Hormone replacement therapy (HRT)

Page last reviewed: 13/07/2011

Hormone replacement therapy (HRT) is a treatment used to replace the female hormones that a woman's body is no longer producing because of the menopause.

The menopause - sometimes known as the 'change of life' - occurs when levels of the female hormones oestrogen and progesterone fall and your ovaries stop producing eggs. Menstruation (your periods) ends and you are no longer able to conceive (become pregnant).

Oestrogen and progesterone have very important roles in a woman's body. When levels fall, this causes a wide range of physical and emotional symptoms. HRT can restore these hormone levels and enable the body to function normally again.

The role of oestrogen

Oestrogen plays an important role in the release of eggs from the ovaries. It regulates a woman's periods and helps her to conceive.

Oestrogen also helps to regulate many other body functions, including bone density, the temperature of your skin and keeping the vagina moist. It is the reduction of oestrogen that causes most of the symptoms associated with the menopause, including:

  • hot flushes
  • vaginal dryness
  • loss of sex drive
  • mood changes
  • stress incontinence (leaking urine when you cough or sneeze)
  • night sweats
  • thinning of the bone, which can lead to brittle bones (osteoporosis)

Most of these symptoms pass within two to five years, although vaginal dryness is likely to get worse if it is not treated. The risk of osteoporosis also increases with age.

The role of progesterone

The main function of progesterone is to prepare the womb for a possible pregnancy. It also helps to protect the lining of the womb (endometrium).

A falling level of progesterone does not have the same wide-ranging effects on your body as falling levels of oestrogen. However, it increases your risk of developing cancer of the womb lining (endometrial cancer).

Therefore, progesterone is usually used in combination with oestrogen in HRT (although women who have had a hysterectomy do not need progesterone and can take oestrogen-only HRT). See HRT - types for more information.

Benefits and risks

If you are concerned about any risks associated with HRT you should discuss them with your doctor.

Page last reviewed: 13/07/2011

Hormone replacement therapy (HRT) can begin once you start having menopausal symptoms.

The average age for women to have the menopause is 52. However, some women experience it when they are still in their forties, or as late as their sixties. There is no way of predicting when the menopause will occur.

You may have menopausal symptoms before your actual menopause starts - this is known as the peri-menopause. The peri-menopause happens because the levels of oestrogen and progesterone fall when your number of remaining eggs drops below a certain level. It means women can experience menopausal symptoms even when they are still having periods.

In most cases, you can take HRT without taking a test to confirm that you are starting the menopause.

Testing for the menopause is usually only necessary if you are under 40 or experiencing unusual bleeding patterns during your period. These tests can rule out other conditions that may cause similar symptoms, such as having an overactive thyroid gland (hyperthyroidism) or cervical cancer.

When HRT is not suitable

HRT may not be suitable if you:

  • have a history of breast, ovarian or endometrial cancer
  • have a history of blood clots
  • have a history of heart disease or stroke
  • have untreated high blood pressure (your blood pressure will need to be controlled before you can start HRT)
  • have liver disease
  • are pregnant

Under these circumstances, different medicines may be prescribed to help control your symptoms. See HRT - alternatives for more information.

Page last reviewed: 13/07/2011

Hormone replacement therapy (HRT) replaces the two female hormones that a woman's body is no longer producing because of the menopause. These hormones are:

  • oestrogen - the oestrogen used in HRT is taken from plants or from the urine of pregnant horses
  • progesterone - HRT uses a synthetic version of progesterone known as progestogen (which is used because it is easier for the body to absorb)

There are more than 60 different preparations of HRT, but the three main types are discussed below.

Oestrogen-only HRT

This type of HRT is usually recommended for women who have had their womb and ovaries removed by hysterectomy. As you no longer have a womb, you do not need to take progestogen because there is no risk of endometrial cancer (cancer of the womb lining).

