Of all the physiological changes we go through every month because of our period, poo is one that often gets overlooked. Chances are you’ve never made the connection, or dismissed it as a cruel coincidence, but there’s an actual biological reason why your bowels go on the fritz when you’re due on. 

Experiencing constipation, diarrhoea, or a double whammy of both before your period is a common occurrence for many. Thought you were the only one? Think again. 

Understandably, period poo is not the sexiest subject, but it’s an important one. Your bowel health says a lot about your overall health, not to mention your quality of life. It’s one of those things that is overlooked until a problem arises, but understanding your bathroom habits is vital—especially in relationship to your menstrual cycle. 

How your bowels and menstrual cycle are linked

Hormonal fluctuations during your cycle don’t just have an impact on when you bleed and how moody you feel, they affect every system in your body, including your digestive system and bowels. 

We still don’t know why hormones affect the GI tract, but we know that its lining contains hormone receptors that are especially sensitive to sex hormones like progesterone and oestrogen. 

These receptors interact with hormones (which are in a constant state of motion throughout your cycle) and regulate body functions—like bowel movements—in response. 

If you have underlying health conditions like endometriosis or IBS, bowel issues are common throughout the whole month, but your symptoms can flare up even more when you’re due on. In fact, women with IBS are more likely to experience bowel disturbances during their period compared to women without any chronic digestive issues.  

Constipation

Do you ever feel constipated during your luteal phase? You can blame progesterone for your poo going MIA. 

About a week before your period, progesterone levels peak to sustain a possible pregnancy (and drop rapidly if an egg has not implanted). It’s believed that a spike in progesterone is the culprit for an onset of PMS symptoms, including bloating and constipation. 

Progesterone acts as a muscle relaxant and decreases contractions in the bowel. Everything slows down, so gas and food takes longer to travel through your intestines, making you feel backed up and gassy. 

To make matters worse, higher levels of progesterone can cause water retention, which in turn makes going to the bathroom even more challenging. 

Many of us also tend to reach for highly processed, fatty and carb-heavy (delicious) comfort foods when we’re PMSing, which doesn’t exactly help an already sluggish digestive system. 

Diarrhoea

Aside from constipation, another common pre-period digestive woe is diarrhoea. Yep, as if bleeding out of your vagina wasn’t enough, your body decides to give you the runs as well. 

Two factors are likely at play, one of them being hormone-like chemicals called prostaglandins,  which stimulate smooth muscle. If an egg isn’t fertilised and a pregnancy won’t be taken place, your uterus seeks revenge and punishes you starts producing more prostaglandins in order to contract (hello, cramps) and shed its lining. 

If your uterus produces more prostaglandins than are needed, these can enter your bloodstream and make their way to the neighbouring smooth muscle in your bowels. There, they have the same contractive affect as they do in your uterus. So, more prostaglandins=more poo.

Both uterine and bowel contractions are caused by this surge in prostaglandins, which can  make it hard to tell where cramps are coming from… it’s like a party in front and in the back. 

A sudden bout of the runs could also be caused by the fact that right before your period comes, progesterone levels drop dramatically, your bowels start contracting more, and things speed up again. All the poo that was backed up while you were constipated is suddenly in a rush to leave your body posthaste. Once again, more poo. 

How to make your bowels chill TF out

These cyclical digestive issues can’t really be prevented, unless you’re on a form of hormonal contraception. Women who use oral contraceptives can avoid some of these symptoms because methods like the combined pill release a steady dose of oestrogen and progesterone throughout the month, avoiding the hormonal fluctuations that trigger period poo.

However, you can still experience GI distress if you take the pill-free break, and we wouldn’t recommend taking hormonal contraception willy-nilly, simply to avoid a bit of constipation. But it’s worth chatting to your doctor about. 

Luckily, there are some things you can do to alleviate symptoms without relying on hormonal contraception. 

If you’re more prone to feeling backed up before your period, you can offset some of constipation by upping your intake of high-fibre foods and water intake mid-cycle, when progesterone starts rising. 

Try to also get your body moving, if you can. Don’t worry, you don’t have to go for a full-on, bootcamp-style HIIT class. Light exercise is very effective in relieving constipation and trapped wind.

If you’re really stuck, you can always go for a gentle over-the-counter laxative or stool softener—but please don’t make this a habit! Laxatives can irritate the stomach lining, which is no bueno for your gut microbiome if taken too often, and you can also become reliant on them (causing worse constipation in the long run). 

If, on the other hand, the arrival of your period gives you the runs, try cutting back on how much coffee you drink (I know, sorry) as caffeine is a natural laxative. Same goes for artificial sweeteners like sorbitol.

It’s also important to keep stress at bay, as stress and anxiety can exacerbate diarrhoea and cramping. When you’re stressed, your brain sends chemical signals to your gut, which can respond by, well, freaking out. 

Monitor your poo

In the same way that tracking your cycle can help you understand and anticipate period symptoms, monitoring your bathroom habits can help avoid some of the bowel discomfort you may experience. 

A good idea is also to keep a journal (although we understand if you CBA to do that). Keep a running track of symptoms based on where you are in your cycle can help you recognise patterns and preemptively plan ahead. 

But mostly? Wait it out. These hormonal fluctuations may be frustratingly regular, but they’re also temporary. Be kind to yourself and take it easy on days when your bowels are being a pain in the ass (literally), and remember they’ll pass soon. 

TL;DR

• It's completely normal to experience GI distress like constipation, diarrhoea and bloating before and during your period.
• Constipation is caused by a spike in progesterone, which slows down digestion and stool from passing through your bowel.
• Diarrhoea is caused by the production of prostaglandins, which cause cramping in both your uterus and bowels.
• Monitoring your bathroom habits during your cycle can help you predict any bowel issues, allowing you to make lifestyle and diet changes to offset some of the most distressing symptoms and discomfort.