Overview
A period is the part of the menstrual cycle when a woman bleeds from her vagina for a few days.
For most women this happens around every 28 days, but it's common for periods to be more or less frequent than this, ranging from every 21 days to every 35 days.
Your period can last between 2 and 7 days, but it will usually last for about 5 days. The bleeding tends to be heaviest in the first 2 days.
When your period is at its heaviest, the blood will be red. On lighter days, it may be pink or brown.
You'll lose about 20 to 90ml (about 1 to 5 tablespoons) of blood during your period, although some women bleed more heavily than this.
Read more about heavy periods, period pain, irregular periods and stopped or missed periods.
When do periods start?
Periods usually begin at around the age of 12, although some girls will start them earlier or later.
A delay in starting periods isn't usually a cause for concern. Most girls will be having regular periods by age 16 to 18.
Period products
Period products soak up or collect the blood released during your period. The main types of sanitary products are:
- pads
- tampons
- menstrual cups
Pads
Pads are strips of padding that have a sticky side you attach to your underwear to hold them in place. One side of the pad is made of an absorbent material that soaks up the blood.
Pads come in many sizes, so you can choose one to suit how heavy or light your period is.
Pantyliners are a smaller and thinner type of sanitary pad that can be used on days when your period is very light.
Tampons
Tampons are small tubes of cotton wool that you insert into your vagina to soak up the blood before it comes out of your body.
There are 2 types of tampon - ones that come with an applicator and others without an applicator that you insert with your fingers. In both cases, there's a string at one end of the tampon, which you pull to remove it.
Tampons come with instructions that explain how to use them. If the tampon is inserted correctly, you should not be able to feel it inside you. If you can feel it or it hurts, it might not be in properly.
It is not possible for a tampon to get stuck or lost inside you. Your vagina holds it firmly in place and it expands inside you as it soaks up the blood.
Menstrual cups
Menstrual cups are an alternative to sanitary pads and tampons. The cup is made from silicone and you put it inside your vagina.
Menstrual cups collect the blood rather than absorb it. Unlike sanitary pads and tampons, which are thrown away after they've been used, you can wash menstrual cups and and use them again.
Period underwear
Period underwear are pants made from absorbent fabric. They soak up blood in the same way as pads, and have a layer to prevent leaks. They're designed to be washed and reused.
PMS (premenstrual syndrome)
Changes in your body's hormone levels before your period can cause physical and emotional changes.
This is known as PMS (premenstrual syndrome) or PMT (premenstrual tension).
There are many possible symptoms of PMS, but typical symptoms include:
- feeling bloated
- breast tenderness
- mood swings
- feeling irritable
- spotty skin or greasy hair
- loss of interest in sex
- headaches
These symptoms usually improve when your period starts and disappear a few days afterwards. Not all women who have periods get PMS.
Getting pregnant
Working out when you can get pregnant – your fertile time – can be difficult. It's around the time you ovulate, which is about 12 to 14 days before the start of your next period.
But sperm can survive inside a woman's body for up to 7 days before ovulation occurs. This means your fertile time extends back earlier in your cycle.
You cannot get pregnant if you do not ovulate. Some hormonal methods of contraception, such as the contraceptive pill, contraceptive patch and contraceptive injection, work by preventing ovulation.
Changes in your periods
Your periods can change – for example, they may last longer or get lighter. This does not necessarily mean there's a problem, but it does need to be investigated.
You can see your GP, or visit your nearest women's clinic or contraceptive clinic.
Bleeding between periods, bleeding after having sex, or bleeding after the menopause needs to be checked by a doctor.
It might be caused by an infection, abnormalities in the neck of the womb (the cervix) or, in rare cases, it could be cancer.
You could be pregnant if you miss a period and you've had sex. See your GP if you've taken a pregnancy test and the result is negative (you're not pregnant) and you've missed 3 consecutive periods.
They will investigate the cause and recommend any necessary treatment.
When do periods stop?
Your periods will continue until you reach the menopause, which usually happens when you are in your late 40s to mid-50s. In the UK the average age of menopause is 51.
Your periods may start to become less frequent over a few months or years before stopping altogether. In some cases they can stop suddenly.
