Heavy periods

Heavy periods (also known as menorrhagia) are defined as prolonged or excessive menstrual bleeding which can be painful. They can affect your quality of life and be a sign of an underlying medical condition that can be treated.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2023


Heavy periods are the most common reason for women to visit a gynaecologist and can have a significant effect on their quality of life. 

There is not always a cause but in some cases, heavy periods can be due to an underlying medical condition, such as endometriosis or fibroids. It is therefore important to see your GP.

Symptoms of heavy periods include:

  • Blood clots
  • Feeling tired during your period — this is caused by iron deficiency (anaemia)
  • Flooding the sheets at night time, needing to replace your sanitary protection every couple of hours or needing to use more than one type of sanitary product at the same time
  • Period cramps
  • Periods that last more than seven days
  • Symptoms continuing for several monthly cycles

Heavy periods can be managed in different ways to improve your quality of life.

What is a heavy period?

It is hard to define exactly what a heavy period is as what is heavy for one woman may be normal for another woman. Also, some women who think they have heavy periods may have an average amount of blood loss, while others who think they have normal periods may have a high amount of blood loss. 

Most women lose 16 teaspoons of blood (80ml) or less during a period. The average amount of blood loss during a period is six to eight teaspoons. Heavy periods are therefore defined as blood loss greater than 80ml per period and/or having periods that last longer than seven days. 

You will not usually need to measure your blood loss. Most women can tell when they are bleeding more than normal. Signs that your periods are heavy include:

  • Bleeding through your clothes or bedding
  • Having to change your normal lifestyle due to heavy bleeding
  • Needing to change your sanitary products every hour or two
  • Needing to use two types of sanitary products at the same time eg a tampon and a pad
  • Passing blood clots larger than 2.5cm — this is about the size of a 10p coin

Heavy periods every month can happen with or without other symptoms. 

Causes of heavy periods

In about half of cases, there is no underlying cause. Heavy periods are often associated with menopause, but other conditions that cause them include:

  • Adenomyosis — the lining of your womb grows through the walls of your womb
  • Endometriosis — the lining of your womb starts to grow in other places, such as your fallopian tubes
  • Non-cancerous growths — this includes
    • Endometrial polyps — non-cancerous growths in the lining of your womb or the neck of your womb (cervix)
    • Fibroids — non-cancerous growths in the muscle in and around your womb
  • Pelvic infections — these can be treated with antibiotics and include:
    • Pelvic inflammatory disease — infection of the womb, fallopian tubes or ovaries
    • Sexually transmitted infections (STIs) such as chlamydia 
  • Polycystic ovary syndrome
  • Underactive thyroid gland (known as hypothyroidism)

Diabetes can also cause heavy periods and in rare cases, it could also be:

  • Cancer of the womb
  • Von Willebrand disease — this is a blood clotting disorder, which includes other symptoms such as bleeding from other parts of your body and bruising easily

Certain medical treatments that can also cause heavy periods include:

  • Anticoagulants (blood thinners) eg warfarin
  • Herbal supplements, such as ginseng, ginkgo and soya
  • Intrauterine contraceptive device (the coil) — while the coil can cause heavy bleeding another type of intrauterine contraceptive device called the levonorgestrel intrauterine system (LNG-IUS), which releases hormones, can treat heavy periods 
  • Some types of chemotherapy

If you stop taking the oral contraceptive pill, you may also notice that your periods get heavier. This is because while on the pill, your periods are lighter and after stopping the pill they return to normal, which will be heavier than what you are used to but is not actually excessively heavy. 

You may notice a change in your periods at any time.

If there is no underlying cause for your heavy periods, you will be diagnosed with dysfunctional uterine bleeding or idiopathic menorrhagia. To be diagnosed with this condition, you will have: 

  • A normal womb and ovaries 
  • No hormonal problems 
  • Normal ovulation 
  • Regular periods

Idiopathic menorrhagia is more common in the first few years after starting your periods and in the months before the menopause. If you are a teenager with idiopathic menorrhagia, your periods may become lighter over the next few years. 

Even without an underlying cause, your doctor can still offer treatments to alleviate your symptoms of heavy periods. 

