E F Nigel Holland
Consultant Gynaecologist and Obstetrician
Menu Patient Information Leaflet 12 – Hormone Replacement Therapy (HRT) - Back to List


There is still much disagreement and conflicting evidence about the uses and safety of Hormone Replacement Therapy (HRT). Drug companies who manufacture HRT have much to gain from its widespread use. Claims that it is a cure-all for ever/ mid-life problem have been common in the press and its benefits oversold and problems minimised.

On the other hand many women suffering with severe menopausal symptoms have undoubtedly been helped by taking HRT. It may be essential for some women who have had their ovaries removed or who have had an early menopause and are at risk of osteoporosis.        

The experience of the menopause is very individual and the symptoms are temporary (usually lasting six months to two years). The symptoms can be helped in a variety of ways and HRT is one of the options. Every woman should be able to decide for herself whether or not to take HRT. Making the decision can only be done by comparing the pros and cons of taking HRT in the light of guidance from the Committee on Safety of Medicines and with the woman taking into account, her own particular needs, priorities and health background.

This leaflet gives general information about HRT.

What is HRT?

HRT is designed to increase levels of the female hormone oestrogen which fall as women go through the menopause.

Oestrogen is responsible for the development and maintenance of female sex organs and breasts and also helps to maintain the lining of the vagina and to keep other body tissues moist and flexible. The crucial difference between HRT and other hormonal treatments is that HRT is prescribed to counteract this natural reduction in the level of oestrogen which occurs at the menopause. In other cases, such as an under-active thyroid, hormonal treatment is given because glands are not functioning properly and a dangerous deficiency could result without treatment.

Some medical writers have referred to the menopause as a 'deficiency condition' as though it was an unnatural event. However, the menopause is not an illness.

Oestrogen production from the ovaries falls at the time of the menopause or following removal of, or damage to the ovaries. But oestrogen continues to be made from other hormones in fatty tissues and in the adrenal glands. As the oestrogen from the ovaries fluctuates and declines during the menopause, the body goes through a period of readjustment. The menopause, rather than being a time of deficiency, could be providing biological protection. For example, oestrogen can promote the development of certain types of breast cancers, so a natural reduction in oestrogen circulating in the body could be an advantage.

Oestrogen is used in HRT to stabilise oestrogen levels in the body as production declines. The oestrogen used may be synthetic or derived from the urine of pregnant horses (Premarin. Prempak-C, Premique, Premique Cycle) or from plants.

Progesterone is another female hormone which helps to bring about menstrual periods, prepares the womb to receive a fertilized egg, maintains pregnancy and affects the development of the breasts in pregnancy. It is added into HRT in the form of progestogen to prevent cancer of the womb lining (see cancer of the womb lining). There are various types of progestogens, some are derived from progesterone and some from testosterone.

Testosterone therapy has also been advocated by some doctors. Testosterone is mostly made by the ovaries and women who have had their ovaries removed during hysterectomy may notice a loss of sex drive. Testosterone supplements in the form of patches are an experimental therapy prescribed by some doctors alongside conventional HRT (i.e. oestrogen and progestogen) but they cause side effects, such as increase in body hair, and so they need to be uses with caution

What can HRT be used for?

The Committee on Safety of Medicines has issued guidance about the safe use of HRT for women aged 50 and over. Although some doctors say the advice is too cautious and the risks of HRT exaggerated, this advice will influence how doctors prescribe HRT for the time being. Research studies are very complex and open to criticism and not all doctors have interpreted the findings in the same wav.

HRT can be used for the short-term relief of menopausal symptoms

HRT can be used as a short-term treatment to help women who have menopausal symptoms. These usually last around six months to two years or so, and include symptoms such as hot flushes and night sweats. A dry vagina, disturbed sleep, headaches, poor memory, panic attacks, loss of sex drive and aching joints. Some women have only minor symptoms whilst others can be severely affected. HRT is acknowledged as a beneficial treatment for hot flushes, night sweats and vaginal problems. Some women feel generally much better using HRT. But current safety advice is that HRT should be used for the shortest possible time at the lowest effective dose, with treatment reviewed annually in consultation with a doctor.

Bone health

HRT is no longer recommended as the first choice of treatment for the prevention of osteoporosis. HRT does protect again osteoporosis but the protection lasts only as long as women take HRT which in effect means long-term treatment. Though the increased risks are small, the longer that HRT is taken the greater the opportunity for risk.

Dietary and life-style measures are the best way to protect bones. If treatment is needed other drugs will be tried first before HRT. but if these do not work, HRT may be appropriate. HRT can also be given to prevent osteoporosis in younger women who have been through a premature menopause.

Premature menopause

Women who have a menopause before the age of 45 can take HRT until the age of 50, to counter menopausal symptoms and to prevent osteoporosis. It is thought that taking HRT before 50 does not lead to the increase in risks detailed in HRT Risks.

What are the Positive Effects and the Side Effects of taking HRT?

The positive effects of HRT

Evidence indicates that HRT controls hot flushes and night sweats which for some women can be a major problem. HRT also improves vaginal lubrication, relieving vaginal soreness due to dryness.
Some women report that they generally feel better on it, that it improves mood and concentration, reduces joint pains and forgetfulness and increases sexual desire. Because of all this, some women want to stay on HRT for as long as they can despite the risks.


HRT reduces hip fractures. For example, in women aged 50-59, there are 1-2 cases of hip fracture for every 1,000 non-HRT users, compared to 0-1 cases for every 1,000 HRT users.

Colon Cancer

HRT also reduces the risk of colon cancer. In women aged 50-59 there were 3 cases of colon cancer reported in 1,000 non-HRT users compared to 1 case less in 1,000 HRT users.

