Aromatase inhibitor (AI)also: anastrozole, letrozole, exemestane: A class of drug used after some breast cancers (anastrozole, letrozole, exemestane) that blocks the body's ability to make estrogen from other hormones. Highly effective for the cancer; the side-effect profile is essentially induced menopause, often with severe vasomotor and joint symptoms.

B

Bioidentical hormonesalso: body-identical, compounded bioidenticals: 'Bioidentical' is a marketing term, not a regulatory one. Two very different things hide under it: regulated body-identical MHT (transdermal estradiol, micronized progesterone), which is well-studied and prescribable; and compounded 'bioidenticals' from private pharmacies, which aren't dose-tested batch by batch and not licensed. The two are routinely conflated.

C

CBT-Ialso: cognitive behavioural therapy for insomnia: Cognitive Behavioural Therapy for Insomnia. A short, structured therapy (usually 4-8 sessions) that has stronger evidence for menopausal sleep than most sleep medications. Available in person, via apps, and on the NHS via referral.

D

DEXA scanalso: DXA, bone density scan: A low-dose X-ray that measures bone mineral density at the hip and spine. The standard tool for diagnosing osteopenia and osteoporosis. Usually offered after age 65, or earlier if you have risk factors (early menopause, family history, fragility fracture, AI therapy).

E

Estradiolalso: E2, 17-beta estradiol: The main estrogen the ovary makes during your reproductive years. It's also the active ingredient in body-identical MHT, delivered as a patch, gel, spray or tablet. Levels drop and then bottom out across perimenopause and menopause.

F

Fezolinetantalso: Veozah, Veoza, NK3 antagonist: A non-hormonal prescription drug (brand names Veozah / Veoza) that blocks the brain pathway responsible for hot flashes. Approved in the US, UK, EU and Canada. A real option for people who can't or won't take MHT, including many breast cancer survivors.
FSHalso: follicle-stimulating hormone: A pituitary hormone that rises as the ovaries become less responsive. A high FSH can support a menopause diagnosis but a single reading isn't reliable in perimenopause; FSH swings wildly. Most current guidelines say diagnosis is clinical (symptoms + age + cycle pattern), not bloodwork.

G

GSMalso: genitourinary syndrome of menopause, vaginal atrophy, vulvovaginal atrophy: Genitourinary Syndrome of Menopause. The umbrella term for the changes estrogen loss causes in the vulva, vagina, urethra and bladder: dryness, itching, painful sex, recurrent UTIs, urgency. Doesn't go away on its own; vaginal estrogen is first-line and suitable for many people after a review of symptoms and medical history.

H

HRT / MHTalso: MHT, HRT, MHT / HRT, hormone replacement therapy, menopausal hormone therapy, menopause hormone therapy: Menopausal hormone therapy (MHT), often called HRT, treats menopause symptoms. Systemic treatment uses estrogen, with a progestogen usually added if you have a uterus to protect its lining; it can also help prevent bone loss. Low-dose local vaginal estrogen is a separate treatment for genital and urinary symptoms. HRT is still a common name, particularly in the UK.
Hot flash / flushalso: vasomotor symptom, VMS, night sweats: A sudden wave of heat, often with sweating and a racing heart, lasting seconds to minutes. The most common menopausal symptom; for most women it lasts 7-10 years on average, longer than older estimates suggested. The medical label 'vasomotor symptoms' (VMS) covers both day flushes and night sweats.
Hysterectomy: Surgical removal of the uterus. If the ovaries are left in place, it doesn't itself cause menopause, though ovarian function can decline earlier afterward. If ovaries are also removed (oophorectomy), you go into surgical menopause overnight.

I

IUS (Mirena)also: levonorgestrel-releasing IUS, hormonal coil: A small T-shaped device placed in the uterus that slowly releases levonorgestrel (a progestogen). In perimenopause it manages heavy bleeding and provides the progesterone half of MHT for people using estrogen, all from one device. Lasts five to eight years depending on indication.

L

Local / vaginal estrogenalso: topical estrogen, Vagifem, Estring, Imvexxy: A very low dose of estrogen applied directly to the vagina (cream, tablet, ring, insert). Treats GSM with minimal absorption into the bloodstream. May be an option when systemic MHT isn't suitable. After breast cancer, discuss symptoms, cancer treatment and the benefits and risks with your doctor or specialist.

M

Menopause: Defined as 12 consecutive months without a period, retrospectively. The day after that 12-month mark is your one day of being 'in menopause'; everything after is postmenopause. Average age is 51 (UK/US/Canada); anything before 45 is early menopause, before 40 is premature.
Micronized progesteronealso: Utrogestan, Prometrium: Body-identical progesterone in a capsule, typically taken at night (it's mildly sedating, which most people appreciate). The progesterone half of body-identical MHT, used to protect the uterine lining when you're taking estrogen.

N

NAMS / The Menopause Societyalso: MSCP, menopause certified practitioner: The Menopause Society (formerly NAMS, the North American Menopause Society) is the largest professional body for menopause doctors or specialists in North America. The MSCP credential (Menopause Society Certified Practitioner) signals formal training; you can search their public directory.

