What are the side-effects of HRT?

HRT works by replacing the hormones that naturally decline as you approach menopause with synthetic versions.

The main hormones used in HRT are:

• Oestrogen - regulates your menstrual cycle, develops female characteristics, and helps maintain bone and heart health.

• Progesterone - helps protect your womb (uterus) against abnormal changes - such as thickening of the womb lining (hyperplasia) or cancer - that can be caused by unopposed oestrogen. Progesterone is not needed for women who have had their womb removed (hysterectomy).

Dr Layla Eagles, Private GP, Wellsoon, Practice Plus Group, UK

Dr Layla Eagles, Private GP, Wellsoon, Practice Plus Group, UK, explains that the side effects of HRT are usually mild and often settle over time.

"Side effects can vary depending on how HRT is delivered," she says. "Oral tablets may be more likely to cause nausea or increase your chance of blood clots. Patches and gels tend to be gentler on your digestive system, and have a lower likelihood of causing blood clots."

She adds that implants offer a steady release of hormones, but they can be more difficult to adjust if side effects arise.

The side effects of HRT are often grouped into two categories, as many common symptoms are associated with either oestrogen or progestogen.

Eagles explains the typical side effects linked to each hormone.

Long-term oestrogen use may slightly raise your chance of blood clots or stroke - especially in tablet form.

Eagles says: "People with a history of migraines, clotting disorders, or hormone-sensitive cancers may be more vulnerable to side effects. Transdermal forms - such as patches or gels - are often preferred for people with existing cardiovascular concerns or conditions."

Eagles adds that natural (micronised) progesterone is generally better tolerated than synthetic progestins - especially for mood symptoms.

She says: "If side effects become intolerable, we can try a different type, dose, or delivery method, and in some cases consider alternatives - such as the Mirena coil."

Eagles explains that combined HRT, may increase your chance of developing breast cancer slightly more than oestrogen-only HRT.

She says: "If you have had a hysterectomy, you usually don’t need the progesterone component and can take oestrogen alone, which is generally considered a safer option."

How long do HRT side-effects last?

Most HRT side effects are short-term and usually improve within 3-6 months as your body gets used to the treatment.

"We typically review patients at 3 months after starting," says Eagles. "This assessment then becomes annual unless issues arise, with the option to review sooner if symptoms persist or new ones develop."

Reporting HRT side-effects

The Medicines and Healthcare products Regulatory Agency (MHRA) Yellow Card scheme is an easy way to report suspected issues with medicine in the UK. Reports can be submitted online or via the Yellow Card scheme app on Apple or Google Play. Submissions go directly to experts who review and investigate your concerns.

Risks associated with HRT

Long-term use of HRT - particularly with oral combined HRT - may leave you vulnerable to developing breast cancer, blood clots or stroke.

Eagles advises, however, that for many people under 60 - or within 10 years of menopause - the advantages often outweigh the potential downsides.

She says: "We always consider personal and family history, and HRT may need to be used cautiously if you have migraines, liver issues, or heart disease."

Your doctor will explain what the treatment involves, what you can expect from it, and any other available options to help you make an informed choice.

"Changes in diet, exercise, alcohol, and stress levels can also help," says Eagles. "It’s worth asking your doctor about what the treatment involves, what you can expect from it, other available options, and how HRT may interact with any existing conditions before starting treatment."