Methenamine Mandelate
Tablet, Film Coated · Oral
Uses
Methenamine mandelate, USP is indicated for the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic urinary tract infections; also for infected residual urine sometimes accompanying neurologic diseases. When used as recommended, methenamine mandelate, USP is particularly suitable for long-term therapy because of its safety and because resistance to the nonspecific bactericidal action of formaldehyde does not develop. Pathogens resistant to other antibacterial agents may respond to methenamine mandelate, USP because of the nonspecific effect of formaldehyde formed in an acid urine. Prophylactic Use Rationale: Urine is a good culture medium for many urinary pathogens. Inoculation by a few organisms (relapse or reinfection) may lead to bacteriuria in susceptible individuals. Thus, the rationale of management in recurring urinary tract infection (bacteriuria) is to change the urine from a growth-supporting to a growth-inhibiting medium. There is a growing body of evidence that long-term administration of methenamine mandelate, USP can prevent the recurrence of bacteriuria in patients with chronic pyelonephritis. T herapeutic Use Rationale: Methenamine mandelate, USP helps to sterilize the urine, and in some situations in which underlying pathologic conditions prevent sterilization by any means, it can help to suppress the bacteriuria. Methenamine mandelate, USP should not be used alone for acute infections with parenchymal involvement causing systemic symptoms such as chi ls and fever. A thorough diagnostic investigation as a part of the overall management of the urinary tract infection should accompany the use of methenamine mandelate, USP.
Dosage and administration
The average adult dose is 4 g daily given as 2 teaspoon after each meal and at bedtime. Children 6 to 12 should receive half the adult dose, and children under 6 years of age should receive 250 mg per 30 lb body weight, four times daily. Since an acid urine is essential for antibacterial activity, with maximum efficacy occurring at pH 5.5 or below, restriction of alkalinizing foods and medication is thus desirable. If testing of urine pH reveals the need, supplemental acidification should be given.
Contraindications
Contraindicated in renal insufficiency. Methenamine mandelate, USP should not be used in patients who have previously exhibited hypersensitivity to it.
Precautions
Dysuria may occur (usually at higher than recommended dosage). This can be controlled by reducing the dosage and the acidification. When urine acidification is contraindicated or unattainable (as with some urea-splitting bacteria), the drug is not recommended.
Side effects
An occasional patient may experience gastrointestinal disturbance or a generalized skin rash. Microscopic and rarely gross hematuria have been described.
Drug interactions
Formaldehyde and sulfamethizole form an insoluble precipitate in acid urine; therefore, methenamine mandelate, USP should not be administered concurrently with sulfamethizole.
Pregnancy
Pregnancy Category C: Animal reproduction studies have not been conducted with methenamine mandelate, USP. It is also not known whether methenamine mandelate, USP can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Methenamine mandelate, USP should be given to a pregnant woman only if clearly needed. Since introduction, published reports on the use of methenamine mandelate, USP in pregnant women have not shown an increased risk of fetal abnormalities from use during pregnancy.
Description
Methenamine mandelate, USP, a urinary antibacterial agent, is the chemical combination of mandelic acid with methenamine. Methenamine mandelate, USP is available for oral use as oral liquid. Each 5 mL (teaspoon) contains 500 mg Methenamine Mandelate. The oral solution also contains Sodium Saccharine, Benzyl Alcohol, Xanthan Gum, Mixed Berry Flavor and Water for Injection.
How supplied
Methenamine Mandelate Oral Solution, 500 mg/5 mL, is a clear solution and available in the following oral dosage forms: NDC 85477-115-16: 16 fl oz (473 mL) bottle Store at controlled room temperature between 20°-25°C (68°-77°F); excursions permitted to 15°-30°C (59°-86°F) [See USP controlled Room Temperature]. Dispense in a tight, light-resistant container as defined in the USP.
Label text from the FDA structured product label by Oncora Pharma, LLC (revised Apr 17, 2026). Long sections are shortened; the complete label is on DailyMed.
Active ingredients
- Methenamine Mandelate in 9 products
Methenamine Mandelate NDC products (9)
| NDC | Strength & form | Labeler | Type |
|---|---|---|---|
| 72162-2654 | Methenamine Mandelate 500 mg/1 Tablet, Film Coated | Bryant Ranch Prepack | UNAPPROVED DRUG OTHER |
| 72162-2655 | Methenamine Mandelate 1000 mg/1 Tablet, Film Coated | Bryant Ranch Prepack | UNAPPROVED DRUG OTHER |
| 62135-200 | Methenamine Mandelate 500 mg/1 Tablet, Film Coated | Chartwell RX, LLC | UNAPPROVED DRUG OTHER |
| 62135-201 | Methenamine Mandelate 1000 mg/1 Tablet, Film Coated | Chartwell RX, LLC | UNAPPROVED DRUG OTHER |
| 42799-105 | Methenamine Mandelate 500 mg/1 Tablet | Edenbridge Pharmaceuticals LLC. | UNAPPROVED DRUG OTHER |
| 42799-106 | Methenamine Mandelate 1000 mg/1 Tablet | Edenbridge Pharmaceuticals LLC. | UNAPPROVED DRUG OTHER |
| 85477-115 | Methenamine Mandelate 500 mg/5mL Solution | Oncora Pharma, LLC | UNAPPROVED DRUG OTHER |
| 69367-436 | Methenamine Mandelate 500 mg/1 Tablet, Film Coated | Westminster Pharmaceuticals, LLC | UNAPPROVED DRUG OTHER |
| 69367-437 | Methenamine Mandelate 1000 mg/1 Tablet, Film Coated | Westminster Pharmaceuticals, LLC | UNAPPROVED DRUG OTHER |
Frequently asked questions
What is Methenamine Mandelate used for?
Methenamine mandelate, USP is indicated for the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic urinary tract infections; also for infected residual urine sometimes accompanying neurologic diseases. When used as recommended, methenamine mandelate, USP is particularly suitable for long-term therapy because of its safety and because resistance…
What are the side effects of Methenamine Mandelate?
An occasional patient may experience gastrointestinal disturbance or a generalized skin rash. Microscopic and rarely gross hematuria have been described. See the full label for the complete list.
Who makes Methenamine Mandelate?
Methenamine Mandelate is listed by 5 labelers in the FDA NDC directory, including Bryant Ranch Prepack, Chartwell RX, LLC, Edenbridge Pharmaceuticals LLC., Oncora Pharma, LLC.