HRT Risks

Recent research about the safety and benefits of HRT has changed medical advice about what HRT can be used for. HRT was recommended for the relief of menopausal symptoms, but it was also sometimes recommended to healthy women (without menopausal symptoms) as a long-term treatment to help prevent osteoporosis and offer protection against heart disease and other problems of ageing, such an Alzheimer's disease.

The Committee on Safety of Medicines no longer recommends HRT is as safe to use for a long-term treatment because of safety concerns (detailed below). The concerns have been raised by-recent studies including the Million Women Study (2003, UK trial) and the Women's Health Initiative (2002, US trial).

Summary of risks from the Medicines and Healthcare Products Regulatory Agency and the Committee on Safety of Medicines

The increased risks of taking HRT are small. Women who do not take HRT can also develop these conditions. Any risk assessment needs to take into account a range of factors including life-style and family history.

Breast Cancer

  • Women who do not take HRT: About 32 in every 1000 women aged 50 (who do not take HRT) will get breast cancer by the time they reach 65.
  • Oestrogen only HRT: In women aged 50 who take oestrogen only HRT for 5 years, about 33.5 in every 1000 will get breast cancer. That is only an extra 1-2 cases. If they take it for 10 years his could rise to 37 cases in a 1000. Results from the oestrogen only study form the Women's Health Initiative released in early 2004 found that women who took oestrogen only HRT had no increased risk of breast cancer.
  • Combined HRT starter at age 50: The number of cases that would be diagnosed by 65 would be 38 cases in 1000 after 5 years i.e. an extra 6 cases, and 51 in 1000 after 10 years, i.e. an extra 19 cases. Results from a recent Swedish study found that continuous combined 'bleed-free' products carried the highest risk.
  • Tibolone: The risks of breast cancer have not been studied for this product but are thought to be between those for oestrogen only and combined HRT.

Cancer of the Womb Lining

Taking oestrogen only HRT makes the womb lining thicken, and this increases the risk of cancer developing. This risk is reduced (but not totally eliminated) by taking progesterone which gets rid of any excess womb lining in the form of a withdrawal bleed. Any abnormal bleeding which begins after starting HRT needs to be investigated.

HRT after breast cancer

The advice on this is changing and it is thought that even short-term use of HRT may pose a risk for women with a history of breast cancer. The evidence is not clear but early results from a Swedish trial in 2004 suggest that HRT increases the risk of recurrent breast cancer. Women with menopausal symptoms should discuss options very carefully with their specialist.

These are small pellets containing oestrogen which are inserted under the skin. They usually contain a 6 month supply of hormones and are inserted into the fatty layers of the abdomen, buttocks or thighs under a local anaesthetic. This means that the dosage is fixed for the specific time. If intolerable side effects occur, the implant has to be removed, but locating it may be difficult and removal may be painful. Implants can result in higher oestrogen levels than tablets or patches. With implants, the body may get accustomed to high oestrogen levels and as a result some women may experience more side effects as the oestrogen in the implant runs out. However, some women find this a very convenient method as once the implant is in place they can forget about it. Women with a womb will need progestogen in some form as well.

Ovarian Cancer

Using oestrogen only HRT for more than 5 years may slightly increase the risk of getting this rare but serious cancer. It is not vet known what effect combined HRT has on ovarian cancer.

Heart Disease

The latest advice is that HRT does not protect against heart disease as was previously though. Also products which contain conjugated oestrogen (oestrogen from the urine of pregnant mares) and a type of progestogen called medroxyprogesterone may increase the risk of heart disease in the first year of use.


HRT slightly increases the risk of having a stroke. For women in their 50 "s who do not take HRT about 3 in every 1000 will have a stroke in any 5 year period compared to about 4 in 1000 women of the same age who take HRT for 5 years.

Stroke risk goes up with age. For women in their 60’s who do not take HRT, about 11 in 1000 will have a stroke over a 5 year period compared to about 15 in 1000 women who use HRT for 5 years.

Venous thromboembolism

Harmful clots can develop in the veins. If a clot develops in the deep veins of the legs it is called a Deep Vein Thrombosis (DVT). If a part of the clot breaks off and moves into the lungs it can cause a potential life threatening obstruction called a pulmonary embolism. The term venous thromboembolism (VTE) covers both deep vein thrombosis and pulmonary embolism.

Research shows that women who take HRT are more likely to develop a VTE than those who don't, especially in the first year of using HRT: for women in their 50:s who do not use HRT, about 3 in 1000 will have a VTE over 5 years compared to 7 in 1000 women of the same age who use HRT for 5 years.


Contrary to what was previously thought, research currently shows that HRT has no beneficial effect on mental functioning and may increase the risk of dementia later in life.

Weighing up the risks

Despite the current safety recommendations, it is important to emphasise that the increase in risks identified by these studies is small (in a study done by the Imperial Cancer Research Fund, reported in the late 1990's. the risks linked to HRT rapidly reduced after stopping HRT and disappeared after 5 years). Each women needs to discuss the pros and cons of HRT with their doctor to see if it is suitable for them. Some doctors may agree to prescribe HRT for longer for those women who feel that the benefits of HRT outweigh its risks.

Reducing HRT risk

At the moment some research suggests that oestrogen only products may have a lower breast cancer risk than combination products but this needs to be confirmed by further research. Many women need to take progestogen because they still have a womb. It may be safe to deliver progestogen with the Mirena device, although more research is needed to confirm this. Some doctors believe this might be a better option as the progestogen just acts in the womb rather than affecting the whole body.

Leaflet complied by: Mr Nigel Holland, Consultant Gynaecologist & Obstetrician (North Cheshire Hospitals)
Ratified by: Womens Health Directorate June 2006


back to the top of the page

all content © Nigel Holland 2005-2010