Menstrual Phase: What's Happening and What Helps

The menstrual phase is the first phase of your cycle, and it is your period. If you did not get pregnant, estrogen and progesterone drop, and the thickened lining of your uterus is shed through the vagina as bleeding. It usually lasts about 5 days, though anything from 2 to 7 days is considered normal.

Quick summary: Day 1 of your period is day 1 of your cycle. Bleeding usually lasts 2 to 7 days and is often heaviest at the start. Cramps, tiredness and mood dips are common but not universal. Heat, rest, gentle movement and over-the-counter pain relief can help, and severe pain or very heavy bleeding is worth checking with a doctor.

What is happening in your body

Each cycle, your body builds up the lining of the uterus in case of pregnancy. When there is no pregnancy, hormone levels fall and the lining is shed. That shedding is your period.

The first day of bleeding is counted as day 1 of your menstrual cycle. This phase overlaps with the start of the follicular phase, because the ovaries are already getting ready to grow follicles for the next cycle. For the full picture, see the 4 phases of the menstrual cycle explained.

What's typical

• Length: About 5 days is usual, with a range of 2 to 7 days (NHS). Cleveland Clinic notes bleeding often lasts 3 to 7 days.
• Flow: Often heaviest in the first 2 days, then lighter.
• Amount: Around 2 to 3 tablespoons in total, according to Cleveland Clinic and the Office on Women's Health. It can look like a lot more than that.
• Color: Red when flow is heavier, and pink or brown when lighter (NHS).

Everyone's period is a little different, and yours can change from month to month. If you are curious about how your cycle length fits in, see how long is a normal menstrual cycle.

How you might feel

Many people notice some of these during their period, though plenty of people feel mostly normal:

• Cramps in the lower belly or back
• Tiredness
• Headaches
• Bloating or tender breasts
• A lower mood or feeling more emotional

These are tendencies, not guarantees. How you feel can vary from one cycle to the next.

What can help

For cramps and period pain, the NHS suggests:

• A heat pad or hot water bottle, wrapped in a tea towel, on your tummy
• A warm bath or shower
• Massaging your tummy and back
• Gentle exercise, such as yoga, walking, swimming or cycling
• Painkillers such as ibuprofen or paracetamol (follow the label, and ask a pharmacist or doctor if you are unsure)

For low energy, there are not any magic fixes, but rest, regular meals, fluids and a decent night's sleep are reasonable places to start. If you notice you tend to feel flat on day one or two, you can plan for that, such as keeping that evening free.

What about food and workouts? You may see advice to eat or train in a specific way during your period. The research on this is limited and early. A 2023 review from McMaster University found little evidence behind phase-specific diet and exercise rules. If gentle movement feels good, great. If rest feels better, that is fine too.

Pads, tampons and cups: a quick safety note

The Office on Women's Health advises wearing a tampon for no more than 8 hours. If you ever feel sick after using a tampon, seek medical advice. Whatever product you use, change it regularly and choose what feels comfortable for you.

Small things that make a period easier

• Keep supplies in your bag so you are never caught off guard.
• Wear comfy clothes and keep a heat pack or hot water bottle handy.
• If you know your first days tend to be rough, go easy on your schedule where you can.
• Tell someone you trust what helps, whether that is a friend, family member or partner.

When to see a doctor

Talk to a doctor or nurse if:

• Your pain is severe, or it stops you doing your usual activities
• You are soaking through a pad or tampon every 1 to 2 hours
• Your period lasts longer than 7 days
• You pass clots larger than a quarter
• You bleed between periods
• Your periods suddenly become much heavier, lighter or more painful than usual
• You have not had a period for 3 months or more and you are not pregnant

The NHS advises getting urgent help (an urgent GP appointment or NHS 111 in the UK) if pelvic or period pain is severe or worse than usual and painkillers are not helping.

Period pain that interferes with life is common, but it is not something you simply have to put up with. Doctors can look for causes and discuss treatment.

Keeping an eye on patterns

It helps to note the first day of each period, how heavy the flow is and how long it lasts. Over a few months you will see your own usual pattern, which makes any change easier to spot and easier to explain to a doctor. See how to track your period and cycle for tips.

Where Mochi Moon fits

In Mochi Moon, an iPhone app launching in fall 2026, you can log your period, flow, symptoms, moods, energy and sleep. If you choose to share with a partner, they can see your current phase in plain language and what tends to help, only what you decide to share.