O

Oophorectomyalso: ovariectomy, BSO (bilateral salpingo-oophorectomy): Surgical removal of one or both ovaries. Bilateral (both ovaries) means immediate, permanent menopause regardless of age. Common reasons include cancer treatment, BRCA risk reduction, severe endometriosis, and persistent ovarian cysts.
Osteopenia / Osteoporosis: Lower-than-normal bone density (osteopenia) and significantly low bone density with fracture risk (osteoporosis). Estrogen loss accelerates bone loss in the years immediately after menopause, which is why bone is one of the long-term reasons MHT is offered. Diagnosed by DEXA scan.

P

Perimenopause: The transition years leading up to menopause, when hormones swing erratically and symptoms typically begin. Can last 4-10 years; most women enter it in their early-to-mid 40s. Periods are still happening, often irregularly. This is when most symptom care actually lives.
PCOS / PMOSalso: polycystic ovary syndrome, polyendocrine metabolic ovarian syndrome, PCOS, PMOS: A common hormonal-metabolic condition (around 1 in 8 women) marked by some combination of irregular cycles, higher androgens, and insulin resistance. In 2026 a Lancet-published international consensus, led by Helena Teede at Monash, proposed renaming PCOS to PMOS — polyendocrine metabolic ovarian syndrome — to reflect that it's a multisystem hormonal and metabolic condition, not primarily a gynecological one. Both names refer to the same condition; you'll see both in clinics for some years. A PCOS/PMOS history matters in perimenopause because it shifts the metabolic, mood and sleep picture, and it changes which treatments tend to land well.
POIalso: primary ovarian insufficiency, premature ovarian failure: Primary Ovarian Insufficiency: menopause before age 40. Different physiology, different long-term risk picture (bone, cardiovascular, cognitive), and different treatment defaults than typical menopause. MHT until at least age 51 is the standard recommendation.
Postmenopause: The phase after the 12-months-no-period mark. The hormonal turbulence of perimenopause has passed, but symptoms can persist for years and the long-term considerations (bone, cardiovascular, GSM) move to the foreground.
Premature menopause: Menopause before age 40 from any cause (POI, surgery, chemo, radiation). Carries higher long-term risks than typical menopause and is treated as a different clinical situation: MHT until the average age of menopause is the default unless contraindicated.
Progestogen / Progestin: Umbrella term for progesterone-like compounds. 'Progesterone' usually means the body-identical (micronized) form; 'progestins' usually means synthetic versions (medroxyprogesterone acetate, norethisterone, levonorgestrel). They behave differently in the body; the synthetic-progestin breast cancer signal in WHI doesn't translate cleanly to micronized progesterone.

S

SERMalso: selective estrogen receptor modulator, tamoxifen, raloxifene, ospemifene: Selective Estrogen Receptor Modulators: drugs that act like estrogen in some tissues and block it in others. Tamoxifen (breast cancer), raloxifene (osteoporosis), ospemifene (painful sex from GSM). The selectivity is why they have such different use cases.
SSRI / SNRI: Antidepressant classes (selective serotonin reuptake inhibitors / serotonin-norepinephrine reuptake inhibitors) that, at low doses, also reduce hot flashes. Useful when MHT isn't an option or when mood symptoms are also present. Paroxetine, venlafaxine and escitalopram have the best vasomotor evidence.
Surgical menopause: Menopause caused by removal of both ovaries, regardless of age. Symptoms typically begin within days and are often severe because there's no taper. Bone, cardiovascular and cognitive risks are higher than for natural menopause at the same age.

T

Tamoxifen: A SERM used for many estrogen-receptor-positive breast cancers, typically for 5-10 years. Blocks estrogen at breast tissue but acts like estrogen elsewhere. Side effects often mimic menopause: hot flashes, joint pain, mood shifts, GSM. MHT is generally not offered alongside it; the non-hormonal toolkit is.
Testosterone in menopause carealso: Testosterone (in women), testosterone: Ovaries and adrenal glands contribute to testosterone production. Levels vary with age and hormone history; menopause isn't a sharp testosterone cliff. The current evidence supports testosterone for HSDD (low desire causing distress) in postmenopausal women, off-label in most countries. Not licensed for energy, mood or 'wellbeing' alone, despite the marketing.
Transdermal: Through the skin. Transdermal MHT (patches, gels, sprays) avoids the first-pass through the liver and carries less clotting risk than oral estrogen, which is why it's often the preferred route, especially for people with migraine, clotting risk, or higher BMI.

V

Vaginal atrophy: Older term for the vaginal changes of GSM (thinning, dryness, loss of elasticity). The newer 'GSM' label is preferred because the bladder and urethra are affected too, not just the vagina. Same condition, broader frame.
VMSalso: vasomotor symptoms: Vasomotor Symptoms: the umbrella medical label for hot flashes and night sweats. The thing trials measure when they say 'reduced VMS by X%'.

W

WHIalso: Women's Health Initiative: The 2002 trial whose press conference reshaped a generation's view of HRT. Tested one specific combination (conjugated equine estrogen + medroxyprogesterone) in women whose average age was 63. The headline 'HRT causes cancer' didn't survive re-analysis, but the public messaging never caught up.

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