Pharmacology · Selective oestrogen receptor modulators (SERMs)
Raloxifene !
A tablet for postmenopausal osteoporosis that acts like oestrogen on bone but not on the uterus. It also lowers breast cancer risk but raises clot risk.
Updated 2026-11-01
The figure shows raloxifene bound to the ligand-binding domain of human ERα.
Mechanism of action
Raloxifene binds the oestrogen receptor and acts as an agonist in bone, where it slows resorption and preserves bone mineral density. In the breast and the endometrium it acts as an antagonist, so it lowers the risk of invasive receptor-positive breast cancer without stimulating the uterus.
- Binds the oestrogen receptor
- Bone: acts like oestrogen and slows resorption
- Breast: blocks oestrogen and lowers cancer risk
- Endometrium: no stimulation
Pharmacokinetics
- Absorption
- Well absorbed by mouth but extensively metabolised on first pass, so little reaches the blood unchanged
- Distribution
- Highly bound to plasma proteins
- Metabolism
- Glucuronidated in the liver and gut, with enterohepatic recycling
- Elimination
- Mainly in the faeces
- Half-life
- About 28 hours, prolonged by enterohepatic cycling
Indications
- Treatment and prevention of osteoporosis in postmenopausal women Osteoporosis →
- Reduction of the risk of invasive breast cancer in postmenopausal women with osteoporosis or at high risk Breast cancer →
Adverse effects
Common
- Hot flashes
- Leg cramps
- Swelling of hands, feet or ankles
- Flu-like symptoms
- Joint pain
Contraindications
- Active or past venous thromboembolism, including deep vein thrombosis, pulmonary embolism and retinal vein thrombosis
- Pregnancy
Key interactions
- Cholestyramine and other anion-exchange resins
- Reduce absorption and enterohepatic cycling of raloxifene; not used together.
- Warfarin
- Prothrombin time is monitored when raloxifene is started or stopped.
- Systemic oestrogens
- Not studied together and not recommended.
What is monitored
- Signs of venous thromboembolism
- Bone mineral density
- Breast examination and mammography as usual
Administration and safety
- Oral tablet once a day, with or without food.
- It does not treat hot flashes; it may make them worse.
Nursing care
- Ask about any past deep vein thrombosis, pulmonary embolism or retinal vein thrombosis before starting.
- Teach clot warning signs and the need to avoid long immobility; stop before planned immobilisation as the team decides.
- Explain that hot flashes and leg cramps are common.
- Encourage calcium, vitamin D and exercise for bone health.
Pregnancy and breastfeeding
Contraindicated in pregnancy; it is meant only for postmenopausal women.
Test yourself
Think of the answer, then tap the question to see it.
Why does raloxifene not raise endometrial cancer risk the way tamoxifen does?
Raloxifene does not stimulate the endometrium, while tamoxifen is a partial agonist there.
Which past history rules out raloxifene?
Active or past venous thromboembolism: deep vein thrombosis, pulmonary embolism or retinal vein thrombosis.
Why is cholestyramine not given with raloxifene?
It binds raloxifene in the gut and interrupts its enterohepatic recycling, lowering its absorption.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Raloxifene: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2018); DailyMed - RALOXIFENE HYDROCHLORIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2024); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); HUMAN ESTROGEN RECEPTOR LIGAND-BINDING DOMAIN IN COMPLEX WITH RALOXIFENE (RCSB Protein Data Bank, 1998).
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Representative model, for educational purposes only.