Hormone replacement therapy (HRT) has been used for decades to ease the transition through perimenopause and menopause. For a long time, it was seen almost as a “must” for all women. Then, large studies — especially the Women’s Health Initiative (WHI) in the early 2000s — raised serious concerns about breast cancer and heart disease risks. Many women stopped treatment, and confusion has lingered ever since.
More recent evidence paints a more nuanced picture: HRT can be highly effective and safe for many women when used in the right way, at the right time, and for the right reasons. This blog pulls together key insights from a 2025 review article in the Journal of Clinical Medicine to explain how HRT is used today.
What Is Hormone Replacement Therapy?
Hormone replacement therapy is designed to replace hormones the ovaries no longer produce in sufficient amounts — mainly estrogen and progesterone, and sometimes androgens like testosterone.
It aims to:
- Relieve menopausal symptoms, especially:
- Hot flashes and night sweats (vasomotor symptoms)
- Vaginal dryness and discomfort (genitourinary syndrome)
- Sleep disturbances and mood swings
- Prevent long-term health issues associated with low estrogen, particularly:
- Osteoporosis and fractures
- Unfavorable changes in cholesterol and glucose metabolism
- Increased cardiovascular risk
HRT is not a one-size-fits-all solution. The type, dose, and route of administration must be adapted to each woman’s age, symptoms, medical history, and personal preferences.
Important: This blog is informational only and does not replace medical advice. Always discuss HRT decisions with a qualified healthcare professional.
Understanding Menopause and Its Types
The Menopause Transition
A woman’s reproductive life spans from puberty through the reproductive years to menopause. This process is driven by the hypothalamic–pituitary–ovarian axis, which regulates hormones such as follicle-stimulating hormone (FSH), Luteinizing hormone (LH), estrogen, and progesterone.
- Perimenopause (the menopause transition):
- Usually begins in the mid‑40s and lasts about 4–8 years.
- Characterized by hormonal instability, irregular cycles, and anovulation.
- AMH and inhibin B decrease, FSH increases, and estradiol fluctuates.
- Up to 80% of women experience hot flashes and night sweats; mood issues and cognitive changes are common.
- Menopause (by definition):
- No menstrual periods for 12 consecutive months, not due to another medical cause.
- Typically occurs between ages 45 and 55.
Types of Menopause
- Natural menopause
- The usual, age-related loss of ovarian function (average onset ~51 years).
- Diagnosis is clinical: at least 1 year of amenorrhea (absence of menstruation) plus typical symptoms.
- Early menopause (age 40–45)
- Oligomenorrhea (infrequent or light menstruation), amenorrhea ≥3 months.
- Confirmed by elevated FSH (on two measurements)
- Needs evaluation because it affects long‑term health risk.
- Premature Ovarian Insufficiency (POI, <40 years)
- Menopause before 40 due to genetic, autoimmune, iatrogenic, or unknown causes.
- Affects ~3–4% of women.
- Marked by elevated FSH and low estrogen.
- Strong indication for HRT up to the usual age of natural menopause.
- Induced or surgical menopause
- Caused by bilateral oophorectomy, chemotherapy, gonadotropin agonists/antagonists, or pelvic radiation.
- Hormone levels drop abruptly, often causing intense symptoms.
- Associated with a rapid rise in cardiovascular and metabolic risk.
How Menopause Affects the Body
Hormone Shifts
After menopause, estrogen levels fall, while bioavailable androgens (like testosterone) can become relatively higher. This shift:
- Promotes visceral fat gain (belly fat)
- Increases risk of:
- Obesity
- Type 2 diabetes
- Cardiovascular disease
- Nonalcoholic fatty liver disease
- Metabolic syndrome
At the same time, LDL cholesterol, which was previously used as a substrate for estrogen production, is no longer utilized and tends to accumulate in the bloodstream, contributing to atherogenic lipid profiles (a blood lipid pattern indicating a high risk for developing atherosclerosis).
Bone Health
Estrogen plays a key role in maintaining bone mass. Around menopause:
- Bone loss accelerates; about 20% of lifetime bone loss occurs around this period.
