For two decades after the 2002 Women’s Health Initiative, hormone replacement therapy was widely avoided based on a single trial whose results have since been re-analyzed and contextualized. Modern guidance from major societies including the North American Menopause Society and ACOG describes hormone therapy as the most effective treatment for moderate to severe vasomotor symptoms, with a favorable benefit-risk profile for healthy women under 60 or within 10 years of menopause. Understanding what the current evidence actually says — and where uncertainty remains — helps women and clinicians make informed decisions.
What Hormone Replacement Therapy Is
Hormone replacement therapy, increasingly called menopausal hormone therapy (MHT) by clinical societies, replaces estrogen and (when the uterus is present) a progestogen to alleviate symptoms of estrogen deficiency. It is used primarily for vasomotor symptoms, genitourinary syndrome of menopause, and prevention of osteoporosis in women at significant fracture risk who cannot tolerate other agents.
According to the NAMS 2022 Hormone Therapy Position Statement, “for women aged younger than 60 years or who are within 10 years of menopause onset and have no contraindications, the benefit-risk ratio is favorable for treatment of bothersome vasomotor symptoms and for those at elevated risk for bone loss or fracture.” For broader context, see our guide to women’s health conditions.
Who Is a Candidate (and Who Is Not)
Good candidates include women with bothersome hot flashes or night sweats, those experiencing sleep disruption from menopause symptoms, women with genitourinary syndrome of menopause unresponsive to vaginal estrogen alone, and those with primary ovarian insufficiency or surgical menopause before the natural age — for whom hormone therapy is generally recommended at least until age 51 to mitigate cardiovascular and bone risks.
Contraindications, per the ACOG Practice Bulletin, include unexplained vaginal bleeding, known or suspected estrogen-sensitive cancer (especially breast cancer), active or recent venous thromboembolism, active liver disease, recent stroke or myocardial infarction, and pregnancy. Cautions include hypertriglyceridemia, gallbladder disease, migraine with aura, and active smoking after age 35.
Types of Hormones and Routes of Delivery
Estrogen options include 17-beta estradiol (the same molecule the ovaries produce, available as oral tablets, transdermal patches, gels, sprays, and vaginal preparations), conjugated equine estrogens, and esterified estrogens. Transdermal estradiol bypasses first-pass liver metabolism and carries lower thrombotic risk than oral estrogen, per a meta-analysis in BMJ. This makes it preferred for women with elevated baseline clot risk, migraine, or hypertriglyceridemia.
Progestogens are required for women with an intact uterus to prevent endometrial hyperplasia. Micronized progesterone (Prometrium) is the bioidentical option and may have a more favorable breast and metabolic profile than synthetic progestins, according to studies summarized by NAMS. Other options include medroxyprogesterone acetate, norethindrone acetate, and the levonorgestrel-releasing IUD, which provides effective endometrial protection.
“Bioidentical” hormones — meaning estradiol and micronized progesterone — are FDA-approved and widely available through standard pharmacies. Compounded “bioidentical hormone therapy” prepared by compounding pharmacies is not FDA-regulated for purity, dose accuracy, or clinical outcomes, and NAMS specifically advises against routine use of compounded hormone therapy when FDA-approved options exist.
Benefits Backed by Evidence
Hormone therapy reduces hot flash frequency and severity by approximately 75 percent in randomized trials. It improves sleep quality in women whose sleep is fragmented by night sweats. It treats vaginal atrophy and dyspareunia, though local vaginal therapy is preferred when genitourinary symptoms are the primary concern. It preserves bone density and reduces vertebral and hip fractures by roughly 30 to 40 percent in the WHI estrogen arm.
For women starting hormone therapy under age 60 or within 10 years of menopause, observational data and re-analysis of WHI data suggest possible cardiovascular benefits — the so-called “timing hypothesis” — though this is not an indication for therapy on its own. Quality of life, mood symptoms, and joint aches often improve as well, per data summarized in Menopause.
Risks and How to Think About Them
Risks vary by formulation, route, dose, and a woman’s baseline health. The 2022 NAMS statement quantifies key risks. Combined estrogen-progestogen therapy is associated with a small increase in breast cancer risk after about five years of use — roughly less than 1 additional case per 1,000 women per year of use. Estrogen-alone therapy showed no increased breast cancer risk and possibly a slight decrease in the WHI follow-up.
Oral estrogen is associated with a roughly 2-fold increased risk of venous thromboembolism, while transdermal estradiol does not appear to elevate clot risk meaningfully. Stroke risk is slightly elevated with oral estrogen but not transdermal in observational data. Endometrial cancer risk is increased with unopposed estrogen in women with a uterus, which is why a progestogen is essential.
Common side effects in the first few months include breast tenderness, breakthrough bleeding, headache, bloating, and mood changes. Most diminish with time or dose adjustment.
When to See a Doctor
Anyone considering hormone therapy should have an individualized risk-benefit conversation. A NAMS-certified menopause practitioner is well-positioned for this discussion. Annual reassessment is recommended, focusing on whether symptoms still warrant treatment and whether the woman’s risk profile has changed.
While on therapy, see a clinician promptly for new breast lump, unscheduled vaginal bleeding lasting more than three to six months after starting, persistent pelvic pain, or signs of liver dysfunction. Routine breast cancer screening with mammography should continue per age-appropriate guidelines.
When to seek emergency care: Call 911 or go to the nearest emergency room if you experience sudden chest pain or shortness of breath, calf pain or swelling, severe headache, one-sided weakness or facial droop, sudden vision change, or coughing up blood — these may indicate clot, stroke, or pulmonary embolism.
Frequently Asked Questions
Does HRT cause weight gain?
Hormone therapy does not cause significant weight gain on average. The WHI showed no statistically significant weight difference between hormone and placebo groups. Bloating and breast fullness are common in the first few weeks but usually resolve.
How long can you stay on hormone therapy?
NAMS no longer recommends a strict duration limit. The decision to continue is individualized based on symptoms, benefits, risks, and preferences, with annual reassessment. Many women safely continue therapy beyond age 65 if benefits outweigh risks.
Are bioidentical hormones safer than synthetic ones?
FDA-approved estradiol and micronized progesterone are bioidentical, and some evidence suggests micronized progesterone has a more favorable breast profile than medroxyprogesterone acetate. Compounded bioidentical hormones, however, are not FDA-regulated and have no demonstrated safety advantage — NAMS advises against their routine use.
Can I start HRT years after menopause?
The benefit-risk balance becomes less favorable when initiated more than 10 years past menopause or after age 60, particularly for cardiovascular outcomes. Vaginal estrogen for genitourinary symptoms can still be appropriate at any age. Systemic therapy in late postmenopause warrants careful individualized discussion.
The Bottom Line
For most healthy women in their 40s and 50s with bothersome menopause symptoms, hormone therapy is a reasonable, evidence-based option that has been unfairly maligned for two decades. The choice between transdermal versus oral estrogen, micronized progesterone versus other progestogens, and dose level should be individualized. Newer non-hormonal options like fezolinetant give more women effective alternatives. A clinician up to date on current menopause guidance can help you weigh your specific symptom burden, risk factors, and preferences.