The Medicines and Healthcare Products Regulatory Agency (MHRA) and the Committee on Safety of Medicines (CSM) in the UK has prepared a summary of what is currently known about the risks and benefits of HRT.


Short-term treatment of menopausal symptoms

For short-term use of HRT for the relief of menopausal symptoms, the benefits outweigh the risks in most women. HRT therefore remains a suitable treatment option. However, the lowest effective dose should be used for the shortest duration and treatment should be reviewed at least annually.

Prevention of osteoporosis

For long-term use in preventing osteoporosis in women over 50 years of age, the balance of risks and benefits is unfavourable (see below). HRT should only be used for preventing osteoporosis by those who are unable to take other osteoporosis prevention treatments or for whom other treatments have been unsuccessful.

Women who have had a premature menopause

HRT may be used in younger women who have experienced a premature menopause (due to ovarian failure, surgery or other causes) for treating menopausal symptoms and for preventing osteoporosis until the age of 50 years. After this age, the choice of therapy for preventing osteoporosis should be reviewed.

If you have concerns about your HRT treatment, you should make a routine appointment to discuss this information with your doctor.

What is HRT and what can it be used for?

When you reach menopause, your levels of the hormones oestrogen and progestogen naturally fall. This fall in hormone levels causes your menstrual cycle to become irregular and your periods eventually to stop. This may also cause some of the unpleasant symptoms of the menopause, such as hot flushes and vaginal dryness. Hormone replacement therapy, also known as HRT, provides low doses of these hormones to replace those that your body no longer produces. There are two main types of HRT – oestrogen-only HRT and combined HRT that contains both oestrogen and progestogen. Oestrogen-only replacement products are now available as: tablets, implants, patches, vaginal rings, gels and a nasal spray.

In combined HRT products, the oestrogen and progestogen may be taken in the same tablet or patch or they may be taken separately. The progestogen may be taken every day (continuous combined HRT) or for 12-14 days of each monthly treatment cycle (sequential combined HRT).

HRT can be used by: women with postmenopausal symptoms, women who are at a high risk of osteoporosis and fractures but who unable to take other osteoporosis prevention therapies or for whom other treatments have been unsuccessful, younger women who have experienced a premature menopause (due to ovarian failure, surgery or other causes) for treating menopausal symptoms and for preventing osteoporosis until the age of 50 years.

What are the benefits of HRT?

HRT is effective in relieving the symptoms of the menopause. These symptoms may include: hot flashes, night sweats, vaginal dryness and discomfort, difficulty sleeping, depression, mood swings, tiredness and poor concentration,

In most cases, using HRT for a short period of time is enough to relieve these symptoms, although they may recur for a short time after stopping HRT. Some HRT products can also be taken for a longer time to help prevent osteoporosis (thinning of the bones) and so reduce the risk of hip fractures. However, because of the known risks of HRT long-term treatment, and because the risks of many of these conditions increase as you become older, HRT should only be used to prevent osteoporosis in women for whom other medicines are unsuitable or have been unsuccessful. HRT may also be used to prevent osteoporosis in younger women who have had an early menopause, until the age of 50 years.
Some studies have shown that HRT reduces the number of cases of colon cancer. It was previously thought that HRT was beneficial in the prevention of heart disease, but evidence now shows this is not the case.

What are the risks of HRT?

As well as benefits, HRT has some risks which you need to consider when you’re deciding whether to start HRT or to carry on taking it. As with all medicines, the use of HRT is associated with some side-effects. While many women have no side effects, nausea, breast tenderness, weight gain and fluid retention occur fairly commonly. Long-term use of HRT may increase the risk of getting some potentially more serious but much rarer conditions (see below). The risk of getting many of these conditions also increases as you get older. Key information about each of these risks is given below. It is important to remember that all these conditions can occur without using HRT and that a woman’s risk of getting any of these conditions depends on her own health, her lifestyle and her family medical history. To help put these risks into perspective, the extra number of cases of each of these conditions associated with HRT is typically smaller than the health risks associated with smoking or being very overweight. For some of these risks, studies have allowed us to estimate the number of extra cases that will occur in a five or ten year period as a result of using HRT.

Heart disease Studies have shown that some products (that contain conjugated oestrogens and MPA) do not prevent heart disease and may make the chance of getting heart disease more likely in the first year of taking them. For other types of HRT, the picture is still unclear, but there is nothing to suggest that their effect on the heart will be any different. HRT does not prevent heart disease and should not be used to protect against heart disease. You should stop HRT and seek urgent medical attention if you experience episodes of chest pain, possibly related to exercise, with or without sweating, breathlessness or dizziness.

Stroke Research suggests that HRT increases the risk of having a stroke. Taking average women in their 50s who do not use HRT, 3 in a thousand are expected to have a stroke in any five year period. For women of the same age who use HRT for 5 years, the expected number of strokes will be 4 in a thousand. The risk of stroke increases as a woman gets older so taking women in their 60s who do not use HRT 11 in a thousand will be expected to have strokes in any five year period. This compares with 15 in a thousand women of the same age who use HRT for 5 years. You should stop HRT and seek urgent medical attention if you experience unusual migraine-type headaches or unusual faints or limb weakness.

