Risks of HRT - Hormone replacement therapy (HRT)

Some types of HRT can increase your risk of certain serious problems, such as blood clots and breast cancer.

It's important to understand these risks.

HRT is only one way to improve your menopausal and postmenopausal health. There are other options.

For most women, the benefits of HRT outweigh the risks. Talk to your GP if you have any concerns about taking HRT.

Breast cancer

Taking combined HRT (oestrogen and progestogen) is linked to a small increased risk of breast cancer.

This increase is about a 0.5% - or 5 people in every 1,000.

The risk of breast cancer decreases when you stop taking HRT and may return to normal around 5 years after stopping HRT.

Taking oestrogen-only HRT is thought to cause little or no change in your risk of developing breast cancer.

Women taking combined HRT

For every 1,000 menopausal women taking combined HRT, 27 will develop breast cancer, 973 will not.

Women not taking combined HRT

For every 1,000 menopausal women not taking combined HRT, 22 will develop breast cancer, 978 will not.

Breast screening helps find cancer at an early stage

Attend all your breast cancer screening appointments if you're taking combined HRT.

Ovarian cancer

Experts are not sure if HRT can increase your risk of ovarian cancer.

But if there is any increased risk, they think the risk is very small.

A recent study found that for every 1,000 women taking HRT for 5 years, there will be 1 extra case of ovarian cancer.

Any risk of ovarian cancer is thought to decrease when you stop HRT.

Womb cancer

Oestrogen-only HRT can increase the risk of womb cancer (also called endometrial cancer). This is why it's only used in women who do not have a womb.

Taking combined HRT reduces this risk - particularly if you take a course of continuous HRT.

If you have a womb and you're taking combined HRT, it's important to take both medicines as advised by your GP. This will help to reduce your risk of womb cancer from HRT.

Blood clots

Blood clots can be serious if they block the flow of blood in a blood vessel.

Evidence shows that:

  • taking HRT tablets can increase your risk of blood clots
  • there's no increased risk of blood clots from HRT patches or gels

The risk of developing a blood clot is about 2 to 4 times higher than normal for women taking HRT tablets.

But as the risk of menopausal women developing blood clots is normally very low, the overall risk from HRT tablets is still small.


Content supplied by the NHS and adapted for Ireland by the HSE

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This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.

Page last reviewed: 7 July 2021
Next review due: 7 July 2024