What it is:Menopausal hormone therapy (MHT/HRT) replaces the estrogen the ovaries stop making, given alone or paired with a progestogen, to treat vasomotor symptoms (hot flashes, night sweats) and vulvovaginal atrophy. It is still the single most effective treatment for moderate-to-severe hot flashes, full stop.
The core problem:As the ovaries run out of follicles, estradiol production collapses (>90% drop) and FSH/LH climb 10 to 15-fold trying to compensate. Every downstream symptom, thermoregulatory, vaginal, sleep, bone, is a tissue losing its estrogen signal.
What you do about it:Individualize by four things: does she have a uterus, is it vasomotor or vulvovaginal symptoms (or both), how far out from menopause is she, and does she have a contraindication. Then default to transdermal estradiol at the lowest effective dose, paired with a non-medroxyprogesterone progestogen if the uterus is intact.
This whole chapter is a timing problem, not just a drug problem. The exact same estrogen dose is cardioprotective if started within about 6 years of menopause (or before age 60) and can be harmful if started after 10 years. Every risk number in this chapter (VTE, stroke, breast cancer, dementia) has to be read against whentherapy started, not just whetherit was started.
Four stages, and they're defined by menstrual history, not symptoms:
| Stage | Definition | Typical age |
|---|---|---|
| Premenopause | Regular cycles, normal ovarian function | Avg. 46 |
| Perimenopause | Onset of menstrual irregularity; hormones swing high and low unpredictably as follicles deplete | Avg. onset 50 (symptoms can start 7–10 years before the last period) |
| Menopause | Diagnosed retrospectively: 12 consecutive months of amenorrhea | Avg. 51 (95% of women: 45–55) |
| Postmenopause | Everything after that 12-month mark | ~40% of a woman's expected lifespan |
Perimenopause is not infertile.Estrogen can spike as easily as it dips during this window, so ovulation still happens unpredictably. Anyone sexually active in perimenopause still needs contraception, and hormonal contraceptives can double as symptom treatment here since their estrogen doses are much higher than MHT doses.
Diagnostic workupis mostly a history, not a lab panel: comprehensive history and physical, CBC, and serum FSH, with thyroid dysfunction and pregnancy specifically ruled out as mimics. If FSH is checked (day 2–3 of a cycle), a value >10–12 IU/Lsignals diminished ovarian reserve. At full menopause you'll see FSH rise 10 to 15-fold, LH rise 4 to 5-fold, and estradiol fall more than 90%, the same negative-feedback logic as a failing thyroid driving TSH sky-high.
The hypothalamic-pituitary-ovarian axis runs the whole show. GnRH from the hypothalamus drives pituitary release of FSH and LH, which drive the ovary to make estradiol (from the dominant follicle) and progesterone (from the corpus luteum), plus a smaller amount of androgens (testosterone, androstenedione) from the ovarian stroma. Estradiol and progesterone then feed back negatively on the pituitary to keep the cycle in check.
As follicles run out with age, that feedback loop breaks: less estradiol means less negative feedback, so FSH and LH climb higher and higher trying to force a response the ovary can no longer give. Eventually estradiol production essentially stops. What estrogen remains postmenopause is mostly estrone, made by converting adipose tissue, not the ovary, which is part of why obesity changes a patient's symptom profile and risk calculus.
Every MHT decision traces back to one fact: estrogen receptors sit in the hypothalamic thermoregulatory center, the vaginal and urethral mucosa, and bone. Replace estradiol and you're not treating a disease, you're restoring a signal those tissues lost. That's also why the drug classes split the way they do: systemic estrogenfor thermoregulation and bone, local vaginal estrogenwhen only the urogenital tissue needs the signal back.
The one place estrogen replacement causes a problem instead of solving one is the endometrium. Unopposed estrogen drives endometrial proliferation and, over time, hyperplasia and cancer risk (a 4 to 8-fold increase with unopposed estrogen in a uterus that's still present). This is the exact mirror image of progestin-only contraception, which thins the endometrial lining. That's why anyone with an intact uterus needs a progestogen added, and anyone without one (prior hysterectomy) doesn't.
| Category | Findings |
|---|---|
| Vasomotor | Hot flushes, night sweats, the single most reported symptom and the one estrogen treats best (close to 100% response) |
| Sleep / mood / cognition | Sleep disturbance, depression, anxiety, poor concentration and memory |
| Urogenital | Vaginal dryness, dyspareunia, urogenital atrophy; unlike hot flashes, this tends to worsenthe longer someone is postmenopause instead of fading |
| Other | Headache, sexual dysfunction, arthralgia |
| Metabolic | Central abdominal fat gain, lipid shifts, vascular effects, accelerated bone loss |
| Perimenopause-specific | Dysfunctional uterine bleeding |
Abnormal bleeding in perimenopause needs other causes ruled out before you chalk it up to hormones. And vasomotor symptoms get blamed for everything, but sleep disturbance, mood changes, and memory complaints are independently documented symptoms, not just downstream dominoes of a hot flash. Symptom severity and pattern also vary meaningfully by race and ethnicity, so don't assume a textbook presentation.