- Over 20 years post-menopause:
- Trabecular bone can drop by ~50%
- Cortical bone by ~30%
- Up to 50% of postmenopausal women may develop osteoporosis, leading to fractures, disability, and increased mortality.
Cardiovascular and Metabolic Consequences
Menopause is linked with:
- Higher LDL cholesterol
- Insulin resistance
- Central obesity
- Higher rates of hypertension and cardiovascular disease
Surgical menopause, with its sudden loss of estrogen and progesterone, particularly raises risks for endothelial dysfunction, atherosclerosis, and cardiovascular events.
Where HRT Fits In
HRT is the gold standard for treating moderate to severe menopausal symptoms and has major benefits for:
- Vasomotor symptoms (hot flashes, night sweats)
- Genitourinary syndrome (vaginal dryness, pain with intercourse, urinary symptoms)
- Prevention of osteoporosis and fractures in high‑risk women
- Improving metabolic profile (better HDL, lower LDL, improved insulin sensitivity)
Meta‑analyses show that HRT:
- Increases lean body mass
- Reduces abdominal fat
- Improves insulin resistance (HOMA‑IR)
- Lowers fasting glucose in women with or without diabetes
- Favors a healthier lipid profile
However, these benefits must be weighed against potential risks such as breast cancer, venous thromboembolism, stroke, and endometrial cancer.
When Is HRT Recommended?
Major organizations like NAMS (North American Menopause Society), NICE (UK), and the British Menopause Society (BMS) agree on core principles:
Ideal candidates
HRT is generally considered beneficial and relatively low risk for:
- Women under 60 or
- Within 10 years of their final menstrual period, who
- Have moderate to severe symptoms or significant osteoporosis risk, and
- Do not have major contraindications.
Strong indications
- Premature ovarian insufficiency (POI)
- Early menopause (<45), especially if surgically or medically induced
- Symptomatic women with distressing vasomotor or urogenital symptoms
- High risk of osteoporotic fractures
Key treatment principles
- Individualise therapy
- Consider age, time since menopause, comorbidities, family history, body weight, and personal preferences.
- Use the lowest effective dose
- Aim for symptom control with the minimum dose, and reassess annually.
- Choose route and formulation carefully
- Transdermal or vaginal routes are often preferred in women at higher thrombotic or cardiovascular risk.
- Review regularly
- First review around 3 months after starting to check symptoms, side effects, blood pressure, and bleeding.
- Then at least annually for breast exam, risk reassessment, and metabolic markers.
HRT does not reliably prevent pregnancy. Women in early menopause using HRT still need contraception for a period (commonly 1–2 years, depending on timing and guidance).
Types of HRT: Hormones and Formulations
Estrogen
Estrogen is central to relieving hot flashes, night sweats, vaginal atrophy, and preventing bone loss.
Common forms in HRT:
- 17β‑estradiol (bioidentical to natural estrogen)
- Available as oral tablets, transdermal patches, gels, sprays, and vaginal preparations.
- Oral estradiol has low bioavailability (~5%) due to first‑pass liver metabolism, shifting the estradiol:estrone ratio and influencing clotting and lipid parameters.
- Transdermal and vaginal routes bypass first‑pass metabolism, often lowering thrombotic risk and providing steadier hormone levels.
- Conjugated equine estrogens (CEE)
- Derived from pregnant mare urine; include equilin and estrone sulfate.
- Orally active and relatively potent.
- Ethinylestradiol
- A synthetic estrogen with high oral bioavailability and potency.
- Common in oral contraceptives, but rarely used in modern HRT due to higher thrombotic and metabolic impact.
Side effects of estrogen therapy often improve within 3–6 months and can include:
- Fluid retention, bloating
- Breast tenderness
- Nausea, headache
- Leg cramps
- Breakthrough vaginal bleeding
Progesterone and Progestins
For women with a uterus, estrogen must be balanced with a progestogen to protect the endometrium from hyperplasia and cancer.
- Natural micronised progesterone
- Bioidentical, with no androgenic activity.
- Favored for its more favorable metabolic and cardiovascular profile.
- Synthetic progestins
- Progesterone derivatives: e.g. medroxyprogesterone acetate, dydrogesterone.
