Why do I get period poops? How hormones affect your gut

Feeling like your bowel movements have slowed down in the days before your period, and then things speed up once it starts? You are not alone. Changes in bowel habits across the menstrual cycle are very common. Here is how hormones can impact your gut around your period.

In one study of healthy women, around 3 in 4 reported at least one gut symptom before or during their period.¹ These changes are common and are thought to be linked to the normal shifts in hormones across the cycle.

Which gut symptoms are common?

The most common gut symptoms reported before and during a period include:¹

• Abdominal pain
• Bloating
• Looser bowel movements or diarrhoea
• Constipation
• Nausea

Everyone's experience is different, and symptoms can change from cycle to cycle.

Why is constipation common before your period?

After ovulation, progesterone rises during the second half of the cycle. Progesterone relaxes smooth muscle, including the muscles in the gut wall. This may slow down how quickly food moves through the gut, which can lead to harder stools, constipation and bloating in the days before a period.²

Not all studies have found this effect, and not everyone experiences it, but it is one of the main explanations researchers have suggested.

Why are looser bowel movements common during your period?

Just before and during a period, progesterone drops and the lining of the uterus releases prostaglandins. Prostaglandins cause the uterus to contract, which helps shed the lining, and they are a key cause of period cramps.

Prostaglandins are also thought to act on the bowel, which sits close to the uterus. This may lead to looser bowel movements, diarrhoea and abdominal cramping.¹ The drop in progesterone may also allow the gut to move more quickly again.

Other factors that may play a role

Mood, stress and the gut brain connection

In the same study, women who experienced low mood or anxiety around their period were more likely to report gut symptoms.¹ This may reflect the close connection between the gut and the brain.

Changes in eating

Appetite and cravings often change before a period. Shifts in the types and amounts of food eaten, as well as changes in sleep and movement, may also affect bowel habits.

IBS and endometriosis

People with IBS often notice their symptoms get worse around their period.³ Bowel symptoms that flare with periods, particularly with significant pain, can also be a sign of endometriosis. If this sounds familiar, it is worth speaking with your GP.

What can help

In the days before your period

• Eat regularly, which helps support a regular bowel routine.⁴
• Stay hydrated, as fibre works best with plenty of fluid.⁴
• Include fibre rich foods, such as oats, whole grains, legumes, vegetables, fruit, nuts and seeds. Increase fibre gradually to avoid extra bloating.⁴

During your period

• Include soluble fibre, such as oats, chia seeds, banana or sweet potato, which can help firm up looser stools.⁴
• Notice whether caffeine, alcohol, spicy or rich, fatty foods make symptoms worse for you.

Track your symptoms

Tracking your gut symptoms alongside your cycle for a few months can help you spot patterns. It can also be useful information to share with your GP or dietitian.

When to see your GP

Some changes in bowel habits around your period are common. However, it is a good idea to see your GP if your symptoms are severe, affect your daily life, continue outside your period, or if you notice blood in your stool.

Want support with gut symptoms across your cycle?

Nula Nutrition can support you to understand your symptoms and find an approach that works for you, including IBS and endometriosis. The approach is always evidence based and tailored to you. Registered dietitian consultations are available for women's health in Calgary and online across Alberta, including Canmore, Banff, Edmonton, and Cochrane.

Ready to get personalised nutrition support?

Book a Free Discovery Call

Please note: This post is intended for general educational purposes only and does not constitute personalised medical or dietetic advice. If you have new, severe or changing gut symptoms, please see your GP.

Written by Madison Hows RD APD

References

1. Bernstein MT, Graff LA, Avery L, Palatnick C, Parnerowski K, Targownik LE. Gastrointestinal symptoms before and during menses in healthy women. BMC Womens Health. 2014;14:14.

2. Wald A, Van Thiel DH, Hoechstetter L, et al. Gastrointestinal transit: the effect of the menstrual cycle. Gastroenterology. 1981;80(6):1497-1500.

3. Heitkemper MM, Chang L. Do fluctuations in ovarian hormones affect gastrointestinal symptoms in women with irritable bowel syndrome? Gend Med. 2009;6(Suppl 2):152-167.

4. McKenzie YA, Bowyer RK, Leach H, et al. British Dietetic Association systematic review and evidence-based practice guidelines for the dietary management of irritable bowel syndrome in adults (2016 update). J Hum Nutr Diet. 2016;29(5):549-575.