What are the risks of HRT?

For most women, the risks of HRT (hormone replacement therapy) are small, and both the HSE and the NHS say the benefits usually outweigh them. Recent evidence says the risk of serious side effects is very low. The risks that do exist depend on the type of HRT you take, how long you take it and your own health. Your GP can help you weigh them up for you.

Why HRT got a bad name

If you remember worrying news stories about HRT, you’re not imagining it. The NHS says older studies made many people reluctant to take or prescribe HRT, but that view is now seen as out of date.

The HSE says the benefits are likely to outweigh the risks if you:

• are under 60
• have menopause symptoms
• are not at high risk of breast cancer or blood clots
• start HRT within 10 years of becoming menopausal

That doesn’t mean HRT is right for everyone, and it doesn’t mean women outside that group can’t take it. It means the balance needs a closer look with your GP.

Breast cancer

This is the risk most women ask about first, so here are the numbers.

Combined HRT (oestrogen plus a progestogen, the type most women with a womb take) can slightly increase the risk of breast cancer. The HSE and NHS both say there are around 5 extra cases of breast cancer in every 1,000 women who take combined HRT for 5 years.

The risk goes up the longer you take combined HRT, and the older you are. It falls again after you stop. The older HSE risks page says it may return to normal around 5 years after stopping.

Oestrogen-only HRT, which is for women who have had a hysterectomy (an operation to remove the womb), causes little or no increase in breast cancer risk, according to the HSE, NHS and NICE.

If you’ve had breast cancer, the HSE and NHS say you’ll usually be advised not to take HRT. Whatever type you use, keep going to your breast screening appointments.

Blood clots and stroke

Blood clots. HRT tablets can increase the risk of a blood clot in a vein, but the HSE and NHS say the risk is still very low. HRT patches, sprays and gels do not increase the risk of blood clots, because the oestrogen is absorbed through your skin. NICE says that if you’re already at higher risk of clots, you may be offered patches or gel instead of tablets, and with a strong family history of clots you may be referred to a specialist first.

Stroke. HRT tablets (but not patches, gel or spray) slightly increase the risk of stroke. Both the HSE and NHS say the risk is very low, particularly if you’re under 60.

This is one of the most useful things to know: the form of HRT can change the risk, so it’s worth asking your GP whether a patch, gel or spray would suit you.

Womb and ovarian cancer

Womb cancer. Taking oestrogen on its own can increase the risk of womb cancer if you still have a womb. That’s why, the HSE explains, women with a womb are usually prescribed oestrogen together with a progestogen, which protects the womb lining. If that’s you, take both parts as your GP advises.

Ovarian cancer. The HSE says experts are not sure whether HRT increases the risk. If it does, they think the risk is very small: one study found 1 extra case for every 1,000 women taking HRT for 5 years. The risk is thought to fall after stopping.

Heart disease, diabetes and dementia

• Heart disease. HRT has little or no effect on the risk of coronary heart disease, according to the HSE and NHS. NICE says starting HRT before 60 does not increase your risk of cardiovascular disease.
• Type 2 diabetes. HRT does not increase the risk, and the HSE and NHS say some recent studies suggest it may even slightly reduce it.
• Dementia. It’s not known whether HRT changes the risk of dementia. The NHS says research is ongoing and any risk or benefit is likely to be small.

Vaginal oestrogen

Vaginal oestrogen (creams, pessaries or a ring used for vaginal dryness) is a much lower dose. The HSE and NHS both say it does not increase the risk of breast cancer, blood clots or other conditions.

Common side effects

Separate from these longer-term risks, some women get side effects, especially in the first few months. The NHS says it’s common to have none, or only minor ones. Those listed by the NHS and HSE include headaches, breast tenderness, nausea, mood changes and unexpected spotting or bleeding. If they don’t settle, talk to your GP, as a different type or dose may suit you better.

When to get help straight away

The HSE and NHS side effects pages list these as emergencies. Call 112 or 999, or go to the emergency department (don’t drive yourself), if you have:

• chest pain and breathlessness
• difficulty speaking or moving an arm or leg, or one side of your face drops

Contact your GP, or call 112 or 999, urgently if you have pain, redness or swelling in one leg, usually the calf, which can be a sign of a blood clot.

See your GP soon if you notice a breast lump or other breast changes, or changes in vaginal bleeding after you’ve been on HRT for more than a few months.

Ireland and the UK

The guidance on risks is essentially the same in both countries. In Ireland, HRT is free at participating pharmacies with a medical card or Drugs Payment Scheme card (our guide explains how). In the UK, talk to your GP or practice nurse; the NHS also says a pharmacist can talk you through HRT options. For the different forms, see our guide to the types of HRT.

What to do next

• Write down your own risk factors before your appointment: any personal or family history of breast cancer, blood clots, stroke or heart disease.
• Ask your GP these three questions: What are the benefits for me? What are the risks for me, as a number? Would a patch, gel or spray suit me better than tablets?
• Book or keep your breast screening appointments, especially if you take combined HRT.
• Keep reviewing it. The risks change with age and how long you take HRT, so check in with your GP regularly. Never stop or change HRT without talking to them first.