Talk to your doctor if you’re concerned about symptoms

Book an appointment with a Spire GP today

Getting a diagnosis for heavy periods

See your GP if:

  • Heavy bleeding is causing you problems
  • You have other symptoms eg bleeding between periods or period pain 
  • Your periods have become heavier
  • You're worried about your bleeding

Your GP will ask you about:

  • The effect on your everyday life
  • The type of contraception you are using
  • When you last had a cervical screening
  • Whether you plan to have a baby in the future
  • Your medical history and your family medical history — this will include any other conditions, treatments or medications that might affect your periods, as well as any blood clotting disorders that run in your family
  • Your periods — this includes duration, how often you need to change sanitary products, pain levels, whether you bleed in between periods and if they are irregular

With your consent, your doctor will perform a pelvic examination to look for:

  • Pain or tenderness
  • Signs of an underlying condition, such as endometriosis or fibroids 

You should be offered the choice of having a female doctor carry out your pelvic examination, and should be explained why the examination is needed and what it involves. Ask your doctor about anything you are unsure about. 

The pelvic examination involves: 

  • Gently pressing on your tummy to feel for abnormalities
  • Inserting an instrument called a speculum into your vagina to look at your cervix
  • Using a gloved finger to feel inside your vagina to check if your womb or ovaries are enlarged or tender 

They may also conduct a full blood test to see if you're suffering from anaemia (iron deficiency). Heavy bleeding every month means that your body needs to make more blood to replace what is being lost. Iron is needed to make blood cells and if you do not get enough iron in your diet, heavy periods can cause anaemia, with symptoms including tiredness. Two-thirds of women with heavy periods develop anaemia. 

In some cases, your doctor may conduct a blood test to detect blood clotting disorders. 

Other tests to diagnose the cause of heavy bleeding are:

  • A hysteroscopy — a thin, flexible telescope with a light and a camera at the end is inserted into the womb via your vagina to look inside your womb for fibroids or polyps; sometimes a biopsy is carried out at the same time, which involves removing a small sample of your womb lining to examine under a microscope
  • An endometrial biopsy to remove a small section of the womb lining to examine under a microscope
  • An ultrasound scan of your womb — this can be done from outside your body (pelvic ultrasound) or from inside your vagina (transvaginal ultrasound); for a transvaginal ultrasound, a small probe is inserted into your vagina to get a close image of your womb
  • Internal swabs — if your doctor suspects you have an infection, a swab (a small ball of cotton wool at the end of a stick) will be gently rubbed in different places eg the top of your vagina and your cervix, to get samples of your cells, discharge or mucus

Keeping a menstrual diary

It may be helpful to keep a menstrual diary for several months before and after any treatment for heavy bleeding. Your doctor may give you a blood loss chart to fill in, where you record how many sanitary pads and/or tampons you used each day and how many days you bled for.

A menstrual diary can help your doctor determine: 

  • The severity of your symptoms and whether you need treatment
  • Whether treatment is helping — some treatments take several months to become effective

Treatments for heavy periods

Heavy periods can be treated in many ways, depending on the underlying cause. However, not all treatments may be appropriate for you. Your doctor will recommend treatments depending on:

  • The underlying cause of your heavy periods (if you have an underlying cause)
  • Whether you are trying to get pregnant or want to get pregnant in the future
  • Your general health
  • Your personal preferences
  • Your symptoms

If there is no serious underlying cause for your heavy periods and they are not affecting your normal lifestyle much, you may choose not to have any treatment. Your doctor may recommend occasional blood tests to check for anaemia and/or iron tablets to prevent anaemia.

Non-surgical treatments

  • Combined oral contraceptive pill to stop your ovaries releasing an egg every month — this is a contraceptive and will regulate your menstrual cycle and reduce period pain, however side effects include: 
    • Breast tenderness
    • Feeling nauseous
    • Headaches
    • Mood changes
  • Cyclical progestogens — this is only prescribed if other treatments do not work and is not an effective contraceptive; it is taken as a tablet and side effects include:
    • Bleeding in between your periods
    • Breast tenderness
  • LNG-IUS — an intrauterine system in the form of a small plastic device that is inserted into your womb by a doctor or nurse and slowly releases a hormone called progestogen to prevent your womb lining growing too quickly; this system is usually the first treatment for women with heavy bleeding and doesn't affect your ability to get pregnant after you stop using it, however, it takes at least six periods before your periods will get lighter and side effects include: 
    • Acne
    • Breast tenderness
    • Irregular bleeding for six months or more
    • Missed or stopped periods
  • Non-steroidal anti-inflammatories (NSAIDs) eg ibuprofen, mefenamic acid and naproxen, to reduce your body's prostaglandin production, which is linked to heavy periods, and to relieve period pain; this may be prescribed if an IUS is not suitable or if you're waiting for further tests or treatment; it is taken as a tablet just before or when your period starts until your heavy bleeding stops; it is not a contraceptive and can be taken for as long as you need if you do not experience side effects and they are effective in making your periods lighter
  • Tranexamic acid tablets to control bleeding by helping blood clotting — this may be prescribed if an IUS is not suitable or if you're waiting for further tests or treatment, and will not affect your ability to get pregnant as it is not a contraceptive; it is sometimes prescribed with an NSAID and is taken three times a day as soon as your period starts for a maximum of four days, with side effects including: 