Goals of therapy are simple: relieve symptoms, improve quality of life, minimize adverse effects. Mild symptoms almost never need a hormone. Moderate-to-severe symptoms are where the branching starts.
Absolute:undiagnosed abnormal genital bleeding, known/suspected/history of breast cancer, known or suspected estrogen- or progesterone-dependent neoplasia, active or recent (within 1 year) VTE/PE or arterial thromboembolic disease (stroke, MI), liver dysfunction. Relative:elevated BP, hypertriglyceridemia, impaired liver function or past cholestatic jaundice, hypothyroidism, fluid retention, severe hypocalcemia, ovarian cancer, endometriosis, and exacerbation risk in asthma, diabetes, migraine, SLE, epilepsy, porphyria, hepatic hemangioma.
Oral and transdermal are used most and are considered equally effective for vasomotor symptoms, but they are notequally safe. Route matters more than most students expect.
| Form | Example (brand) | Typical starting / range |
|---|---|---|
| Oral (systemic) | ||
| Conjugated equine estrogens (CEE) | Premarin | 0.3–0.45 mg/day start, 0.3–1.25 mg/day range |
| Micronized 17β-estradiol | Estrace | 1 mg/day start, 1–2 mg/day range |
| Esterified estrogens | Menest | 0.3 mg/day start, up to 1.25 mg/day |
| Transdermal (systemic, preferred) | ||
| 17β-estradiol patch | Climara, Vivelle-Dot, Alora | 0.025–0.05 mg/day start (once or twice weekly patch), up to 0.1 mg/day |
| 17β-estradiol patch (osteoporosis only) | Menostar | 0.014 mg/day, once weekly |
| 17β-estradiol gel/emulsion/spray | EstroGel, Divigel, Estrasorb, Evamist | Delivers roughly 0.25–1 mg estradiol/day depending on product |
| Estradiol acetate vaginal ring (systemic) | Femring | 12.4 mg ring q3 months (delivers 0.05 or 0.1 mg/day) - only vaginal product that still needs a progestogen with a uterus |
| Intravaginal (local, low systemic exposure - urogenital symptoms only) | ||
| CEE vaginal cream | Premarin cream | 0.5–2 g/day, 21 days on/7 off |
| 17β-estradiol vaginal ring | Estring | 2 mg ring, replaced every 90 days |
| 17β-estradiol vaginal insert | Imvexxy | 4 or 10 mcg, twice weekly after a 2-week load |
| Estradiol hemihydrate vaginal tablet | Vagifem, Yuvafem | 10 mcg twice weekly after a 2-week load |
Oral estrogen goes through the liver first, which spikes hepatic protein synthesis, sex hormone-binding globulin, triglycerides, blood pressure, and C-reactive protein. Transdermal skips that first pass entirely, giving a more physiologic estradiol:estrone ratio and a measurably lower risk of VTE, stroke, breast tenderness, and gallbladder disease. The ESTHER trial quantified this directly: oral estrogen carried an odds ratio of 4.2for VTE versus 0.9for transdermal. If cost or insurance coverage isn't a barrier, transdermal estradiol should be the starting point for most patients, not oral CEE.
Adverse effects:nausea, headache, breast tenderness, heavy bleeding are common. More serious: increased risk of stroke, VTE, and gallbladder disease, all attenuated with the transdermal route. Lowest effective dose, shortest necessary durationis the rule; low-dose regimens (0.3–0.45 mg CEE, 0.5 mg micronized estradiol, 0.014–0.0375 mg transdermal) still control symptoms and bone loss with fewer side effects.
