Heavy Periods (Menorrhagia)

What is a normal period, a heavy period, and menorrhagia?

About 1 in 3 women describe their periods as being heavy. However, it is often difficult to know if your periods are normal or heavy compared with other women. Some women who feel they have heavy periods actually have an average blood loss. Some women who feel they have normal periods actually have a heavy blood loss. Most of the blood loss (about 90%) usually occurs in the first three days with either normal or heavy periods.

Some medical definitions of blood loss during a period are:

  • A normal period is a blood loss between 20 and 60 ml (4-12 teaspoonfuls). Bleeding can last up to eight days, but bleeding for five days is average.
  • A heavy period is a blood loss of 60-80 ml or more. This is about half a teacupful or more. However, it is difficult to measure the amount of blood that you lose during a period. For practical purposes, a period is probably heavy if it causes one or more of the following:
    • Flooding through to clothes or bedding.
    • You need frequent changes of sanitary towels or tampons.
    • You need double sanitary protection (tampons and towels).
    • You pass large blood clots.
  • Menorrhagia means heavy periods that recur each month. Also, that the blood loss interferes with your quality of life. For example, if it stops you doing normal activities such as going out, working or shopping. Menorrhagia can occur alone or in combination with other symptoms.


The cause is not known in most cases

This is called dysfunctional uterine bleeding and is the cause of heavy periods in four to six out of ten cases. In this condition the uterus (womb) and ovaries are normal. It is not a hormonal problem. Ovulation is often normal and the periods are usually regular. It is more common if you have recently started your periods or if you are approaching the menopause. At these times you may find your periods are irregular as well as heavy.

A chemical called prostaglandin may play a part. The amount of prostaglandin in the blood may be different in women with heavy periods. The lining of your uterus is more sensitive to the effects of prostaglandin, which results in heavier periods. In some women, the blood vessels that supply blood to the lining of the womb are dilated (larger), which then results in the blood loss being heavier. This dilatation is also thought to be due to prostaglandins in the body.

Other causes

These are less common. They include the following:

  • Fibroids. These are benign (noncancerous) growths in the muscle of the uterus. They often cause no problems, but sometimes cause symptoms such as heavy periods.
  • Other conditions of the uterus, such as endometriosis, infections or polyps, may lead to heavy periods. Cancer of the lining of the uterus (endometrial cancer) is a very rare cause. Most cases of endometrial cancer develop in women aged in their 50s or 60s.
  • Hormonal problems. Periods can be irregular and sometimes heavy if you do not ovulate every month. For example, this occurs in some women with polycystic ovary syndrome. Women with an underactive thyroid gland may have heavy periods.
  • The intrauterine contraceptive device (IUCD, or coil) sometimes causes heavy periods. However, a special hormone-releasing IUCD called the intrauterine system (IUS) can actually treat heavy periods.
  • Pelvic infections. There are different infections that can sometimes lead to heavy bleeding developing. For example, chlamydia can occasionally cause heavy bleeding. These infections can easily be treated with antibiotics.
  • Warfarin or similar medicines interfere with blood clotting. If you take one of these medicines for other conditions, it may have a side-effect of heavier periods.
  • Some drugs used for chemotherapy can also cause heavy periods.
  • Blood clotting disorders are rare causes of heavy bleeding. Other symptoms are also likely to develop, such as easy bruising or bleeding from other parts of the body.

If you stop taking the contraceptive pill it may appear to cause heavy periods. Some women become used to the light monthly bleeds that occur whilst on the pill. Normal periods return if you stop the pill. These may appear heavier, but are usually normal.

  • An internal (vaginal) examination to examine the shape and size of your uterus and cervix (neck of the womb) may be performed. However, an examination is not always necessary, especially in younger women who do not have any symptoms to suggest anything other than dysfunctional uterine bleeding.
  • A blood test to check for anaemia is usually performed. If you bleed heavily each month then you may not take in enough iron in your diet, needed to replace the blood that you lose. (Iron is needed to make blood cells.) This can lead to anaemia which can cause tiredness and other symptoms. Up to 2 in 3 women with recurring heavy periods develop anaemia.