Cyclical HRT

Cyclical HRT (also known as sequential HRT) is recommended for women who are experiencing menopausal symptoms but still have their periods.

There are two types of cyclical HRT:

  • monthly HRT - where you take oestrogen every day and also take progestogen at the end of your menstrual cycle for 14 days
  • three-monthly HRT - where you take oestrogen every day and also take progestogen for 14 days every 13 weeks

Monthly HRT is normally recommended for women who are having regular periods. You will continue to have monthly periods until your menopause causes them to stop.

Three-monthly HRT is normally recommended for women who are having irregular periods. You should experience your period every three months.

It is useful to maintain regular periods so you know when your periods naturally stop, and when you are likely to progress to the last stage of the menopause.

Continuous combined HRT

Continuous combined HRT is usually recommended for women who are post-menopausal. A woman is normally defined as being post-menopausal if she has not had a period for a year.

As the name suggests, continuous HRT involves taking oestrogen and progestogen every day, without a break.

Choosing the right HRT

  • Aim to chose a relatively low dose of HRT hormones to begin with. It is best to start with the lowest effective dose to minimise any side effects. You can always increase your dose at a later date if needed.
  • Persevere with your HRT. Give it a few months to see if it works well for you. If it does not work, you can try a different type or dose.
  • Always talk to your GP about any doubts or problems you are having with your HRT.

Pregnancy and HRT

The oestrogen used in HRT is different from the oestrogen used in the contraceptive pill, and it is not as powerful.

This means it is still possible to become pregnant if you are taking HRT to control menopausal symptoms. In some cases, a woman can be fertile for up to two years after her last period if she is under 50, or for a year if she is over 50.

If you do not wish to become pregnant, use a non-hormonal method of contraception, such as a condom or diaphragm.

Page last reviewed: 13/07/2011

There are several different ways that hormone replacement therapy (HRT) can be taken. These include:

  • a cream or gel, which can be applied to the skin or directly into the vagina if you are experiencing vaginal dryness
  • tablets, which can be taken by mouth or placed directly into your vagina to treat dryness
  • a patch that you stick on your skin
  • an implant - your doctor inserts small pellets of oestrogen under the skin of your abdomen (tummy), buttock or thigh under a local anaesthetic (the skin is numbed)

If you are only experiencing vaginal dryness, you will probably be advised to use a form of HRT that can be applied directly to the vagina. Tablets, patches or implants are only required if you have other menopausal symptoms, such as hot flushes.

As there are so many different combinations of HRT, you may find it difficult to decide which is the best for you. Your GP will have a great deal of experience in helping women with their menopause and will be happy to provide advice.


The hormones used in HRT are normally prescribed at the lowest possible dose to control your symptoms. It may take a while to establish the best dose. Tell your GP if you feel that your current dose is not working properly.

When to stop taking HRT

Most women should be able to stop taking HRT once their menopausal symptoms have finished. This is normally between two to five years.

It is usually recommended that you decrease your dose of HRT gradually over time, rather than stopping suddenly. You may have a relapse of menopausal symptoms once you stop HRT, but these should pass in a few months.

If symptoms persist for several months after stopping HRT, or are particularly severe, contact your GP as your treatment may need to be restarted. It can usually be restarted at a lower dose.

Once your HRT has finished, you may need additional treatment for vaginal dryness and to prevent osteoporosis. Creams and lubricants are available for vaginal dryness, and there are medicines called bisphosphonates that have proved to be successful in the treatment of osteoporosis.

Page last reviewed: 13/07/2011

If you are unable or unwilling to take hormone replacement therapy (HRT), some alternative approaches and treatments may help to control symptoms of the menopause. These are discussed below.

