At a glance
- Your period might be ‘heavy’ if you lose so much blood that it impacts your daily life. For example, if you cancel plans during your period because it’s too stressful or hard to manage.
- Losing lots of blood during your period can cause your iron levels to drop, making you feel dizzy and tired.
- There are different types of medicine that can make your periods lighter, like non-hormonal medicines (such as anti-inflammatories and tranexamic acid – a medicine that reduces bleeding) and hormonal medicines (such as the pill).
- If heavy periods are affecting your life and make you feel tired or dizzy, you should speak to a doctor about treatments.
What is a heavy period?
It’s hard to explain how much bleeding counts as a ‘heavy’ period, because everyone’s menstrual cycle is different. Most experts agree that the best way to
define a heavy period is when you lose so much blood that it impacts your daily life. For example, if you cancel plans during your period because it’s too hard to manage, or you bleed so much that you have to get up in the middle of the night to change
your pad.
Doctors sometimes call heavy periods ‘heavy menstrual bleeding.’
How do I know if my periods are heavier than they should be?
Your periods might be too heavy if you:
- have to change your period product every one to two hours
- soak through period products during the night, or have to get up to change them
- pass blood clots (thick clumps of blood) bigger than 3cm – around the size of a 50c coin
- need to double-up on period products to stop leakage, like using a tampon and a pad at the same time, or period underwear and a pad.
Losing lots of blood during your period can make your iron levels drop. Iron is an important part of a special protein that carries oxygen around your body.
If you have heavy periods and low iron, you might also:
- Feel tired, dizzy, faint, or breathless
- Have low energy
- Look pale.
What could my heavy periods mean?
There are many reasons why you might have heavy periods. The most common in teens and young people are:
- Ovaries and hormones
- Your periods might be heavier if your reproductive system is still maturing. It’s common for your ovaries to be a bit disorganised for the first few years after your periods first start.
- The ovaries are small organs that release eggs and produce the hormones oestrestrogen and progesterone. Oestrogen makes the uterus lining grow and progesterone helps to organise and thin it.
- Stress
- Your periods might be heavier when you are stressed because stress changes your hormone levels.
- Nutrition and exercise
- Your diet and activity level can both impact your hormones, so they might also affect how heavy your period is. A balanced diet, regular physical activity, and a healthy body weight should help to keep your periods more regular.
Could a medical condition be causing my heavy periods?
It’s best to speak with your regular doctor (‘general practitioner’ or GP) if you are worried a medical condition is causing your heavy periods. They might ask you questions about your symptoms, as well as whether you tend to bruise easily or get lots of blood
noses. These can be signs of a bleeding disorder.
Most research into heavy periods is about adults, not young people. That’s why, when you search online for heavy periods, the information you find might not relate to your body.
Some things that might affect the heaviness of periods in teens and young people are:
- Mild bleeding disorders
- Losing or gaining weight
- Doing lots of exercise without enough nutrients in your diet
- Feeling stressed at home or about school
- Medicine like blood thinners.
When should I get help for heavy periods?
It’s a good idea to get help for heavy periods if they start impacting your life. For example, if you:
- organise your life around your period
- cancel plans or avoid activities during your period
- can’t sleep properly because you have to get up to change your period products
- have signs and symptoms of low iron that stop you from doing normal activities – for example, feeling dizzy and not being able to play sports
- worry you might have a medical condition that’s causing your heavy periods
- are upset about how much blood you are losing.
Where can I get help for heavy periods?
If you haven’t told your parents about your heavy periods, it’s usually best to start by speaking with them or another trusted adult. This way, they will be able to support you.
Your GP is the best person to give you medical advice about heavy periods. They will ask you questions about your periods, so it’s a good idea to make a note of things like:
- How often you need to change your period products
- Whether you get blood clots bigger than 3cm
- Any other symptoms they have.
If your GP thinks you could have low iron, they might order some blood tests. They might want to do extra tests to look for an underlying bleeding problem if your iron levels are very, very low.
Treatments for heavy periods
If you need treatment for your heavy periods, there is a good chance a doctor will suggest you take some kind of medicine.
The different types of medicine that can make your periods lighter are:
- Non-hormonal medicines
- Over-the-counter anti-inflammatory pain medicines like ibuprofen, mefenamic acid, and naproxen can all help to reduce blood flow to the uterus lining. They can also ease period pain.
- Tranexamic acid is a prescription medicine that stops your body from breaking down blood clots too quickly. It does not cause clots.
- Hormonal medicines
- Hormonal contraception like the pill or intrauterine devices (IUDs) can reduce your bleeding.
- You can also use the pill to skip (purposely miss) your period.
- There are lots of contraceptive pills with different hormones, so if one doesn’t work, you can try another.
Things you might be wondering
How long does an average period last for?
Most periods last between two and seven days. But some people have longer periods, and others have shorter ones. If your period usually lasts longer than eight days and affects your daily life, it’s best to speak with a doctor.
What tests will my doctor do for my heavy periods?
If you have heavy periods, your GP will usually ask you about your symptoms. They might order some blood tests to check your iron levels and look for other things in your blood, like proteins that help to stop any bleeding.
Pelvic exams or ultrasounds are rarely necessary to investigate heavy periods.
I lose lot of blood during my period. Should I be worried?
No two periods are the same. If you feel like you lose lots of blood, you can always speak to your GP to make sure your iron levels are healthy and there is nothing else going on.
How do I know if I’m iron deficient?
If you feel tired or dizzy, have low energy, or look pale, you might have low iron. The only way to know for sure is with a blood test. Speak to your GP for advice.
Helpful links
Developed by The Royal Children’s Hospital (RCH); medical review by the Gynaecology department, with input from the Kids and Teens Pelvic Pain Clinical Network team. Created with advice from the RCH Health Literacy Youth Advisory Committee.
Reviewed August 2026
Speak with a doctor for up-to-date and personalised medical advice.