Menstrual phase: what happens on your period

What happens in the menstrual phase

Day 1 of your cycle is the first day of real bleeding (not spotting). In the luteal phase before it, the corpus luteum (what's left of the follicle after ovulation) was making progesterone to keep the uterine lining thick. When no pregnancy happens, it shrinks after about two weeks. Progesterone and estrogen fall, the lining loses its support, and it sheds through the cervix and vagina as your period.

At the same time, the next cycle is already starting. Low estrogen tells the brain to release more follicle-stimulating hormone (FSH), which wakes up a new group of follicles in the ovaries. So the menstrual phase is both an ending and a beginning: it sits inside the start of the follicular phase.

How long does the menstrual phase last?

According to the NHS, a period lasts 2 to 7 days, usually about 5, and the heaviest bleeding is normally in the first two days. Most people lose 20 to 90 ml of blood across the whole period, roughly 1 to 5 tablespoons. It often looks like more because the flow contains lining tissue and fluid as well as blood.

Common menstrual phase symptoms

• Cramps in the lower belly, back or thighs. They usually start just before or as bleeding begins and ease within 2 to 3 days.
• Tiredness, from low hormones, poor sleep, pain and, with heavy periods, iron loss.
• Bowel changes: prostaglandins can cause looser stools or more frequent trips to the toilet.
• Headaches, including menstrual migraines linked to the drop in estrogen.
• Bloating and sore breasts that started in the luteal phase usually ease in the first days.
• Mood: many people feel relief as PMS lifts; some feel low, flat or more inward for a day or two.

Mood and energy on your period

For lots of people, the start of the period is when the luteal cloud lifts. The PMS rule doctors use says symptoms should end within about four days of bleeding starting. But it isn't relief for everyone. Pain, broken sleep and low iron can make the first days feel heavy, and some people notice their lowest mood on day 1 or 2 rather than before. Read more on mood during your period and being tired on your period.

Low day, or low pattern?

One flat day on your period is normal. If it happens every cycle on the same days, that's a pattern worth knowing about. Lulu's daily check-in shows which days you usually feel lowest, so you can plan softer ones.

How to look after yourself in the menstrual phase

Pain relief that works

Heat on your belly or back, gentle movement and anti-inflammatory painkillers like ibuprofen or naproxen are first-line options. Anti-inflammatories work best if you start them at the first sign of your period, because they block prostaglandins. Check with a pharmacist if you have asthma, stomach problems or take other medicines.

Movement, if you feel like it

You don't have to skip exercise. A Cochrane review found that regular exercise (about 45 to 60 minutes, three times a week, across the month) may reduce period pain by a clinically meaningful amount. On the day itself, walking, yoga or stretching are often easiest. See exercise during your period.

Food that helps

Regular meals, water, and iron-rich foods (beans, lentils, leafy greens, red meat or fish) with vitamin C help replace what you lose. Ginger and omega-3 fats have some trial evidence for easing cramps. Full guide: what to eat on your period.

Sleep and rest

Cramps, night sweats and worry about leaks can break sleep. A warm shower, a heat pack, period underwear or an overnight pad, and lying on your side with knees bent can help. More in sleep during your period.

Other things that change on your period

See also: libido during your period and skin during your period.

The menstrual phase on hormonal contraception

If you take a combined pill, use the patch or ring, or have a hormonal IUD or implant, the bleed you get is usually not a true menstrual phase. Most of these methods stop or reduce ovulation, so there's no corpus luteum and no natural drop in progesterone. The bleed on a pill-free week is a withdrawal bleed, caused by stopping the hormones in the pill. It's often lighter and less painful. Some people bleed irregularly or not at all on hormonal methods, which is usually expected but worth checking with whoever prescribed it if it bothers you.

A quick plan for your next period

1. Know it's coming. Check your predicted start date a few days ahead, and keep pads, tampons, a cup or period underwear where you'll need them.
2. Lighten day 1 and 2 if you can. Move the hardest meeting, run or social plan a couple of days later if your pattern says those days are tough.
3. Start pain relief early. If you use ibuprofen or naproxen, taking it as bleeding starts usually works better than waiting for the pain to peak.
4. Eat and drink regularly. Skipped meals and dehydration make tiredness and headaches worse.
5. Note how you feel. One line or one tap a day. Over a few cycles you'll know which days need the most kindness.

What's normal and what isn't

Normal periods vary a lot. Small clots, a flow that's heavier on days 1 and 2, and brown blood at the end are all common. Periods that stop you doing everyday things, or that change suddenly from your usual pattern, are worth checking.