Lifestyle changes

Lifestyle changes may help to ease menopausal symtoms. Such changes including:

  • Taking regular exercise - this has been shown to reduce symptoms of hot flushes and improve sleep. Regular exercise is also a good way of boosting your mood if you feel anxious, irritable or depressed.
  • Cooling down at night - wearing loose clothes and sleeping in a cool, well-ventilated room may help relieve hot flushes and night sweats.
  • Cutting down on caffeine, alcohol and spicy food - these have all been known to trigger hot flushes.
  • Quitting smoking - if you are a smoker, quitting will help to reduce symptoms of hot flushes and reduce your risk of developing serious health conditions, such as heart disease, stroke and cancer.


Tibolone is a synthetic hormone that can be used as an alternative to HRT. It contains a combination of oestrogen and progestogen, so you only need to take one tablet.

Tibolone has the same associated health risks as continuous combined HRT. If you are unable to take HRT for medical reasons - for example, you have a history of breast cancer or heart disease - it is likely you will not be able to take tibolone.


The following antidepressants have proved effective in treating hot flushes in some women:

  • Selective serotonin reuptake inhibitors (SSRIs) - paroxetine, fluoxetine or citalopram.
  • Serotonin-noradrenaline reuptake inhibitors (SNRIs) - venlafaxine.

Side effects of these antidepressants include:

  • nausea
  • blurred vision
  • diarrhoea or constipation
  • dizziness
  • dry mouth 
  • loss of appetite
  • sweating
  • feeling agitated
  • insomnia (not being able to sleep)

SSRIs have also been associated with a loss of libido (sex drive).

Side effects usually improve over time. See your GP if they do not. You may need to have regular blood tests or blood pressure checks when taking antidepressants, especially if you also take the anti-clotting drug warfarin or you have high blood pressure.


Clonidine is a medicine originally designed to treat high blood pressure, but studies have shown that it may reduce hot flushes in some women.

Side effects of clonidine include:

  • low blood pressure
  • dizziness
  • drowsiness
  • dry mouth
  • fluid retention

Using clonidine is not recommended if you have depression or insomnia, as it could make these conditions worse.

Alternative medicines

Claims have been made for a number of herbal supplements for the treatment of the menopause. These include:

  • soya beans
  • ginseng
  • ginkgo biloba
  • black cohosh
  • red clover
  • kava

There is no clear evidence that any of these are effective. Little is known about their long-term effects.

Kava and red clover have been linked to liver disease. Avoid taking black cohosh, ginseng and red clover if you have a history of breast, ovarian or endometrial cancer, as there is some evidence they could trigger a relapse of the condition.

Page last reviewed: 13/07/2011

Each of the hormones used in hormone replacement therapy (HRT) is associated with certain side effects.

Side effects normally improve over time, so it is best to stick with the treatment plan you have been prescribed for at least three months. If side effects continue after this time, see your GP so that your treatment plan can be looked at again.

If side effects persist, your GP may recommend:

  • switching to a different way of taking your HRT, for example, changing from a tablet to a patch, or vice versa
  • changing the type of HRT you take, for example, a different form of oestrogen or progestogen
  • changing the dose of your HRT

Side effects of oestrogen

Side effects associated with oestrogen include:

  • fluid retention
  • bloating
  • breast tenderness or swelling
  • nausea
  • leg cramps
  • headaches
  • indigestion

In some cases, making small lifestyle changes can help to relieve side effects. For example:

  • taking your oestrogen dose with food may help to reduce nausea and indigestion
  • eating a low-fat, high-carbohydrate diet may reduce breast tenderness
  • regular exercise and stretching can help to reduce leg cramps

Side effects of progestogen

Side effects associated with progestogen include:

  • fluid retention
  • breast tenderness
  • headaches
  • mood swings
  • depression
  • acne
  • backache

Weight gain

Many women believe that taking HRT will make them gain weight, but there is no evidence that this is the case. It is common to gain some weight at the time of the menopause, but this will often happen whether you take HRT or not. Regular exercise and a healthy diet should help you lose any unwanted weight

Page last reviewed: 13/07/2011

If you are concerned about any risks associated with HRT you should discuss them with your doctor.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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