Methenamine

  • Brand Name : Hiprex
  • Drug Class : Antibiotics, Other
  • Medical Author : Nazneen Memon, BHMS, PGDCR
  • Medical Reviewer : Divya Jacob, Pharm. D.
  • _eael_post_view_count : 14

What Is Methenamine and How Does It Work?

Methenamine is a prescription medicine used for the prevention and treatment of urinary tract infections.

  • Methenamine is available under the following different brand names: Hiprex, Urex

What Are Dosages of Methenamine?

Adult and pediatric dosage

Oral solution

  • 500 mg/5mL

Tablet, hippurate

  • 1g

Tablet, mandelate

  • 500mg
  • 1g

Urinary Tract Infection Prophylaxis

Adult dosage

  • Methenamine hippurate: 1 g orally every 12 hours
  • Methenamine mandelate: 1 g orally every 6 hours

Pediatric dosage

Methenamine hippurate

  • Children below 6 years: Safety and efficacy not established
  • Children between 6 to 12 years: 0.5-1 g orally every 12 hours
  • Children above 12 years: 1 g orally every 12 hours

Methenamine mandelate

  • Children below 6 years: 18.4 mg/kg orally every 6 hours
  • Children between 6 to 12 years: 0.5-1 g orally every 6 hours
  • Children above 12 years: 1 g orally every 6 hours

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Methenamine?

Common side effects of Methenamine include:

  • nausea,
  • vomiting,
  • upset stomach,
  • diarrhea,
  • abdominal cramps,
  • painful or difficult urination,
  • loss of appetite, and
  • skin rash.

Serious side effects of Methenamine include:

  • increased urination,
  • painful urination,
  • blood in urine,
  • swelling, and
  • shortness of breath.

Rare side effects of Methenamine include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

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