If a vaginal examination is normal (as it is in most cases), and you are under the age of 40, no further tests are usually needed. The diagnosis is usually dysfunctional uterine bleeding and treatment may be started if required. Further tests may be advised for some women, especially if there is concern that there may be a cause for the heavy periods other than dysfunctional uterine bleeding. For example:

  • Women over the age of 40 who develop heavy periods.
  • If treatment for presumed dysfunctional uterine bleeding does not seem to help.
  • For someone in whom a large or abnormal uterus is detected on examination, or who has other symptoms which may indicate an underlying problem. For example, if you:
    • Bleed between periods, or have irregular bleeding.
    • Have bleeding or pain during, or just after, sex.
    • Have pain apart from normal period pains.
    • Have any change in your usual pattern of bleeding, particularly if you are over the age of 40.
    • Have symptoms suggesting a hormonal problem or blood disorder.

If tests are advised then they may include one or more of the following:

  • An ultrasound scan of your uterus. This is a painless test which uses sound waves to create images of structures inside your body. The probe of the scanner may be placed on your abdomen to scan the uterus. A small probe is also often placed inside the vagina to scan the uterus from this angle. An ultrasound scan can usually detect any fibroids, polyps, or other changes in the structure of your uterus.
  • Internal swabs. This may be done if an infection is the suspected cause of the heavy bleeding. A swab is a small ball of cotton wool on the end of a thin stick. It can be gently rubbed in various places to obtain a sample of mucus, discharge, or some cells. A swab is usually taken from the top of your vagina and also from your cervix. The samples are then sent away to the laboratory for testing.
  • Endometrial sampling. This is where a thin tube is passed into the uterus. Gentle suction is used to obtain small samples (biopsies) of the uterine lining (endometrium). This is usually done without an anaesthetic. This is more likely to be done if you are aged over 45 years, have persistent bleeding or have tried treatment without it helping. The samples are looked at under the microscope for abnormalities.
  • Hysteroscopy A thin telescope is passed into your uterus through your cervix via the vagina. This too can often be done without an anaesthetic. Small samples can also be taken during this test.
  • Blood tests. For example, if an underactive thyroid gland or a bleeding disorder is suspected.

It may be worth keeping a diary for a few periods (before and after any treatment). Your doctor may give you a chart which you can fill in. Basically, you record the number of sanitary towels or tampons that you need each day, and the number of days of bleeding. Also, note if you have any flooding or interruption of normal activities. For an example of a chart, see separate leaflet called 'Period Blood Loss Chart'. A diary is useful for both patient and doctor to see:

  • How bad symptoms are, and whether treatment is needed.
  • If treatment is started, to assess if it is helping. Some treatments take a few menstrual cycles to work fully. If you keep a diary it helps you to remember exactly how things are going.

Treatment aims to reduce the amount of blood loss. The treatment options will depend on the cause of heavy periods.


Not treating

This is an option if your periods do not interfere too much with normal life. You may be reassured that there is no serious cause for your heavy periods, and you may be able to live with them. A blood test may be advised every so often to check for anaemia. Iron tablets can correct anaemia.


Levonorgestrel intrauterine system (LNG-IUS)

This treatment usually works very well. The LNG-IUS is similar to an intrauterine contraceptive device (IUCD, or coil). It is inserted into the uterus and slowly releases a small amount of a progestogen hormone called levonorgestrel. The amount of hormone released each day is tiny but sufficient to work inside the uterus. In most women, bleeding becomes either very light or stops altogether within 3-6 months of starting this treatment. Period pain is usually reduced too. However, the light periods may become irregular. The LNG-IUS works mainly by making the lining of the uterus very thin.

