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Why Does my Tummy Get Upset During my Period?

Digestive issues can be common during your period. WUKA experts discuss what causes it and how to ease your upset tummy.

What causes an upset stomach during your period?

We’ve all been there, and it’s not pleasant. Having an upset tummy just as your period arrives is never fun, but for some it can be a monthly occurrence. So what causes us to have an upset tummy during our period, and why do some of us experience more than just the usual ‘period poop’?


Ah, prostaglandins. These are the chemicals which are responsible for painful period cramps, and they’re more than likely at work when our tummy starts to feel really bad too.

During the first couple of days of menstruation, the uterus works hard to shed its lining, by contracting and squeezing the blood vessels. These contractions cause the blood supply to the uterus to be cut off temporarily, which prompts the release of prostaglandins, which in turn triggers a pain response. 

And according to studies like this one, sometimes these painful cramps are enough to set off a whole cycle of digestive issues as a result- tummy pain, nausea, diarrhoea and other gastro-intestinal symptoms. Not fun.

And Dr. hashi Prasad, a specialist in integrative women's health and bioidentical hormone balancing for the Marion Gluck Clinic, told us:

why do I get an upset tummy during my period?

“Some women can get upset stomach before and during periods. These may present as nausea, abdominal cramps, diarrhoea, bloating. Some may even get constipation. 

This is usually related to a hormone like chemical called prostaglandins. Just before periods the uterus releases these chemicals. It helps the uterus shed the lining and induce a period.  When the levels are high it can also affect the bowel, cause it to cramp and give nausea and loose stools. 


Regarding constipation, it may be related to the progesterone hormone. The levels increase in the second half of your cycle after ovulation. This hormone relaxes the muscles of the bowel and reduce its movements. Hence, resulting in constipation. This usually gets better once periods start. 


Speak to your doctor If your symptoms are bad and affecting your life or if you notice any blood in your stools."

Fluctuating hormones

During your period, levels of progesterone and oestrogen rise and fall sharply, and this can result in many symptoms within the body. Headaches, bloating, acne, muscle aches… a whole range of PMS symptoms. And yes, and upset tummy is one them too.

Poor diet

If your diet is filled with heavily processed foods which are high in salt, sugar, additives and preservatives, your digestive system is going to suffer. Artificial flavouring and colourings are well known cause of gastro upset and if you’re eating a lot them around the time of your period, you might notice an increase in digestive issues.

Dr. Prasad told us that prostaglandins can also affect the foods we eat too:

“ Prostaglandins are also pro-inflammatory.  Hence, food which increases inflammation may cause period cramps to worsen.  This includes ultra-processed food high in sugar, salt, saturated fats, processed meats, refined carbohydrates. Going on an anti-inflammatory nutritional plan can help a lot with this symptom. For e.g., Omega 3 fatty acids, oily fish, lots of vegetables, flax seeds & nuts.”

Gut-brain connection

Scientists believe that there is a very real connection between our brains and our digestive system. This could explain why we often feel ‘butterflies’ in our tummy when we’re nervous or excited, and why we might experience nausea or tummy pain when we’re scared. 

why do I get an upset tummy on my period?

So with this in mind, can certain symptoms of PMS (namely anxiety, stress, mood swings and low mood) be the reason why we might also experience tummy upset? According to this Harvard Medical School article, it could well be. The researchers there have found that the gut-brain connection actually works both ways, with a ‘troubled intestine’ able to send signals to the brain, in the same way that the brain can send signals to the gut. They conclude that “ a person’s stomach or intestinal distress can be the cause or the product of anxiety, stress, or depression.”

This theory is supported by this 2014 study, which found that PMS can impact digestive symptoms, but that intestinal distress can also impact PMS too. Likewise, this study also from 2014 concluded similar, stating that “Emotional symptoms occurring in conjunction with GI symptoms are common perimenstrually, and as such may reflect shared underlying processes that intersect brain, gut, and hormonal pathways.”

Hormonal birth control

Some hormonal birth control methods could negatively impact on your digestive system, causing tummy pain and/ or diarrhoea. Speak to your GP about any symptoms you may be experiencing to find out if it can be linked to your contraception.

How to ease an upset stomach

The good news is that there are plenty of natural remedies you can try at home to ease your upset stomach- whether PMS is to blame or not.

Drink plenty of water

We can’t emphasise enough how important it is to stay hydrated throughout the day, and especially when you have a dodgy tummy. If you suffer with diarrhoea and/ or vomiting, replacing lost fluids is really important. Drink little and often, and if you can get some coconut water down you, then do- it’s a really good way to replace lost electrolytes.

Other drinks that are good for an upset tummy include peppermint or ginger tea too.

Why Does my Tummy Get Upset During my Period?

Healthy diet

Take an honest look at your diet and make an assessment as to whether or not it’s really the healthiest it can be. We advocate for an 80/20 approach, which means that 80% of your diet is healthy and balanced, leaving enough room for 20% that isn’t so healthy, but that is essential for your happiness and emotional wellbeing.

Try to eat less processed foods, especially around the time of your period, and avoid foods that are really high in salt, sugar and artificial flavourings and colourings. It’s a good idea to make sure that every meal has a source of protein, whole grains and healthy fats if you can, and avoid foods that you know will trigger tummy pain too. 

Gentle exercise

Exercise can be an amazing way to ease an upset tummy, and can release endorphins which in turn trigger a boost in serotonin levels. Serotonin is the ‘feel good’ hormone that is known to not only make us feel more relaxed and happy, but that can reduce pain too. 

Make sure you have a good, comfy pair of period pants on hand for your workout, and maybe even a pair of WUKA period leggings to keep you comfy and protected while you get the blood pumping.

Reduce stress

As we’ve already mentioned, stress can be a huge cause of tummy upset and especially during your period when PMS symptoms are likely to strike. Doing what you can to reduce stress can be really helpful, but we know it’s not always easy. Here are our top three tips for reducing stress:

  • Try to take some time out each day just for you. Whether that means just five minutes to meditate, or half an hour to read a book or take a warm bath. Create some space for your own relaxation and emotional wellbeing.
  • Talk to someone. The old saying, ‘a problem shared is a problem halved’ has never been more true, so if it feels good to offload on someone, then do it. You can also write it down too- journaling is great for getting all your feelings out on paper so you can mentally move on from them at the end of the day.
  • Take a digital de-tox. One quick scroll through social media, and its easy to see why we’re so stressed! Sometimes we all need to take a break, knowing that our feed will still be there waiting for us when we return. Get outside for a walk- without your phone- now and then. It might just do you the world of good. 

Related posts

What are Period Cravings?

Why do I Poo More on my Period?

Period Bloating 

Period Flu



Why is my tummy so upset during my period?

There can be many reasons why you get an upset tummy during your period. It could be down to diet and lifestyle, hormones, your method of birth control or PMS symptoms. To ease your tummy upset, try maintaining a healthy, balanced diet with lots of water and some gentle exercise. 

Speak to your GP if you’re concerned about digestive issues you might be experiencing.

How do you stop a period upset tummy?

There are plenty of natural remedies that you can try to ease an upset tummy. Avoid foods that you know are likely to make you feel worse, and steer clear of processed foods too. Foods that are high in sugar, salt, or artificial flavourings and preservatives can cause inflammation, which can lead to tummy upset too. 

It’s also a really good idea to take steps to reduce stress in your life, as this is know to make digestible issues worse too.