Alpha-1 Blocker
Pregnancy: C
Doxazosin (BPH)
Brand names: Cardura
Adult dose
Dose: 1 mg at night initially, titrate to 4–8 mg once daily
Route: oral
Frequency: once daily
Max: 8 mg/day (BPH); 16 mg/day (hypertension)
Start 1 mg at bedtime to minimise first-dose hypotension; titrate at 1–2 week intervals; XL formulation reduces postural hypotension
Paediatric dose
Route:
Not licensed for BPH in children
Dose adjustments
Renal
No dose adjustment required
Hepatic
Use with caution in hepatic impairment
Clinical pearls
- Dual benefit for BPH patients with coexistent hypertension
- First-dose syncope risk — always start 1 mg at night
- Intraoperative floppy iris syndrome: inform ophthalmologist before cataract surgery — cannot be reversed once started
Contraindications
- History of orthostatic hypotension
- Monotherapy in overflow incontinence
- Intraoperative floppy iris syndrome (risk — warn ophthalmologist)
Side effects
- Orthostatic hypotension (especially first dose)
- Dizziness
- Headache
- Fatigue
- Palpitations
- Oedema
Interactions
- Antihypertensives (additive hypotension)
- PDE5 inhibitors (severe hypotension)
- NSAIDs (reduce antihypertensive effect)
Monitoring
- Blood pressure (standing and lying)
- IPSS scores
Reference: BNFc; BNF 86; NICE NG97. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators