Why do I get bloated before my period?

Bloating in the days before a period is one of the most common premenstrual symptoms. The NHS lists "bloating or cramping" among them, and MedlinePlus says most women have at least some symptoms of PMS, with bloating and weight gain among the physical ones. It usually eases once the period starts. What this page cannot do is tell you whether your bloating is typical for you, so it sticks to what the sources say is common, what helps, and when it is worth raising with a doctor.

What the sources say

• It is a recognised premenstrual symptom. The NHS and MedlinePlus both list it, alongside breast tenderness, headaches, mood changes and tiredness.
• Timing. MedlinePlus says symptoms of PMS occur in the five days before a period and end within four days after it starts. The NHS describes them as coming in the weeks before a period.
• Bloating has other causes too. The NHS says the most common reason for bloating in general is gas in the gut, and that digestive conditions such as constipation, food intolerance, coeliac disease and irritable bowel syndrome can also be responsible. Some women feel bloated around their period, but a pattern that does not follow your cycle points somewhere else.

What may help

The NHS suggests regular exercise, a balanced diet, smaller meals every 2 to 3 hours, plenty of sleep and cutting back on alcohol. For bloating itself it adds drinking plenty of water, chewing with your mouth closed to swallow less air, and limiting fizzy drinks, caffeine and foods that produce a lot of gas. MedlinePlus advises cutting back on salt, caffeine, sugar and alcohol in the two weeks before your period. If you are thinking of taking a supplement such as calcium or vitamin B6, MedlinePlus says to check with a provider first.

Keep a symptom diary

The NHS recommends keeping a symptom diary for at least two cycles before seeing a GP, because it shows whether symptoms really follow your period. Writing down the day the bloating starts and the day it stops, next to your period dates, is the simplest way to do that. A period tracker built for Muslim women does this alongside your prayer and fasting record, and Nisaa is free on the App Store.

When to speak to a doctor

• The NHS says to see a GP if your symptoms affect your daily life or lifestyle changes have not helped, and MedlinePlus says the same if they bother you.
• The NHS says to see a GP if you feel bloated regularly, if you have bloating with weight loss you cannot explain, or if you have bloating and blood in your poo.
• The NHS says bloating that does not go away can sometimes be a sign of something more serious, such as ovarian cancer, so persistent bloating is a reason to get checked and not to wait.
• The NHS advises an urgent GP appointment or a call to NHS 111 for bloating with vomiting, a stomach ache, a fever, or a swelling or lump in your tummy, and emergency care for a sudden, severe stomach ache with a swollen stomach.

Related symptoms

Bloating rarely arrives alone. If it comes with other changes, see why your breasts hurt before your period, why you get mood swings before your period, why you get headaches before your period and what actually relieves period cramps. For how long a cycle should be, so you can tell when your period is due, see how long a cycle should be.