Bleeding · For ages 13–17
How can I tell whether my period bleeding is heavy?
It can be difficult to know how much bleeding counts as heavy. Often it is easier to look at how the bleeding affects everyday life.
What happens?
Heavy bleeding can make everyday life difficult
Heavy menstrual bleeding means losing more blood than usual during your period. You do not need to measure the amount.
Signs include needing to change pads or tampons very frequently, using several products together to avoid leaks, changing during the night, bleeding through clothes or bedding, or passing blood clots. Heavy bleeding may also make you feel tired because it can deplete your iron stores.
Periods can be irregular during the first few years. You do not need to wait for them to become regular before seeking help with heavy bleeding. A doctor can investigate the cause, consider blood tests and find suitable treatment.
Learn more
Which describes what you have noticed?
Choose the option that fits best to see guidance on what you can do next.
Bleeding through can be a sign of heavy menstrual bleeding, particularly when it happens often. Tell a doctor or school nurse about it.
A single leak may be due to product placement or a full product. Repeated leaking despite appropriate protection tells you more about blood loss.
Explain how often it happens and whether you must leave lessons or wake during the night. You can receive advice about products while the cause, possible iron deficiency and bleeding treatment are assessed.
If a large pad becomes fully soaked in one or two hours several times in a row, contact a doctor that day. Call 116 117 if your GP is unavailable and it cannot wait. You can ask an adult for help.
Separating changes because the product is completely full from changes because you want to feel dry makes bleeding easier to describe. Look out for dizziness, weakness or feeling unwell.
Notes or other records must never delay help when you are bleeding heavily right now. A trusted adult can help you get in touch.
Heavy bleeding may lead to iron deficiency or anaemia. A doctor can consider whether blood tests are needed.
Blood loss can deplete your iron stores, and some people develop low haemoglobin. Iron is important for transporting oxygen in your blood, although tiredness has many possible causes.
Explain both the amount of bleeding and your energy levels. Assessment may include blood tests and treatment of the bleeding itself. Iron supplements alone do not stop heavy menstrual bleeding.
You do not have to be sure. If bleeding worries you or affects daily life, you can have it assessed.
Think about daily life rather than trying to calculate millilitres: Do you need to change products at night, use double protection or skip activities? These are useful things to mention.
You do not need evidence or comparisons with friends. Describe what you notice and ask for help assessing whether bleeding and other symptoms require follow-up.
What can you do now?
Describe how often you change products, whether you bleed through, how long bleeding lasts and whether you feel unusually tired. Make a doctor's appointment if this happens frequently or limits your daily life. If you are bleeding heavily right now, follow the advice under 'When bleeding needs urgent attention'.
Find the words you need
Create a short message you can say, show or send to someone you trust, a school nurse or a doctor.
Help me explainSources
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The text and guidance were checked against sources on 3 October 2026.