Why am I bloated before my period?
You're bloated before your period mostly because of hormone shifts. Changes in estrogen and progesterone make your body hold on to more salt and water, and progesterone slows digestion, which adds gas and constipation. Bloating usually starts a few days to a week before your period and eases within the first couple of days of bleeding.
The three reasons you feel bloated
| Cause | What's happening | What it feels like |
|---|---|---|
| Water retention | Hormone changes before your period affect the system that controls salt and water, so you hold more fluid | Puffy belly, tight rings, swollen ankles, heavier on the scale |
| Slower digestion | Progesterone relaxes smooth muscle, including the gut, so food moves more slowly | Fullness, gas, constipation |
| Prostaglandins | Released as your period starts; they make the uterus and bowel contract | Cramps, looser stools or diarrhea on day 1 or 2 |
Cravings for salty or sugary food in the luteal phase can add to it, as can less sleep and less movement on low-energy days. The extra weight is mostly water, and usually goes within a few days of your period starting. See weight gain before period.
When bloating starts and stops
For most people it builds in the 5 to 7 days before bleeding, peaks on the day before or the first day, and lifts by day 2 or 3. Some feel a smaller bloat around ovulation too. If yours lasts all month, it's probably not PMS.
Drink water (it helps your body let go of fluid), go easy on salty and fizzy foods, take a walk, and try a warm pack. Our full list is in how to reduce period bloating.
PMS bloating or something else?
- Early pregnancy can cause bloating too, because progesterone stays high. Test if your period is late.
- IBS often flares around periods. If bloating comes with pain and bowel changes all month, mention it to your doctor.
- Endometriosis can cause severe bloating with painful periods, sometimes called "endo belly". See endometriosis.
- Ovarian cancer is rare, but persistent bloating most days for 3 weeks or more, especially over 50, needs checking.
For the full symptom guide, see period bloating.
Feeling puffy and uncomfortable can drag your mood down on days that are already harder. Seeing bloating arrive on schedule, and leave on schedule, helps it feel temporary.
See a doctor if you're bloated most days for 3 weeks or more, if bloating comes with weight loss, loss of appetite, feeling full quickly, needing to pee more, blood in your stool, or severe pelvic pain, or if it doesn't follow your cycle.
Frequently asked questions
How long before my period does bloating start?
Usually 5 to 7 days before, sometimes earlier, after ovulation.
Why do I look pregnant before my period?
Water retention plus slower digestion and gas can make your belly look noticeably rounder. It usually settles within a few days of bleeding.
How much weight can you gain before your period?
Often 1 to 2 kg (2 to 5 lb), mostly water, which goes once your period starts.
Is bloating a sign my period is coming?
Yes, for many people it's one of the first signs. See signs your period is coming.
Sources
- NHS: Bloating
- ACOG: Premenstrual Syndrome (PMS) FAQ
- Office on Women's Health: Premenstrual syndrome (PMS)
- Cleveland Clinic: Bloated stomach
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
Period bloating: why it happens and how to ease itPeriod bloating explained: why your tummy swells before and during your period, how long it lasts, and simple, evidence-based ways to feel lighter.How to reduce period bloating: 10 things that helpHow to reduce period bloating: less salt, more water, movement, fiber, potassium-rich foods and the right pain relief. Quick fixes and prevention.Why do I gain weight before my period?Why do you gain weight before your period? Water retention, slower digestion and cravings in the luteal phase. How much is normal and what helps it settle.
PMS test: do my symptoms follow my cycle?Free PMS test: rate 11 common premenstrual symptoms and see whether yours look like mild PMS, typical PMS or something worth raising with a doctor.
Luteal phase foods: handling hunger and cravings kindlyWhat to eat in the luteal phase: why appetite and cravings rise before your period, foods that steady energy and mood, and calcium for PMS.