Non-steroidal aromatase inhibitor
Letrozole
Brand names: Femara
Adult dose
Dose: Breast cancer: 2.5mg PO OD. Anovulatory infertility (off-label, NICE-supported): 2.5mg PO OD on days 2–6 of cycle
Route: PO
Frequency: OD
Clinical pearls
- Postmenopausal ER+ breast cancer
- NICE-recommended over clomifene for ovulation induction in PCOS (NG3)
Contraindications
- Premenopausal women (oncology indication)
- Pregnancy
- Hypersensitivity
Side effects
- Hot flushes
- Arthralgia
- Osteoporosis/fractures
- Fatigue
- Hypercholesterolaemia
Interactions
- Tamoxifen (avoid — reduced letrozole)
- Oestrogen-containing products
Monitoring
- Bone density
- Lipids
- LFTs
Reference: BNF; NICE TA112/NG3; https://bnf.nice.org.uk/drugs/letrozole/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- SMART Risk Score for Recurrent CVD · Cardiovascular Risk
- PCSK9 Inhibitor Eligibility Assessment · Lipid Management
- Immune-Related Adverse Events (irAE) -- GI Toxicity Colitis Grading · Oncology-Related GI
- irAE Hepatitis Grading (CTCAE) · Immunotherapy
- DIPSS — Dynamic International Prognostic Scoring System for Myelofibrosis · Cancer Prognosis
- BALL Score for Relapsed/Refractory CLL · Leukaemia
Pathways
- Acute Myeloid Leukaemia Presentation · BSH; NICE — NG146
- Tumour Lysis Syndrome · Cairo-Bishop; BSH; NICE — Best Practice
- Diabetic Ketoacidosis (DKA) · JBDS 2013 / Joint British Diabetes Societies; NICE NG17
- Adult Hypoglycaemia (Treated Diabetes) · JBDS-IP (2023): Hospital Management of Hypoglycaemia
- Adrenal Crisis · Society for Endocrinology Emergency Guidance (2024)
- Type 2 Diabetes Management · NICE NG28 2022