- Testosterone derivatives: e.g., norethisterone, levonorgestrel, desogestrel.
- Often more potent orally, but some carry higher risk of adverse effects on lipids, vessels, and breast tissue, especially at higher doses.
Regimens:
- Sequential (cyclic)
- Estrogen is given continuously.
- Progestogen added for 10–14 days per cycle.
- Often used in perimenopause; can lead to withdrawal bleeding.
- Continuous combined
- Estrogen and progestogen given together daily.
- Typically used in fully postmenopausal women; aims to avoid bleeding.
- Intrauterine levonorgestrel system
- Can be used to protect the endometrium while providing systemic estrogen by another route.
Testosterone and Tibolone
- Testosterone
- Considered for women with low libido, profound fatigue, or surgical/early menopause.
- Available as patches, gels, or implants.
- Must be carefully dosed to avoid androgenic side effects (acne, hair changes), cardiovascular risks, and possible breast effects.
- Tibolone
- A synthetic steroid with estrogenic, progestogenic, and androgenic activity.
- May improve hot flashes, mood, and sexual function and prevent bone loss.
- Generally does not cause withdrawal bleeding in postmenopausal women.
- May increase stroke risk in women over 60 and risk of breast cancer recurrence; use is contraindicated in women with a history of breast cancer.
SERMs (Selective Estrogen Receptor Modulators)
SERMs act like estrogen in some tissues (e.g. bone) and as anti‑estrogen in others (e.g. breast, sometimes endometrium). They can:
- Help with bone protection
- Avoid stimulating breast tissue
They may be used alone or in combination strategies for specific indications.
Routes of Administration
HRT can be delivered as:
- Oral tablets
- Transdermal patches, gels, sprays, creams
- Vaginal tablets, creams, rings, pessaries
- Subcutaneous implants
- Intrauterine devices (for progestin)
Choice depends on:
- Presence/absence of the uterus
- Cardiovascular and thrombotic risk profile
- Liver and gallbladder status
- Predominant symptoms (e.g. local vaginal vs systemic)
- Patient preference and lifestyle
HRT vs. Oral Contraceptives: Key Differences
Although both HRT and combined oral contraceptives (COCs) contain estrogen and progestin, they are quite different in purpose and design.
Oral contraceptives:
- Aim to suppress ovulation by shutting down the hypothalamic–pituitary–ovarian (HPO) axis.
- Use higher doses and more potent synthetic hormones (e.g. ethinylestradiol plus synthetic progestins).
- Indicated for women of reproductive age (roughly 15–45) for:
- Contraception
- Cycle regulation
- Acne
- Endometriosis and PCOS management
Hormone replacement therapy:
- Does not suppress the HPO axis; it replaces deficient hormones.
- Uses lower doses, often bioidentical estradiol with progesterone/progestin.
- Target population is perimenopausal and postmenopausal women.
- Focus is on symptom relief and long‑term health protection, not contraception.
Women may transition from contraceptives to HRT around the time of natural menopause, depending on their symptoms and health status.
Risks and Contraindications of HRT
HRT’s benefits must be weighed against potential risks, which vary by:
- Age and time since menopause
- Type, dose, and route of hormone(s)
- Duration of use
- Personal and family history of cancer, thrombosis, and cardiovascular disease
Main Risks
- Venous thromboembolism (VTE)
- Oral estrogen can increase clotting factors (II, VII, IX, X) and decrease antithrombin III.
- VTE risk is highest in the first year of treatment and in high‑risk women (obesity, thrombophilia, family history, smokers).
- Transdermal estradiol is preferred in women at elevated VTE risk because it bypasses the liver.
- Cardiovascular disease and stroke
- Oral estrogen can increase pro‑inflammatory and pro‑thrombotic factors in the vessel wall.
- Starting HRT late (many years after menopause, or after an event) is more concerning.
- Timing matters: starting within 10 years of menopause in healthy women appears safer and may even reduce some cardiovascular outcomes.
- Breast cancer
- Estrogen stimulates breast glandular tissue; adding certain progestins can further increase proliferation.
- Risks are linked to the type of progestogen, duration of use, and age at initiation.
- Long‑term combined estrogen+progestin therapy increases breast cancer risk more than estrogen alone.
