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Mandelamine Side Effects

Generic name: methenamine

Medically reviewed by Last updated on Dec 17, 2020.

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

For the Consumer

Applies to methenamine: oral tablet

Side effects requiring immediate medical attention

Along with its needed effects, methenamine (the active ingredient contained in Mandelamine) 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


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

Side effects not requiring immediate medical attention

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

For Healthcare Professionals

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


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]


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

Frequency not reported: Generalized skin rash[Ref]


Uncommon (0.1% to 1%): Gastric irritation

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


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]


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


Frequency not reported: Hypersensitivity reactions[Ref]


Frequency not reported: Anorexia


Frequency not reported: Anterior uveitis[Ref]


1. "Product Information. Hiprex (methenamine)." Hoechst Marion-Roussel Inc, Kansas City, MO.

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

4. Gleckman R, Alvarez S, Joubert D, Matthews S "Drug therapy reviews: methenamine mandelate and methenamine hippurate." Am J Hosp Pharm 36 (1979): 1509-12

5. "Product Information. Mandelamine (methenamine)." Parke-Davis, Morris Plains, NJ.

6. Australian Drug Evaluation Committee "Adverse effects of drugs commonly used in the treatment of urinary tract infection." Med J Aust 1 (1972): 435-8

7. Brumfitt W, Hamilton-Miller J, Gargan R, Cooper J, Smith GW "Long-term prophylaxis of urinary infections in women: comparative trial of trimethoprim, methenamine hippurate and topical povidone-iodine." J Urol 130 (1983): 1110-4

8. Brumfitt W, Cooper J, Hamilton-Miller J "Prevention of recurrent urinary infections in women: a comparative trial between nitrofurantoin and methenamine hippurate." J Urol 126 (1981): 71-4

9. Kolker RJ "Medication-induced bilateral anterior uveitis." Arch Ophthalmol 109 (1991): 1343

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.