The Risks of HRT

• As with all medicines, the use of HRT is associated with some side-effects. While a large number of 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). 

• 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 year period due to 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 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 - Recent 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 could 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 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 HRT for 5 years or more slightly increases the chance of breast cancer. The risk from HRT increases the longer you use it but is thought to return to normal within 5 years of stopping. Taking women aged 50 who do not use HRT, about 45 in every thousand will be diagnosed with breast cancer by the time they reach the age of seventy. For women who start HRT at age 50 and take it for five years, the figure would be 47 in every thousand. If they take it for ten years, it would be 51 in a thousand. If they take it for fifteen years, it would be 57 in a thousand.
    You should take advantage of the breast screening checks offered under the national programme, and you should make an appointment to see your doctor if you notice any changes to your breasts including skin changes, nipple changes or lumps.
    
    
  • Cancer of the lining of the womb - taking oestrogen-only HRT for a long time increases the risk of cancer in the womb lining (endometrium). For women who have not had their womb removed by hysterectomy their doctor will normally 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 but serious 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.

  Prepared from advice from The Medicines Control Agency (MCA) and the Committee on Safety of Medicines (CSM)

Last edited 07/08/08