Your doctor may also prescribe iron tablets if you have anaemia, or recommend a diet rich in iron.

Surgical treatments

  • Endometrial ablation — a day case procedure to destroy, remove or thin the lining of the womb, which will prevent you from getting pregnant; it may not work on the first treatment so you will be offered repeat treatment to lighten or stop your periods; after your treatment, you should use sanitary pads instead of tampons; you may have stomach cramps and vaginal bleeding for a few days post-treatment, with some women experiencing prolonged pain; this procedure can be performed using: 
    • Heat — heat is applied via the vagina and cervix to destroy the womb lining and is generated using an electrical source, radio waves or lasers 
    • Ultrasound energy — high levels of ultrasound energy applied from outside the body to destroy fibroids without affecting the healthy womb lining
  • Hysterectomy — removing your womb, which will stop your periods and your ability to get pregnant; it should only be considered after all other treatment options and is a longer procedure with a longer recovery time than other surgeries to treat heavy periods
  • Myomectomy — removing the fibroids from inside your womb, which are causing your heavy periods 
  • Uterine artery embolism — shrinking fibroids that are causing your heavy periods using a small tube inserted into the large blood vessel in your thigh and then injecting small particles that block the blood vessels supplying the fibroids

Your doctor will decide which treatment is best considering your overall health and your preferences.

Emergency treatment for heavy periods

If you have very heavy bleeding during a period, your doctor may recommend an emergency treatment, which involves taking norethisterone tablets. This is a progestogen medicine. Progestogens act like your body's natural progesterone hormones to prevent your womb lining growing too quickly. 

Your doctor will recommend you take the tablets three times a day for 10 days. Heavy bleeding will usually stop in 24–48 hours after taking the tablets. If your bleeding is exceptionally heavy, your doctor may increase the dosage of your tablets and later reduce the dosage back down after your bleeding has stopped. 

Frequently asked questions

How heavy is too heavy for a period?

This can vary from one woman to the next. What is heavy for you could be normal for another woman. You may also think you have heavy periods but actually experience average blood loss.

Most women lose 16 teaspoons of blood (80ml) or less during a period. The average amount of blood loss during a period is six to eight teaspoons. Heavy periods are therefore defined as blood loss greater than 80ml per period and/or having periods that last longer than seven days.

Why is my period so heavy all of a sudden?

Sudden heavy periods may be due to natural changes in your hormones. However, they could also be due to using an intrauterine contraceptive device or stopping taking the oral contraceptive pill. Underlying medical conditions, such as endometriosis or fibroids, can also cause heavy periods. You should therefore see your GP to find out what has caused the sudden increase in blood loss during your periods. 

What do large blood clots during period mean?

Heavy periods increase your chances of passing large blood clots during your periods. If these clots are larger than 2.5cm (about the size of a 10p coin), you may have an underlying medical condition, such as adenomyosis, endometriosis, fibroids or, in rare cases, womb cancer. It is therefore important to see your GP.

Do periods get heavier as you age?

Periods usually becomes lighter after the first few years from when you started getting your periods. However, they can become heavier in the months before the menopause. 

Does a heavy period mean you are more fertile?

No, heavier periods do not mean you are more fertile. In half of cases, heavier periods are due to an underlying medical condition, which can be treated.

When should I be concerned about a heavy period?

You should see your GP if you are worried about your bleeding or: 

  • You have other symptoms eg bleeding between periods or period pain 
  • Your heavy periods are interfering with your normal lifestyle or causing you problems
  • Your periods have become heavier than usual