Methenamine mandelate (By mouth)

Methenamine Mandelate (meth-EN-a-meen MAN-da-late)

Prevents and treats bacteria in urine caused by kidney infection, swelling of the bladder, and urinary tract infections.

Brand Name(s):

When This Medicine Should Not Be Used:

How to Use This Medicine:

Tablet

• Your doctor will tell you how much medicine to use. Do not use more than directed.
• Take this medicine after meals and at bedtime.
• Take all of the medicine in your prescription to clear up your infection, even if you feel better after the first few doses.
• Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Some medicines can affect how methenamine mandelate works. Tell your doctor if you are using salicylates, sulfamethizole, or sulfonamides.
• Do not drink milk or take antacids containing sodium carbonate or bicarbonate while you are using this medicine.

Warnings While Using This Medicine:

• Tell your doctor if you are pregnant or breastfeeding, or if you have gout.
• This medicine may cause bladder problems.
• Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.
• Call your doctor if your symptoms do not improve or if they get worse.
• Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Burning while urinating, painful or difficult urination

If you notice these less serious side effects, talk with your doctor:

• Nausea, stomach upset

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/4/2025