Period bloating or gut bloating? How to tell on a calendar

Period bloating keeps to a timetable: it tends to build in the days before a period and its first days, then ease off. Gut bloating follows meals, your bowels and stress. Mark your bloating days on a calendar for at least two cycles to see which you have. Bloating on 12 or more days a month needs a GP.

You can have both at once, which is why the calendar matters more than the label.

Why do periods make you bloated?

Nobody fully knows, but it is common. Bloating or cramping is one of the most common symptoms of PMS, the name for the symptoms that come in the weeks before a period, and why PMS happens is not fully understood. Changing hormone levels across the cycle may be behind it, and some people are more affected by those changes than others.

The gut is part of it. In a Canadian survey of 156 healthy women, 73% had at least one gut symptom, such as tummy pain or diarrhoea, in the 5 days before or during their period. A review of the research found gut symptoms, bloating among them, rising before and during periods in women with and without IBS, at the points in the cycle when hormone levels are low or falling.

Not every study agrees. A 2023 survey of 603 young women found their overall gut symptom scores did not change across the cycle. That is part of why your own calendar is worth more than any general rule.

Can IBS get worse around a period?

For some people, yes. In women with IBS, period related symptoms such as cramping tend to be more intense, and one study found sensitivity to gut pain was higher during a period than at other points in the cycle. So a gut that bloats after meals all month can bloat more in period week, and a calendar will show both patterns at once.

How do I keep the calendar?

Start on day 1, the first day of bleeding, and give every day a line. A cycle commonly runs anywhere from 21 to 35 days, and a period from 2 to 7, so expect your calendar to be your own shape rather than a neat 28.

Each day, note:

• a bloating score from 0 to 3, morning and evening
• what you ate, roughly, and anything that felt like a trigger
• your poo: normal, hard, loose, or none
• stress and sleep, in a word
• whether you are bleeding

Do it for at least 2 cycles, which is what the NHS suggests for a PMS symptom diary, and take it with you if you see a GP.

How do I read it?

Line the cycles up by day 1 and look for where the high scores sit.

What else can follow the menstrual cycle?

Endometriosis, for one. Its symptoms can be similar to IBS, and they include severe period pain that stops you doing your normal activities, heavy periods, pain in the lower tummy and back, pain when you poo or pee, pain during or after sex, and extreme tiredness. The NHS says to see a GP if you think you might have it, or if what a GP has tried has not helped. It can take a long time to diagnose, so the calendar is useful here too.

Ovarian cancer does not follow the cycle, and that is what makes the calendar useful against it. The NHS lists its main symptoms as these, happening frequently, roughly 12 or more times a month:

• “a swollen tummy or feeling bloated”
• “pain or tenderness in your tummy or the area between your hips (pelvic pain)”
• “no appetite or feeling full quickly after eating”
• “an urgent need to pee or needing to pee more often”

Its list of other symptoms includes “unusual bleeding from the vagina, including between periods, heavier periods or after the menopause”. See a GP if you have any of these, and go back if “you have previously seen a GP, but your symptoms have not gone away, are worse or more frequent”. Tell the GP if anyone in your family has had ovarian or breast cancer.

If you are 50 or over and IBS type symptoms have appeared for the first time in the last year, NICE asks GPs to test for ovarian cancer, because IBS rarely starts at that age. And if your periods are changing or have stopped, the calendar gets harder to read, which I cover in bloating in perimenopause.

What helps period bloating?

The NHS suggestions for PMS are ordinary ones: regular exercise, a healthy balanced diet, with smaller meals every 2 to 3 hours if you find that suits you, plenty of sleep, something to bring stress down such as yoga or meditation, not smoking, and not drinking too much alcohol. Supplements are often sold for PMS, and the NHS says there is not much evidence that they work.

See a GP if lifestyle changes have not helped or your symptoms affect your daily life. A GP can talk you through other options, and your two cycles of notes give them something to work from. What to tell your GP about gut symptoms helps you get the most from that appointment.

If your calendar points to your gut rather than your cycle, the bloating quiz suggests where to start, and bloating that will not go away covers the patterns that should not wait for another month of notes.