Hydrolyzes to formaldehyde in acidic urine (pH < 6.0), which is bactericidal; requires urinary acidification to be effective
Dosing
Recurrent UTI prophylaxis (not acute treatment)
Max dose
1000 mg/dose; 3000 mg/day
Duration: Long-term prophylaxis; must maintain urine pH < 6.0
Recurrent UTI prophylaxis
Max dose
250 mg/dose; 750 mg/day
Duration: Long-term prophylaxis; maintain acidic urine
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →Safety
Absolute contraindications — do not use
Alkaline urine
Drug is ineffective at pH > 6.5
Concurrent urease-producing infections (Proteus, Staphylococcus)
These organisms alkalinize urine
Adverse effects
Serious
Bladder irritation
Hematuria (at high formaldehyde concentrations)
Urine pH (must remain < 6.0)Urine cultureRenal function
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →Interactions
No documented interactions.
Brands
India
Hexamine
Leeford Healthcare
FAQs
Frequently asked questions
›What is Methenamine (Hexamine)?
Methenamine (Hexamine) is a urinary antiseptic used in pets. Hydrolyzes to formaldehyde in acidic urine (pH < 6.0), which is bactericidal; requires urinary acidification to be effective
›What is Methenamine (Hexamine) used for in pets?
Methenamine (Hexamine) is used in veterinary medicine for: Recurrent UTI prophylaxis (not acute treatment); Recurrent UTI prophylaxis.
›What is the Methenamine (Hexamine) dose for dogs?
For dogs, Methenamine (Hexamine) is typically dosed as follows — Recurrent UTI prophylaxis (not acute treatment): 10–20 mg/kg PO TID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Methenamine (Hexamine) dose for cats?
For cats, Methenamine (Hexamine) is typically dosed as follows — Recurrent UTI prophylaxis: 10–20 mg/kg PO TID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Methenamine (Hexamine)?
Common: GI irritation, Nausea. Serious (call your vet immediately): Bladder irritation, Hematuria (at high formaldehyde concentrations).
›Does Methenamine (Hexamine) need a prescription?
Yes. Methenamine (Hexamine) is a prescription medication and should only be administered under veterinary supervision.
›When should Methenamine (Hexamine) not be used?
Do not use Methenamine (Hexamine) if: Renal insufficiency.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →References
References
The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.
Textbooks & handbooks — 5
- Plumb's Veterinary Drug Handbook
- Withrow & MacEwen's Small Animal Clinical Oncology
- Merck Veterinary Manual
- NRC Nutrient Requirements of Dogs and Cats
- Veterinary Pharmacology and Therapeutics (Riviere & Papich)
Clinical guidelines & consensus — 4
- ASPCA Animal Poison Control Center Guidelines
- AAHA Diabetes Management Guidelines
- ASPCA Poison Control Guidelines
- RECOVER CPR Guidelines
Journals & peer-reviewed studies — 2
- EPIC Study (J Vet Intern Med 2016)
- JVIM FAT CAT Study
Regulatory & approvals — 1
- CDSCO Veterinary Drug Approval Registry (1969–2026)
Databases — 1
- Washington State University VCPL MDR1 Database