The LNG-IUS is a long-acting treatment. Each device lasts five years, although it can be taken out at any time. It is particularly useful for women who require long-term contraception, as it is also a reliable form of contraception. This is, however, not usually suitable if you do not need long-term (for at least one year) contraception.


Tranexamic acid tablets

Tranexamic acid tablets are an option if the LNG-IUS is not suitable or not wanted. Treatment with tranexamic acid can reduce the heaviness of bleeding by almost half (40-50%) in most cases. However, the number of days of bleeding during a period is not reduced, and neither is period pain. You need to take a tablet 3-4 times a day, for 3-5 days during each period. Tranexamic acid works by reducing the breakdown of blood clots in the uterus. In effect, it strengthens the blood clots in the uterus lining which leads to less bleeding. If side-effects occur they are usually minor, but may include an upset stomach.


Anti-inflammatory painkillers

There are various types and brands. Most are available only on prescription but you can buy one called ibuprofen from pharmacies. Your doctor may prescribe ones called mefenamic acid, diclofenac or naproxen. These medicines reduce the blood loss by about a third (20-50%) in most cases. They also ease period pain. You need to take the tablets for a few days during each period. They work by reducing the high level of prostaglandin in the uterus lining which seems to contribute to heavy periods and period pain. However, they do not reduce the number of days the period lasts.

Side-effects occur in some people and may include an upset stomach. If you have a history of a duodenal or stomach ulcer, or asthma, you should only take these medicines on a doctor's advice.

Many women take both anti-inflammatory painkillers and tranexamic acid tablets for a few days over each period, as they work differently and this combination of tablets can be really effective for many women with heavy periods.


The combined oral contraceptive pill (COCP)

This reduces bleeding by at least a third in most women. It often helps with period pain too. It is a popular treatment with women who also want contraception, but who do not want to use the LNG-IUS. If required, you can take this in addition to anti-inflammatory painkillers (described above), particularly if period pain is a problem.


Long-acting progestogen contraceptives

The contraceptive injection and the contraceptive implant also tend to reduce heavy periods. For example, up to half of women on the contraceptive injection have no periods after a year. They are not given as a treatment just for heavy periods. However, if you require contraception then one of these may be an option for you.



Norethisterone is a progestogen medicine. It is not commonly used to treat heavy periods. It is sometimes considered if other treatments have not worked, are unsuitable or are not wanted. Norethisterone is given to take on days 5-26 of your menstrual cycle (day one is the first day of your period). However, taking norethisterone in this way does not act as a contraceptive.

The reason why norethisterone is not commonly used as a regular treatment is because many women get side-effects, such as bloating, fluid retention, breast tenderness, nausea, headache and dizziness. However, norethisterone is used as a temporary measure to stop very heavy menstrual bleeding.


Surgical treatment


It is an option if the above treatments do not help or are unsuitable:

  • Removing or destroying the lining of the uterus is an option. This is called endometrial ablation or resection (TCRE). An instrument is passed into the uterus via the vagina. The aim is to remove as much of the uterus lining as possible. This can be done by various ways such as by using heat, microwaves, and cryotherapy. This treatment may prevent women from having children in the future.
  • Hysterectomy is the traditional operation where the uterus is totally removed. However, hysterectomy is done much less commonly these days since endometrial ablation became available in the 1990s. It may be considered if all other treatment options have not worked for you.


Some women have very heavy bleeding during a period. This can cause a lot of blood loss, and distress. One option as an emergency treatment is to take a course of norethisterone tablets. Norethisterone is a progestogen medicine. Progestogens act like the body's natural progesterone hormones - they control the build-up of cells lining the womb.

Heavy periods due to dysfunctional uterine bleeding seem to be more common in the first few years after starting periods (and in the months running up to the menopause). If you are a teenager and have heavy periods, you have a good chance that they will settle down over a few years and become less heavy.


So, for example, if you take treatment for heavy periods whilst a teenager or young adult, it is very likely you will not need it after a few years.

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