Periods vary a lot from person to person, so "heavy" on its own is hard to judge. A few specific markers are more useful: bleeding that lasts beyond 7 days, soaking through a pad every hour or two, passing clots bigger than a coin, flooding through at night, or feeling persistently tired or breathless. Any one of these is worth getting checked rather than managed on your own.

The markers that matter more than "heavy"

  • Duration beyond 7 days — a period that keeps going well past a week
  • Soaking a pad or tampon every 1-2 hours — needing to change that frequently, especially for more than a few hours at a stretch
  • Clots bigger than a coin — larger clots suggest heavier flow than smaller spotting-type clots
  • Flooding or leaking through at night — needing to change protection overnight or waking up to leakage
  • Tiredness or breathlessness — signs the blood loss may be affecting you beyond the bleeding itself (possible anaemia)

What commonly causes it

  • Fibroids — benign growths in the uterine wall that can make periods heavier or longer
  • Polyps — small growths in the uterine lining that can cause irregular or heavy bleeding
  • Thyroid imbalance — both an underactive and overactive thyroid can disrupt cycle regularity and flow
  • Anovulatory cycles — cycles where ovulation doesn't happen can lead to unpredictable, sometimes heavy bleeding
  • Bleeding disorders — less common, but worth ruling out with a doctor if heavy bleeding has been a pattern since your periods started

What a workup usually looks like

Your doctor will typically start with your history and an examination, then may suggest a pelvic ultrasound to look at the uterus and ovaries, blood tests (including a check for anaemia and thyroid function), and sometimes further tests depending on what the ultrasound shows. The goal is to find the underlying cause rather than just manage the bleeding itself.

Clots bigger than a coin, soaking a pad every hour or two, or bleeding past 7 days aren't just a "heavy" period — they're signals worth getting checked, not symptoms to just push through.

Frequently asked

How many days of bleeding is actually too long?

Most periods last around 3-7 days. Bleeding that regularly goes well beyond 7 days is a marker worth discussing with your doctor, especially if it's a change from your usual pattern.

What size clot is a red flag?

As a rough guide, clots larger than a coin suggest heavier flow than is typical and are worth mentioning to your doctor, particularly if they're a frequent part of your cycle rather than an occasional occurrence.

Can heavy periods cause anaemia?

Yes. Significant or prolonged blood loss each cycle can lower your iron stores over time, leading to tiredness, breathlessness, or paleness. This is one reason heavy bleeding is worth investigating rather than just managing symptomatically. For more on iron levels, see low ferritin with normal haemoglobin: what it means.

Are fibroids always the cause of heavy bleeding?

No. Fibroids are one common cause, but polyps, thyroid problems, anovulatory cycles, and bleeding disorders can all cause heavy or prolonged bleeding too. An ultrasound and blood work help narrow down the actual cause rather than assuming it's fibroids. If fibroids are found, see small fibroids: monitor or surgery? for what happens next.

Is this different from just having an irregular cycle?

Yes. Irregular cycles are about timing — periods coming early, late, or unpredictably. Heavy or prolonged bleeding is about volume and duration within a cycle, and can happen even if your cycle length itself is regular. For timing-related concerns, see what causes irregular periods and when to worry.