While up to 75% of females experience PMS symptoms and some kind of discomfort before menstruation, PMS is clinically defined as a range of physical, psychological, and behavioural symptoms that occur in the luteal phase of the menstrual cycle (the two weeks before our period). These symptoms disrupt the way we normally function and interfere with our daily lives, work, school, or relationships. Symptoms typically resolve a few days after we get our period.

Physical symptoms can include cramps, nausea, bloating and body aches. Psychological symptoms can include mood swings, irritability, anger, or anxiety. Behavioural symptoms can include difficulty sleeping, food cravings, and withdrawal. These symptoms typically disappear once our period begins, but can be severe enough to interfere with our daily lives, work, school, or relationships. 

Although pretty uncomfortable, bloating in PMS is very common.

Bloating typically happens in our abdomen and is characterised as a tight, full, and often painful feeling. Sometimes, but not always, our tummy sticks out as a result (called a distended abdomen). Other areas of the body can be affected too, feeling swollen and enlarged, such as the hands, feet and face. 

It’s important to note that bloating isn't always related to PMS, and can also be a result of digestive or gastrointestinal issues like constipation, gut sensitivity, or IBS. It can also be a sign of other gynaecological conditions, including fibroids, ovarian cysts, or ovarian cancer. If your bloating is constant, getting worse, or associated with any unexplained weight loss, abnormal bleeding, change in bowel habits, or severe abdominal pain, speak to your healthcare professional.

Experts don’t know exactly what triggers it, but PMS bloating is likely due to water retention caused by hormone fluctuations occurring during the luteal phase. Bloating typically reduces once we get our period.

Due to the lack of research and funding around PMS symptoms, it’s hard to get a clear-cut picture of just how many people experience bloating. One study which looked at water retention in more than 750 menstrual cycles states that: “many women* perceive changes in fluid retention or ‘bloating’ over the course of their menstrual cycle”. Although we don’t know exact numbers, PMS bloating is very common and you’re not alone if you experience it.

The simple answer is, it depends. Each individual experiences every cycle slightly differently, so you might experience changes in your flow, energy levels, quality of sleep and all the other PMS symptoms from one month to the next, and that includes bloating.

The Mayo Clinic says that: “most women* who menstruate experience symptoms such as bloating one to two days before the start of their periods.” However, with the luteal phase starting just after ovulation and lasting until our period begins, that’s a two-week window in which we could experience bloating. 

Although, with all that said, there is evidence that premenstrual bloating could be a misnomer, and in fact, bloating coincides with our period. Interestingly, one medical study measuring water retention in menstrual cycles found that bloating tended to be at its worst on the first day of the period, rather than in the few days preceding it. Regardless of the trigger (be that PMS or period), experiencing PMS bloat is totally normal.

If you’re looking for ways to calm the pre-period bloat, there are a few things you can do to reduce the discomfort.

1. Avoid foods high in salt and/or sugar

When we’re experiencing PMS or a period, it’s tempting to reach for a big bag of crisps or family-size Galaxy bar. But sodium and refined sugars can lead to increased water retention, which can make PMS bloating worse. As much as you’re able to, resist the temptation to treat yourself to a salty or sugary snack. We know trying to convince you to swap the Kit Kat for a bunch of kale isn’t going to work. But, there are some less-severe substitutions to try. For example, trade the chocolate bar for sliced up a banana dipped in 80-90% cocoa chocolate, or opt for some homemade chips instead of the crinkle-cut crisps. 

‍2. Get moving

When we’re down with PMS symptoms, it can be tempting to stay in bed and take it easy. But, if you have enough energy to be active, it can help to ease PMS bloating. Even taking 15 minutes to do simple stretching or a brisk walk in the park can get your blood flowing and relieve abdominal pressure. Plus, exercise is a wonderful mood booster!

‍3. Step up your self-care

Let’s face it, pre- and during our period isn’t anyone’s favourite time of the month. So to ease the physical and mental strain, practise self-care in any way that feels genuine to you. Indulge in a soothing candle-lit bath or listen to a guided meditation to calm your mind. Or sit in your favourite chair with a book and a big cup of mint tea. Taking more time to rest can help us cope with PMS symptoms.

If none of these is working for you, speak to your GP. They may recommend other lifestyle changes or possibly water pills (diuretics), which can help reduce fluid retention.

In addition to bloating, we might observe other changes to the shape of our bodies in the days before our period arrives. You may notice tenderness in your breasts, constipation or diarrhoea, or acne on your face or back.