than usual, which leads to loose stools, cramping, or more frequent trips to the toilet. 

It is not a sign anything is wrong, and it usually eases after the first couple of days.

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What causes diarrhea during a period?

The main culprit is prostaglandins, hormone-like chemicals produced by the cells lining the uterus. Just before a period begins, prostaglandin levels rise to trigger contractions that help expel the uterine lining.

When prostaglandin levels are high, some of these chemicals enter the bloodstream and reach the bowel. 

They stimulate contractions there too, which can speed up the movement of contents through the digestive system and lead to loose stools or diarrhea.

Is it normal to get bowel symptoms with a period?

Yes, this is a very common experience and is a normal response to hormonal changes.

Symptoms can include:

• Loose stools or diarrhea, particularly in the first one to two days
• Cramping in the lower abdomen
• Bloating and gas
• More frequent bowel movements
• Nausea

These symptoms usually ease as the period progresses and prostaglandin levels drop.

What can help?

A few things can reduce the impact of period-related bowel symptoms:

• Anti-inflammatory painkillers for teen period cramps, such as ibuprofen, can reduce prostaglandin activity, which may help with both cramps and bowel symptoms
• Staying well hydrated is important, especially if diarrhea is frequent
• Avoiding foods that tend to aggravate the gut in the days before a period, such as very fatty foods, caffeine, and alcohol
• Eating smaller, more regular meals rather than large ones

When should I be concerned?

Period-related diarrhea is usually mild and short-lived. Speak to a doctor if:

• Bowel symptoms are severe or last throughout the whole period
• There is blood in her stools
• She has significant pain when opening her bowels
• Symptoms are worsening over time rather than improving
• She has diarrhea or bowel pain at other times in the cycle

Severe or persistent bowel symptoms around periods can sometimes be associated with endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus.  This is worth ruling out if symptoms are significant.

FAQ

Why are period symptoms worse some months than others?

Prostaglandin levels can vary between cycles, which means bowel symptoms may be more pronounced in some months than others. 

Stress, diet, and sleep can all affect how the body produces and responds to prostaglandins.

Does ibuprofen help with period diarrhea?

Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) that works in part by reducing prostaglandin production. 

This means it can ease both period cramps and some of the associated bowel symptoms. It works best when taken before symptoms start rather than after.

Can my daughter take anti-diarrhea medicine?

Over-the-counter remedies like loperamide can reduce frequency, but they do not address the underlying cause. 

They may be useful if bowel symptoms are severe enough to disrupt a school day, but are not needed for mild symptoms. If she relies on them regularly, it is worth mentioning to a doctor.

For more on period comfort, luna's article on tips for teenage period pain relief and best foods to eat on a period may be helpful.

Rated 4.8

Period tracking & more for teens. Guidance for parents.

Find out more