About methenamine mandelate
Urinary antiseptic
Used for
- Prevention or suppression of recurrent urinary tract infections caused by susceptible bacteria
Usual adult dose
Usually 1 g four times daily; dosing depends on the product and kidney function.
Usual dose in children
Usually 25 mg/kg/day in four divided doses for children over six years; specialist guidance is important.
Common side effects
- Nausea, vomiting, or stomach upset
- Painful or frequent urination
- Rash or itching
Important warnings
- Not for treating kidney infection or severe urinary infection.
- Avoid with severe kidney or liver disease, dehydration, or metabolic acidosis.
- Urine must be acidic for effectiveness; avoid alkalinizing medicines unless directed.
- Long-term use may require monitoring.
Pregnancy
Safety is not well established; use only when a clinician considers it necessary.
Breastfeeding
Information is limited; discuss use with a clinician, especially when nursing a newborn.
Interactions
- Sulfonamide antibiotics can form insoluble crystals with methenamine; avoid combination.
- Urine-alkalinizing medicines, such as sodium bicarbonate, may reduce effectiveness.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.