Anyone with an intact uterus taking systemic estrogen needs a progestogen (or the estrogen agonist/antagonist bazedoxifene) added, with one exception: low-dose local vaginal estrogen doesn't require it, because systemic exposure is too low to drive endometrial proliferation. Femring is the one vaginal product that doesneed a progestogen, since it's dosed for systemic effect.
| Progestogen | Cyclic dose (endometrial protection) |
|---|---|
| Medroxyprogesterone acetate (MPA) | 5–10 mg/day for 12–14 days/month |
| Micronized progesterone | 200 mg/day for 12–14 days/month |
| Norethindrone acetate | 5 mg/day for 12–14 days/month |
Medroxyprogesterone was the progestogen used in the Women's Health Initiative, and it's increasingly viewed as the driver of that trial's worst signals. The ESTHER trial found no increased VTE riskwith micronized progesterone or other pregnane-derivative progestins, but a roughly 4-fold increasein VTE with medroxyprogesterone specifically (OR ~3.9). It's also the progestogen most tied to the added breast cancer signal in combined therapy. Micronized progesterone (oral or per-vagina, which can reduce systemic side effects) or a levonorgestrel IUD are the preferred alternatives for endometrial protection today.
Adverse effects of progestogens:irritability, headache, mood swings, fluid retention, sleep disturbance (dosing at bedtime helps with the sedation from micronized progesterone). Most bothersome side effects on combined therapy trace back to the progestogen, not the estrogen, so switching agent or delivery route (oral → vaginal → IUD) is the usual fix before abandoning MHT altogether.
| Regimen | Brand(s) | Dose |
|---|---|---|
| Oral | ||
| CEE + medroxyprogesterone | Prempro (continuous), Premphase (continuous cyclic) | 0.625 mg CEE/2.5 or 5 mg MPA daily; low-dose 0.3–0.45 mg CEE/1.5 mg MPA |
| CEE + bazedoxifene | Duavee | 0.45 mg/20 mg daily (TSEC, no progestin needed) |
| Ethinyl estradiol + norethindrone acetate | Femhrt, Fyavolv | 2.5 mcg EE/0.5 mg NETA daily |
| Estradiol + drospirenone | Angeliq | 1 mg E/0.5 mg DRSP daily; low-dose 0.5/0.25 mg |
| Estradiol + norgestimate | Prefest | Intermittent: 1 mg E alone x3 days, then 1 mg E/0.09 mg norgestimate x3 days, repeating |
| Estradiol + norethindrone acetate | Activella, Mimvey, Amabelz | 1 mg E/0.5 mg NETA daily; low-dose 0.5/0.1 mg |
| Estradiol + progesterone | Bijuva | 1 mg E/100 mg micronized progesterone daily |
| Transdermal | ||
| Estradiol + norethindrone acetate patch | CombiPatch | 0.05/0.14 or 0.05/0.25 mg, applied twice weekly |
| Estradiol + levonorgestrel patch | Climara Pro | 0.045 mg E/0.015 mg LNG/day, once weekly |
You cannot talk about MHT without this trial. Before 2002, MHT was standard preventive care, roughly 38% of postmenopausal womenwere on it, prescribed for hyperlipidemia, cardiovascular disease, osteoporosis, and even Alzheimer prevention, largely on the strength of observational data.
| Feature | Detail |
|---|---|
| Sponsor / design | NIH-sponsored, randomized, multicenter |
| Population | 27,000 women, ages 50–79, average age 63(deliberately enriched for women without active vasomotor symptoms, to reduce unblinding bias) |
| Arms | With uterus: CEE + MPA ("HT") vs. placebo. Without uterus (prior hysterectomy): CEE alone ("ET") vs. placebo |
| Primary endpoint | Cardiovascular disease prevention and breast cancer incidence |
Result:stopped early at the midpoint analysis. The combined HT arm showed increasedCVD, stroke, VTE, and breast cancer relative to placebo, the opposite of what was expected. The estrogen-alone (ET) arm didn't show the CVD increase, still showed increased stroke and VTE, but showed a reduction (or at least no increase) in breast cancer. Both arms showed a benefit in colorectal cancer and hip fractures, and no difference in overall mortality.
The WHI population averaged 63 years old and was, on average, well over a decade past menopause. It was designed to test long-term chronic disease prevention in an older population, not symptom treatment in a newly menopausal one. Applying its risk numbers uncritically to a 48-year-old with hot flashes is the single biggest misapplication of this trial, and it's exactly why the field spent the next 20 years re-analyzing it by age.
