A period is the part of the menstrual cycle when you bleed from your vagina for a few days.
For most women, this happens every 28 days or so. But it's common for periods to be more or less frequent than this, ranging from day 21 to day 40 of their menstrual cycle.
Your period can last from 2 to 7 days. But it will usually last for about 5 days. The bleeding is often 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, brown or black.
You'll lose about 30 to 72ml (5 to 12 teaspoons) of blood during your period. But you can bleed more heavily than this.
Start of periods
Periods usually start at about the age of 12. Some girls will start them earlier or later.
A delay in starting periods is not usually a cause for concern. Most girls will be having regular periods by age 16 to 18.
Sanitary products soak up or collect the blood released during your period.
The main types of sanitary products are:
- sanitary pads
- menstrual cups
Sanitary 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. You can use them on days when your period is very light.
Tampons are small tubes of cotton wool that you insert into your vagina. They soak up the blood before it comes out of your body.
There are 2 types of tampons - tampons with an applicator and tampons without an applicator. You use your fingers to insert the tampons without an applicator. In both types, 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 feel it inside you. If you can feel it or it hurts, it might not be in properly.
A tampon cannot get stuck or lost inside you. Your vagina holds it in place and it expands inside you as it soaks up the blood.
Menstrual cups are an alternative to sanitary pads and tampons. The cup is made from silicone (a rubber-like material) and you put it inside your vagina.
Menstrual cups collect the blood rather than absorb it. You throw away sanitary pads and tampons after use. But you can wash menstrual cups and use them again.
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
These symptoms usually improve when your period starts and disappear a few days afterwards. Not all women who have periods get PMS.
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 work by preventing ovulation. For example, the contraceptive pill, contraceptive patch and contraceptive injection.
Read more about contraception
Read more about getting pregnant
Changes in your periods
Your periods can change. For example, they may last longer or get lighter. This does not mean there's a problem, but you need to any changes checked.
You should see your GP if you have bleeding:
- between periods
- after having sex
- after the menopause
The changes could be caused by an infection or abnormalities in the cervix (the neck of the womb). In rare cases, it could be cancer.
You could be pregnant if you miss a period and you've had sex. You should take a pregnancy test. You can take a home pregnancy test or attend your GP for this if you prefer. Even if you are definitely not pregnant and you've missed 3 periods in a row, you should contact your GP.
They will investigate the cause and recommend any necessary treatment.
Read more about stopped or missed periods
Read more about cervical screening
Your periods will continue until you reach the menopause. This usually happens when you are in your late 40s to mid-50s. In Ireland, the average age of menopause is between 50 and 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.
Content supplied by the NHS and adapted for Ireland by the HSE