Delaying your period
It’s possible to delay your period if you take the combined contraceptive pill.
How you do this depends on the type of combined pill you take. Speak to a GP or pharmacist, or a doctor or nurse at a sexual health clinic, about how to delay your period using the combined pill.
If you do not take the combined pill already, you will need to start it a few weeks before the time you want to delay your period.
If you do not want to take the contraceptive pill, your GP can prescribe a medicine called norethisterone to delay your periods, but this is not suitable for everyone.
Starting your periods
Most girls start their periods when they're about 12, but they can start as early as 8, so it's important to talk to girls from an early age to make sure they're prepared.
Respond to questions or opportunities as they arise and do not be embarrassed. Periods are natural.
Talking about periods
Try to talk about periods as an ongoing process rather than a formal sit-down talk.
You can use TV ads for tampons, or buying period products at the supermarket, for example, to start the conversation about periods. Or simply ask your daughter what she already knows and go from there.
Use clear language, like "vagina". Emphasise that periods are completely normal and natural – they're part of growing up.
Boys also need to learn about periods. Talk to them in the same way as girls about the practicalities, mood changes that can come with periods, and the biological reason behind periods. It will keep them informed, as well as help them to understand about periods.
When a girl starts her periods it's a sign that her body is now able to have a baby. It's important that she also knows about getting pregnant and contraception.
The questions girls ask about periods
Here are some of the questions that you, as a parent, might get asked by girls about periods, with suggestions on how to answer them:
How will I know when my periods are going to start?
Signs that your period is on its way are if you've grown underarm and pubic hair. Typically, you'll start your periods about 2 years after your breasts start growing. The average girl will get her first period around 12 years old, but it varies from person to person.
Why have my periods not started yet?
Your periods will start when your body is ready. This is usually between age 8 and 17, or 2 years after your first signs of puberty.
Possible reasons for delayed periods include being underweight, doing lots of exercise (including dance, gymnastics and athletics), stress and a hormone imbalance.
See a GP if your periods have not started by age 15 (or 13 if you do not have any other signs of puberty). Your GP may suggest a blood test to check your hormone levels.
You may be referred to a specialist (usually a gynaecologist – a specialist in women's health) to find out what's causing your delayed periods and discuss any treatments that might help.
How do I get ready for my first period?
Talk to your parent or another adult you trust about what you can expect before it actually happens.
It's a good idea to start carrying pads or tampons around with you in advance.
If you find yourself at school without a pad or tampon, ask a teacher or the school nurse for some.
How long will my first period last?
Your first period might not last very long, as it can take your body some months to get into a regular pattern. As a general rule, once they're settled, you'll have a period every 23 to 35 days and it will last 2 to 7 days.
How much blood will I lose?
It might seem a lot, but it's only about 20 to 90ml (about 1 to 5 tablespoons). It's not a sudden gush – you'll just see a reddish-brown stain on your pants or on your sheets when you wake up in the morning.
What if period blood leaks through my clothes?
There are ways of covering up stains until you're able to change your clothes, such as tying a sweatshirt around your waist. Keep a spare pair of pants and tights at school or in your bag.
Should I use pads, tampons, menstrual cups or period underwear?
This is up to you. Tampons, menstrual cups, disposable or reusable pads (towels) and period underwear are safe and suitable if you've just started your period. You might want to use pads for your very first period as tampons and cups can take some getting used to. It might be worth experimenting until you find the product that suits you best.
Can a tampon get lost inside me?
No, it can't. When you insert a tampon, it stays in your vagina. All tampons come with a string at one end that is designed to stay outside your body. You can remove the tampon at any time using this string.
What if I forget to remove my tampon?
If you forget to remove your tampon, it can turn sideways or become compressed at the top of your vagina. This can make it difficult for you to pull it out. If you think you've left a tampon in and you can't get it out, go to your GP or nearest sexual health clinic. They can remove it for you.
Further reading for girls
Period problems
If problems with your periods are affecting your life, there's help and support available.
Before you see your GP about period problems, it can be useful to keep a diary of your symptoms throughout the menstrual cycle. This can give your doctor a detailed idea of what happens, and when, during your cycle.
