Short answer: NHS signs include changing a pad or tampon every one to two hours, emptying a cup more often than recommended, using two products together, bleeding longer than seven days, clots larger than about 2.5 cm, leaks, avoided activities, tiredness or shortness of breath.

Why millilitres are not the starting point

Most people cannot measure menstrual blood accurately at home. NICE therefore tells clinicians to recognise the major effect heavy menstrual bleeding can have on quality of life and to aim treatment at improving that impact rather than focusing only on blood loss.

A practical log uses events that can be observed consistently: how often protection changes, how many bleeding days occur, whether protection leaks, and whether the period changes daily plans.

What to record

Use neutral notes rather than trying to label the cause. A heavy pattern can have many explanations, and the same visible amount may affect two people differently.

  • How often a pad, tampon, cup or period underwear needs changing.
  • Whether two products are needed together.
  • Total bleeding days.
  • Approximate clot size and frequency.
  • Leaks onto clothes or bedding.
  • Activities, work or school missed.
  • Tiredness or shortness of breath that occurs with the pattern.

When to arrange assessment

The NHS advises seeing a GP when heavy periods affect life, have continued for some time, involve severe pain, occur with bleeding between periods or after sex, or appear with pain when peeing, pooing or having sex.

NICE recommends that a clinical history cover the nature of bleeding, related symptoms and quality-of-life impact. It also recommends a full blood count for people assessed with heavy menstrual bleeding.

Do not wait for every cycle to meet every sign on the list. A persistent change from your baseline, especially one that affects normal activities or comes with tiredness or breathlessness, is enough reason to describe the pattern and ask for assessment.

  1. Bring a short cycle log rather than relying on memory.
  2. Mention medicines or devices that may affect bleeding.
  3. Use local urgent care if you feel acutely unwell rather than relying on this checklist.
Important: These signs describe a pattern; they do not diagnose its cause. Acute illness, fainting, chest pain or severe breathing difficulty needs urgent local assessment.

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