Heavy Periods: Causes, Signs and When to Get Help

Heavy periods, medically called menorrhagia, are periods with heavy or prolonged bleeding that interfere with daily life. You may need to change a pad or tampon every hour or two, pass large clots, bleed through clothes or bedding, or feel tired and short of breath. Treatment can help, so discuss heavy bleeding with a GP.

What counts as a heavy period?

Periods vary a great deal from person to person, so “heavy” is less about an exact amount of blood and more about the effect on your life. The NHS says you may have heavy periods if you need to change your pad or tampon every 1 to 2 hours, need to use two types of period product together, have periods lasting more than 7 days, pass blood clots larger than about 2.5cm (the size of a 10p coin), bleed through to your clothes or bedding, avoid daily activities or take time off work because of your periods, or feel tired or short of breath a lot.

It can be normal to have heavy periods at certain times, such as when you first start having periods, after pregnancy or when approaching menopause. Heavy bleeding that is new, worsening or combined with other symptoms still deserves a check, because several treatable conditions can cause it.

What causes heavy periods?

In many cases no single cause is found, but the Mayo Clinic and the NHS list several common causes:

• Hormone imbalance: when oestrogen and progesterone are out of balance, the lining of the womb can become too thick and shed heavily. Conditions such as polycystic ovary syndrome, thyroid problems, obesity and insulin resistance can contribute.
• Problems with ovulation: if an ovary does not release an egg in a cycle, the body may not make progesterone as usual, which can lead to heavy or unexpected bleeding.
• Fibroids and polyps: fibroids are non-cancerous growths in the muscle of the womb, and polyps are small growths on its lining. Both can cause heavy or prolonged bleeding.
• Adenomyosis and endometriosis: in adenomyosis, tissue from the lining of the womb grows into the wall of the womb, causing heavy and often painful periods.
• Bleeding disorders: conditions that make you bleed more easily, such as Von Willebrand disease, can cause heavy periods.
• Medicines and devices: some anticoagulant medicines, chemotherapy medicines and a hormone-free intrauterine device (IUD) can increase bleeding.
• Other conditions: pelvic inflammatory disease, liver, kidney or thyroid disease, and rarely womb cancer, can also be involved.

Can heavy periods cause anaemia?

Yes. Losing a lot of blood month after month can deplete iron stores and lead to iron deficiency anaemia, in which the blood does not have enough healthy red blood cells to carry oxygen around the body. The NHS notes that you may have blood tests to check for underlying conditions such as iron deficiency anaemia. Feeling unusually tired, dizzy, pale or short of breath alongside heavy periods is a good reason to see a GP. Talk to a doctor or pharmacist before taking iron supplements or any other product for anaemia.

What treatments are available?

Heavy periods do not always need treatment, but several options can help if they are affecting your daily life. The NHS lists GP treatments including some types of contraception, such as an intrauterine system (IUS) or the combined contraceptive pill, medicine to help reduce bleeding such as tranexamic acid, and prescription-only anti-inflammatory painkillers such as mefenamic acid or naproxen.

If those treatments do not work, or a GP thinks a condition may be causing your heavy periods, you will usually be referred for tests or to see a specialist. Specialist treatments include removing the lining of the womb (endometrial ablation), removing fibroids, and total or partial removal of the womb (hysterectomy). NICE stresses that treatment decisions should be made together, taking account of what matters most to you, including whether you want to be able to get pregnant in future, since some treatments affect fertility.

How common are heavy periods?

Heavy periods are a frequent reason for seeking help. NICE states that about 1 in 20 women aged between 30 and 49 years see their GP each year for help with heavy periods or menstrual problems. That figure is a reminder that heavy bleeding is a recognised medical issue, not something to simply put up with, and that GPs hear about it often.

Tracking your periods before your appointment

A short record can make a GP appointment more useful. Before you go, note how often you change period products, whether you bleed through at night, the size of any clots, how many days bleeding lasts, any bleeding between periods or after sex, and any pain, tiredness or breathlessness. Bring a list of medicines you take, including anticoagulants, and mention any family history of bleeding disorders.

When to see a doctor

See a GP if heavy periods are affecting your life, you have had heavy periods for some time, you have severe pain during your periods, you bleed between periods or after sex, or you have heavy periods with other symptoms such as pain when peeing, pooing or having sex, as advised by the NHS. Seek urgent medical help for very heavy bleeding that soaks through a pad or tampon every hour for several hours, large clots with severe pain, fainting, or bleeding after menopause.

In an emergency call 911 (US), 999 (UK) or 112 (EU).