Blood clots (venous thromboembolism, VTE) The risk of harmful blood clots in the veins is increased by taking HRT, especially in the first year. Taking average women in their 50s who do not use HRT, 3 in a thousand would get blood clots over five years. In women of the same age who use HRT for 5 years, that figure would be 7 in a thousand. The risk of VTE increases with age and so 8 in a thousand women in their 60s who do not use HRT could get clots over five years. This compares with 17 in a thousand women in their 60s who use HRT for 5 years. You should stop HRT and seek urgent medical attention if you experience a red, swollen or painful leg or sharp pains in your chest with breathlessness or feeling faint.

Breast cancer Using oestrogen-only HRT slightly increases the chance of breast cancer. For combined (oestrogen plus progestogen) HRT the risk is higher than for oestrogen-only therapy. Tibolone (Livial
, a different type of HRT product) also increases the risk of breast cancer but not as much for combined HRT. In all cases, the risk of breast cancer begins to decline when HRT is stopped and by 5 years reaches the same level as in women who have never taken HRT.
Taking women aged 50 who do not use HRT, about 32 in every thousand will be diagnosed with breast cancer by the time they reach the age of 65 years. For women who start oestrogen-only HRT at age 50 and take it for five years, the total number of cases would be between 33 and 34 in every thousand (ie an extra 1-2 cases). If they take it for ten years, there would be 37 in a thousand (ie an extra 5 cases).
By comparison, for women who start combined HRT at age 50 the number of cases of breast cancer that would be diagnosed by the time they reach 65 would be 38 in a thousand after 5 years use (ie an extra 6 cases) and 51 in a thousand after 10 years use (ie an extra 19 cases). The numbers have not been calculated for tibolone but are thought to lie somewhere between those for oestrogen-only and combined HRT. It is important that you note any changes in your breasts and, if you are 50 or over, to attend for breast screening. You should make an appointment to see your doctor if you notice any changes to your breasts including skin changes, nipple changes or lumps.

Endometrial cancer(cancer of the lining of the uterus) Taking oestrogen-only HRT for a long time increases the risk of cancer in the uterus lining (endometrium). For women who have not had their uterus removed by hysterectomy their doctor can prescribe a progestogen as well as an oestrogen to reduce this risk. You should make an appointment to see your doctor if you notice any abnormal vaginal bleeding which continues or starts some months after starting HRT, this may include heavy bleeding, irregular bleeding or bleeding regularly after sex.

Ovarian cancer Using oestrogen-only HRT for more than 5 years may slightly increase the risk of this rare cancer. The effect of long-term combined HRT on the ovaries is not yet known. You should make an appointment to see your doctor if you experience abdominal swelling and discomfort, weight loss and/or abnormal vaginal bleeding, possibly associated with an abdominal lump.

What medical check-ups do I need if I’m using HRT?

Before you start taking HRT, your doctor should ask about your own and your family’s medical history. Your doctor may decide to examine your breasts and/or your abdomen, and may do an internal examination — but only if these examinations are necessary for you, or if you have any special concerns. Once you have started HRT, you should see your doctor for regular check-ups (at least once a year). At these check-ups, your doctor may discuss with you the benefits and risks of continuing to take HRT. It is important that you are ‘breast aware’, whether you take HRT or not. You should know what is normal for you, know what to look and feel for, and to report any changes to your GP without delay. You are also encouraged to accept your invitations for breast screening from the age of 50. Be sure to: go for regular breast screening and cervical smear tests, regularly check your breasts for any changes such as dimpling of the skin, changes in the nipple, or any lumps you can see or feel.

What types of HRT have been studied?

Much of the evidence about the long-term risks of combined HRT relates to one product used in the United States a continuous combined tablet that contains conjugated oestrogens (0.625mg) plus the progestogen medroxyprogesterone acetate (MPA, 2.5mg). This is similar to the UK products Premique (0.625mg conjugated oestrogens plus 5mg MPA) and Premique cycle (0.625mg conjugated oestrogens plus 10mg MPA).
While we can’t say for sure whether the long-term risks that have been identified also apply to other combined HRT regimens, there is currently little evidence to suggest that there is any difference in the risks with different combined HRT products. Similarly, while some studies looking at the effects of oestrogen-only HRT have used specific types of oestrogens, there is little evidence to suggest that there is a difference in the risks with different oestrogen-only products.
Regarding the risk of breast cancer, one large study in the UK looked at all types of HRT, including oestrogen-only, combined (oestrogen plus progestogen) HRT and tibolone. This study showed that within ‘oestrogen–only’ products the risk of breast cancer was not changed by the type of oestrogen or whether it was given as a tablet, patch or implant etc. Similarly, within ‘combined HRT’ products the risk was not changed by the type of progestogen or the number of days it was taken per cycle.

Where can I find further information?

There are other more minor side effects of HRT that are not discussed here. You are advised to always read the Patient Information Leaflet that is supplied with your medicine. If you are concerned about any new symptoms that you feel may be related to your HRT you should speak to your doctor, pharmacist or practice nurse. The Medicines and Healthcare products Regulatory Agency (MHRA) and the Committee on Safety of Medicines (CSM) has prepared a summary of what is currently known about the risks and benefits of HRT.