Painful periods
Pain during periods is common. It's usually caused by the womb contracting to push out the blood.
Exercise may help relieve the pain, as well as taking over-the-counter painkillers, such as ibuprofen and aspirin.
However, do not don't take ibuprofen or aspirin if you have asthma or stomach, kidney or liver problems. Aspirin should not be taken by anyone under 16 years of age.
You could try paracetamol to relieve period pain, but studies have shown that it does not reduce pain as effectively as ibuprofen or aspirin.
Hormonal contraception (such as the contraceptive pill, the intrauterine system (IUS), the contraceptive patch or the contraceptive injection) can reduce period pain.
See your GP if the pain is so severe that it affects your daily life.
Read more about painful periods.
Heavy periods
Some women naturally have heavier periods than others, but if your periods are so heavy that they impact your life, there is help available.
Talk to your GP about your bleeding, including how often you have to change your sanitary protection (towels, tampons or menstrual cup).
Your GP can investigate why you're experiencing heavy bleeding. These investigations may include a physical examination, blood tests or scans.
Treatments for heavy periods can include:
- some types of hormonal contraception, such as the intrauterine system (IUS) or the contraceptive pill
- tranexamic acid tablets
- anti-inflammatory painkillers, such as ibuprofen or mefenamic acid
- progestogen tablets
- surgery (depending on the cause)
Read more about heavy periods.
Irregular periods
A period usually lasts 2 to 7 days, with the average period lasting 5 days.
The length of the menstrual cycle varies from woman to woman, but the average is to have periods every 28 days. Regular cycles that are longer or shorter than this, from 21 to 40 days, are normal.
But some women have an irregular menstrual cycle.
This is where there is a wide variation in:
- the time between your periods (they may arrive early or late)
- the amount of blood you lose (periods may be heavy or light)
- the number of days the period lasts
Irregular periods can be common during puberty and just before the menopause. Changing your method of contraception can also disturb your normal menstrual cycle.
Read more about irregular periods, including what causes them and when treatment may be necessary.
Stopped or missed periods
There are many reasons why you may miss your period, or why periods may stop altogether.
Some common reasons are:
- pregnancy
- stress
- sudden weight loss
- being overweight
- overexercising
- reaching the menopause
If your periods stop and you're concerned, see your GP.
Read more about stopped or missed periods.
PMS (premenstrual syndrome)
PMS is thought to be linked to changing levels of hormones throughout the menstrual cycle.
Not all women get PMS. If you do, the range and severity of symptoms can vary.
Symptoms may include:
- mood swings
- feeling depressed or irritable
- headaches
- tiredness
- bloating
- breast tenderness
Symptoms usually start and can intensify in the 2 weeks before your period, and then ease and disappear after your period starts.
Read more about PMS, including symptoms and treatment.
Menstrual migraine
Menstrual migraines are very painful headaches that happen around the time of your period. They usually happen around 2 days before your period starts, or during the first 3 days of your period.
They're linked to changing levels of hormones and can be more painful than other types of migraine.
Most women who get menstrual migraines also get migraines at other times.
See a GP if you get menstrual migraines. They can advise you about medicines that can help.
Find out more about menstrual migraines from the Migraine Trust
Endometriosis
Endometriosis is a condition where pieces of tissue similar to that which lines the womb (endometrium) grows outside the womb, such as in the ovaries and fallopian tubes.
Not all women have symptoms, but endometriosis can cause:
- painful, heavy or irregular periods
- pelvic pain
- pain during or after sex
- pain or discomfort when going to the toilet
- bleeding from your bottom
- feeling tired all the time
See your GP if you have symptoms of endometriosis, especially if they're having a big impact on your life.
Read more about endometriosis, including how it's diagnosed and treated.
Ovulation pain
Some women get a one-sided pain in their lower abdomen when they ovulate.
The pain can be a dull cramp or sharp and sudden. It can last just a few minutes or continue for 1 to 2 days. Some women notice a little vaginal bleeding when it happens.
Painful ovulation can usually be eased by simple remedies like soaking in a hot bath or taking an over-the-counter painkiller, such as paracetamol.
If you're in a lot of discomfort, see your GP about other treatment options.
Read more about ovulation pain.