Note: This document contains side effect information about methenamine. Some dosage forms listed on this page may not apply to the brand name Hiprex.

Applies to methenamine: oral tablet.

Serious side effects of Hiprex

Along with its needed effects, methenamine (the active ingredient contained in Hiprex) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking methenamine:

Less common

• Skin rash

Rare

• Blood in urine
• lower back pain
• pain or burning while urinating

Other side effects of Hiprex

Some side effects of methenamine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

• Nausea and vomiting

For Healthcare Professionals

Applies to methenamine: compounding powder, oral suspension, oral tablet.

General

This drug was generally well tolerated. Minor side effects have been reported in less than 3.5% of patients and were reversible when the drug was stopped.^[Ref]

Dermatologic

Uncommon (0.1% to 1%): Rash, pruritus

Frequency not reported: Generalized skin rash^[Ref]

Gastrointestinal

Uncommon (0.1% to 1%): Gastric irritation

Frequency not reported: Nausea, vomiting, upset stomach, stomatitis, gastrointestinal disturbances, diarrhea, abdominal cramping^[Ref]

Genitourinary

High doses have been associated with albuminuria, gross hematuria, bladder irritation, and painful/frequent micturition.^[Ref]

Uncommon (0.1% to 1%): Bladder irritation

Frequency not reported: Dysuria, hematuria, urinary frequency, albuminuria^[Ref]

Hepatic

Frequency not reported: Elevated AST, elevated ALT^[Ref]

Hypersensitivity

Frequency not reported: Hypersensitivity reactions^[Ref]

Metabolic

Frequency not reported: Anorexia

Ocular

Frequency not reported: Anterior uveitis^[Ref]