- Natural micronised progesterone appears to carry a more favorable breast safety profile than several synthetic progestins.
- Endometrial cancer
- Unopposed estrogen in women with an intact uterus significantly increases the risk of endometrial hyperplasia and carcinoma.
- Adding an appropriate dose and schedule of progestogen markedly reduces this risk.
- Ovarian cancer
- Some data suggest a modest increase in ovarian cancer risk with long‑term estrogen use, which declines after stopping therapy.
- Transdermal routes may mitigate some risk, but evidence is still evolving.
- Gallbladder disease
- Oral estrogens increase cholesterol saturation in bile and the risk of gallstones.
- Transdermal preparations are associated with lower gallbladder risk.
- Testosterone and tibolone-specific risks
- Testosterone: possible androgenic side effects, lipid changes, cardiovascular concerns, and uncertain breast impact, especially at supraphysiologic doses.
- Tibolone: increased stroke risk in older women; possible increased risk of breast cancer recurrence and some endometrial effects.
Absolute Contraindications
HRT is generally avoided in women with:
- Current or past breast cancer or other hormone-sensitive malignancies (e.g. endometrial cancer)
- Unexplained vaginal bleeding (until fully investigated)
- Active or recent venous thromboembolism (DVT, PE), particularly when estrogen is planned
- Significant cardiovascular disease or prior myocardial infarction or ischemic stroke (unless a specialist advises otherwise)
- Uncontrolled hypertension
- Active severe liver disease
- Known hypersensitivity to the product
Relative Contraindications
These may permit carefully selected, typically lower‑risk regimens after individual risk–benefit analysis:
- Migraine with aura (often favoring low‑dose transdermal estrogen or avoiding systemic estrogen entirely)
- Well-controlled hypertension
- Hypertriglyceridemia
- Gallbladder disease
- Uterine fibroids, endometriosis (which may be estrogen‑sensitive)
How Doctors Choose the Right HRT
A typical stepwise approach includes:
- Confirming menopausal status and type
- Natural vs early vs Premature Ovarian Insufficiency (POI) vs induced/surgical.
- Checking for uterus presence
- Uterus present: combined estrogen + progestogen.
- Uterus absent: estrogen alone.
- Selecting regimen by life stage
- POI / early menopause: cyclic combined HRT, usually until at least the age of normal menopause.
- Perimenopause: sequential combined therapy (continuous estrogen, cyclic progestin).
- Postmenopause (<60 years and within 10 years of menopause): continuous combined therapy (if uterus), or estrogen alone (if hysterectomy).
- Matching route to risk factors
- Transdermal or vaginal estrogen for higher VTE or cardiovascular risk; oral options for low‑risk women.
- Vaginal-only regimens for mainly genitourinary symptoms.
- Monitoring and adjusting
- Check symptom relief and side effects at ~3 months.
- Annual reviews of breast health, blood pressure, weight, and metabolic labs.
- Deciding when and how to stop
- No universal “expiration date” — duration is individualized.
- Some women benefit from longer-term therapy.
- Gradual dose tapering is generally recommended rather than abrupt cessation.
- Local vaginal estrogen may be used long term for persistent urogenital symptoms.
Take‑Home Messages for Women Considering HRT
- HRT remains the most effective treatment for troublesome hot flashes, night sweats, and vaginal symptoms, and it helps prevent bone loss.
- The benefits are often greatest for women who start treatment before age 60 and within 10 years of menopause.
- Not all HRT is the same: the type of estrogen, the type of progestogen, dose, and route all influence both benefits and risks.
- For many women, especially those at higher clot or cardiovascular risk, transdermal and vaginal routes offer a safer profile than oral estrogen.
- HRT is not a contraceptive; contraceptive needs should be discussed separately if you are in early menopause and still at risk of pregnancy.
- Decisions about starting, continuing, or stopping HRT should be personalized, based on your symptoms, health history, family history, and preferences — and revisited regularly with your clinician.
If you’re struggling with menopausal symptoms or worried about long‑term bone and heart health, it’s worth having an in‑depth conversation with your healthcare provider about whether HRT, and which type, might be appropriate for you.