A 2007 WHI sub-analysis of women under 60 found a 40% lower risk of MIand lower all-cause mortality with HT, essentially the opposite signal from the trial as a whole. Follow-up trials built specifically to test age:
| Trial | Design | Result |
|---|---|---|
| ELITE | Early (<6 yrs postmenopause) vs. late (>10 yrs) initiation of oral estradiol + vaginal progesterone | Significantly slower carotid plaque accumulation in the early group only |
| DOPS | Estradiol ± progestin vs. placebo, 10 years (stopped early due to WHI) | Lower MI, heart failure, and death; no increase in VTE, cancer, or stroke |
| KEEPS | Oral CEE + MP vs. transdermal E2 + MP vs. placebo, 4 years, ages 42–58 | No difference in carotid intima thickness between groups |
The net practice change: MHT is now recommended for most symptomatic women under 60, or within 10 years of menopause onset, especially those with premature or surgical menopause, where therapy is continued until the average natural age of menopause (about 51–52) purely to prevent the accelerated bone loss and cardiovascular risk that comes with losing estrogen early. Despite the cardioprotective signal in this window, the handbook is explicit: MHT should not be started or continued solely to prevent cardiovascular disease, that's a side benefit of treating symptoms in the right window, not an indication on its own.
Local, low-dose vaginal estrogen is a different risk category entirely. It's been shown safe for vulvovaginal symptoms even in patients with a history of breast cancer, and ACOG supports using it after other treatments fail, even in patients on tamoxifen. Don't withhold vaginal estrogen from a breast cancer survivor with vaginal dryness just because "estrogen is contraindicated," systemic and local exposure are not the same conversation.
For patients with a contraindication to estrogen, or who simply don't want hormones, several non-hormonal drug classes treat hot flashes, all technically off-label except one specific low-dose paroxetine product (Brisdelle).
| Drug | Dose | Notes |
|---|---|---|
| Venlafaxine | 37.5–75 mg/day | Considered first-line non-hormonal by many; SNRI |
| Desvenlafaxine | 50–100 mg/day | SNRI |
| Paroxetine (incl. Brisdelle) | 7.5–25 mg/day | Only paroxetine mesylate 7.5 mg (Brisdelle) is FDA-approved specifically for VMS |
| Citalopram / escitalopram | 10–20 mg/day | Citalopram has dose-dependent QTc prolongation |
| Clonidine patch | 0.1 mg/day | Effective, but sedation, dry mouth, and hypotension often limit use |
| Gabapentin | 300 mg at bedtime, up to 2400 mg/day divided | Good option when disrupted sleep + hot flashes coexist (dose in the evening) |
| Pregabalin | 75–150 mg BID | Similar niche to gabapentin |
Paroxetine, fluoxetine, and sertraline are strong CYP2D6 inhibitors and blunt the conversion of tamoxifen to its active metabolite, endoxifen. In a patient on tamoxifen for breast cancer who needs a non-hormonal option for hot flashes, venlafaxine is the safer choice, this is a frequently tested drug interaction.
Hot flashes are driven partly by neurokinin B signaling in the hypothalamic thermoregulatory center, and two drugs now target that directly instead of using an off-label antidepressant or antihypertensive:
Both are genuinely hormone-free, making them attractive for patients with a history of breast cancer or another absolute contraindication to estrogen.
Compounded, individually prepared hormone formulations (estrone, estradiol, estriol, progesterone, testosterone, DHEA, sometimes thyroid hormone) are marketed as "natural" but carry the same risk profileas FDA-approved products, without the FDA oversight on purity and dosing consistency. Reserve for a genuine unusual dosing need or an allergy to approved products, not as a default "safer" choice. Phytoestrogens and herbals (black cohosh, dong quai, red clover, ginseng) have weak estrogen receptor activity but insufficient dosing, safety, and efficacy data to recommend as an MHT substitute; common side effects are GI (constipation, bloating, nausea).
| Visit | What to check |
|---|---|
| 6-week follow-up | Symptom relief, adverse effects, and (if on cyclic/sequential therapy) the withdrawal bleeding pattern. Give MHT at least a full month before judging efficacy. |
| Annual visit | Medical history, physical and pelvic exam, blood pressure, routine endometrial cancer surveillance as indicated, annual mammogram scheduled to age/risk. |
| BMD | Measure in everyone ≥65, and in those younger with osteoporosis risk factors; repeat as clinically indicated. |
| Unexpected bleeding, sequential regimen | Bleeding outside the expected withdrawal window, or heavier/longer than usual → transvaginal ultrasound ± endometrial biopsy. |
| Unexpected bleeding, continuous-combined regimen | Irregular bleeding persisting >6 months after starting → endometrial evaluation. |
Persistent hot flashes on estrogen → increase the estrogen dose. Breast tenderness → reduce dose or switch to transdermal. Bloating or premenstrual-like symptoms → switch progestogen (or switch to bazedoxifene). Most side-effect-driven regimen changes are a dose or route tweak, not an automatic reason to stop MHT altogether.