HRT Side Effects and Risks: What Every Woman Should Know

What Is HRT and How Does It Work?

HRT replaces the oestrogen (and usually progesterone) your ovaries produce less of during perimenopause and menopause. By restoring these hormones to more comfortable levels, HRT relieves symptoms like hot flushes, night sweats, vaginal dryness, mood disruption, and sleep problems.

There are two main types:

• Combined HRT — oestrogen plus a progestogen. Used if you still have a uterus (the progestogen protects the uterine lining).
• Oestrogen-only HRT — used after a hysterectomy.

Both are available as tablets, patches, gels, sprays, or implants. The route and type of hormone matter significantly for your risk profile.

Common HRT Side Effects (Usually Temporary)

Most side effects appear in the first few weeks as your body adjusts. They tend to settle within 3 months.

Oestrogen-related side effects:

• Breast tenderness or swelling
• Nausea (more common with oral tablets)
• Headaches or migraines
• Leg cramps
• Bloating

Progestogen-related side effects:

• Mood changes, low mood, or irritability
• Acne or oily skin
• Lower libido
• Fluid retention
• Irregular spotting in the first few months

Important: Many women who struggle with one type of progestogen do well on another. Micronised progesterone (body-identical progesterone) has a more favourable side-effect profile and is associated with better sleep compared to synthetic progestogens in clinical data.

The Bigger Picture: What Are the Real Risks?

Breast Cancer

The 2002 Women's Health Initiative (WHI) trial found a small increase in breast cancer risk with combined HRT (oestrogen + synthetic progestogen). The absolute increase was approximately 8 extra cases per 10,000 women per year — comparable to the risk increase associated with drinking one to two glasses of wine daily or being overweight.

Key nuances: The WHI used a specific formulation. Oestrogen-only HRT (for women without a uterus) was actually associated with a reduced risk of breast cancer. Transdermal oestrogen combined with micronised progesterone appears to carry lower breast cancer risk than oral combined HRT, based on the large French E3N cohort study.

The International Menopause Society (IMS) is clear: for healthy women under 60 who are within 10 years of menopause onset, the benefits of HRT generally outweigh the risks.

Blood Clots (Venous Thromboembolism / VTE)

Oral HRT tablets increase the risk of deep vein thrombosis (DVT) and pulmonary embolism — but transdermal HRT does not carry this same risk. NICE NG23 explicitly states that transdermal HRT is the preferred route for women with risk factors for VTE.

Stroke

Oral HRT is associated with a small increase in stroke risk. Transdermal oestrogen does not appear to carry this risk. Women with a personal or family history of stroke should discuss transdermal options with their doctor.

Cardiovascular Disease

Women who start HRT early (within 10 years of menopause — the "window of opportunity") actually show cardiovascular benefits in many studies, including reduction in coronary heart disease risk and all-cause mortality. The IMS recommends that HRT should not be withheld from healthy younger postmenopausal women on cardiovascular grounds.

Body-Identical vs Synthetic Hormones: Does It Matter?

Yes. "Body-identical" hormones — oestradiol and micronised progesterone — are chemically identical to hormones your body produces. Evidence increasingly supports their use over older synthetic formulations: better side-effect profile, improved sleep outcomes, lower breast cancer risk associations, and better tolerability.

Who Should Be Cautious About HRT?

HRT may not be suitable for women with: oestrogen-receptor positive breast cancer; unexplained vaginal bleeding; untreated high blood pressure; active liver disease; history of blood clots; recent stroke or heart attack. A thorough medical assessment is essential.

Frequently Asked Questions

Does HRT cause weight gain?
HRT itself does not cause weight gain. Weight changes during menopause are primarily driven by hormonal shifts and metabolic changes, not by HRT.

How long can I take HRT?
NICE NG23 advises there is no mandatory time limit. Duration should be reviewed annually based on ongoing benefits and individual risk factors.

Is there a safer form of HRT?
Transdermal oestrogen combined with micronised progesterone currently has the most favourable evidence profile for minimising VTE, stroke, and breast cancer risks.

Can I take HRT if I have a family history of breast cancer?
A family history (without a confirmed genetic mutation like BRCA1/2) does not automatically rule out HRT. Individual risk assessment with a specialist is important.

What happens when I stop HRT?
Menopause symptoms may return when HRT is stopped. Gradual tapering is generally recommended over abrupt cessation.

Take the Guesswork Out of Menopause

Zoey connects you with women's health doctors in Singapore who specialise in menopause care — so you can get personalised, evidence-based advice and a treatment plan that works for your body.

→ Speak to a Zoey doctor today — online consultations available across Singapore.