Urinary antiseptic
Methenamine hippurate
Brand names: Hiprex
Adult dose
Dose: 1g PO BD
Route: PO
Frequency: BD
Clinical pearls
- Recurrent UTI prophylaxis as alternative to long-term antibiotics (ALTAR trial supports non-inferiority)
- Requires acidic urine to release formaldehyde
Contraindications
- Severe hepatic impairment
- Severe renal impairment
- Metabolic acidosis
- Gout (caution — uric acid)
Side effects
- GI upset
- Rash
- Bladder irritation
Interactions
- Sulphonamides (precipitation)
- Urinary alkalinisers (reduce activity — needs acidic urine)
Monitoring
- U&E
- LFTs
Reference: BNF; NICE NG112; ALTAR trial; https://bnf.nice.org.uk/drugs/methenamine-hippurate/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators