You may have read in the press or heard people discuss that women taking hormone replacement therapy (HRT) are prone to blood clots in their veins. The purpose of this leaflet is to explain the benefits and risks, and what this means for you.

The benefits of HRT

HRT relieves symptoms of the menopause and when taken for several years prevents fractures by reducing thinning of the bones (osteoporosis). It has also been suggested that it may reduce heart disease, but this has not been fully evaluated.

The risk of a blood clot

New information was published in a medical journal in October 1996 which suggests that blood clots in the veins are more common in women who take HRT whatever the type. However, the chance of getting a blood clot is low regardless of whether or not you take HRT.

Chances of getting a blood clot:

Not taking HRT 1 in 10,000 per year
While taking HRT 3 in 10,000 per year

What are the consequences of a blood clot?

Blood clots can occur in any vein but are most common in the legs (deep vein thrombosis or DVT) where they may cause pain, swelling or redness. If this occurs patients may require certain tests and a few days treatment in hospital. Occasionally blood clots pass to the lungs, this is more serious but usually responds to treatment.

How serious can a blood clot be?

Most people who get a blood clot in a vein make a complete recovery after treatment so the chance of dying from a blood clot is very low indeed. If you are not taking HRT your chance of dying from a blood clot is 1 in a million per year while if you are taking HRT your chance is 3 in a million per year.

What to do if you are concerned

The risk of blood clots is low and needs to be balanced against the benefits that HRT may have for you. If you are already on HRT, you do not need to stop it. If you are concerned about what you have heard or read and would like to discuss these concerns further, make a routine appointment to see your doctor who can talk through the pros and cons of HRT with you.

Source: CSM 1997