Methenamine is used to prevent or control returning urinary tract infections caused by certain bacteria. It is not used to treat an active infection. Antibiotics must be used first to treat and cure the infection. Methenamine is a drug that stops the growth of bacteria in urine. This medication also contains an ingredient that helps to make the urine acidic. When the urine is acidic, methenamine turns into formaldehyde to kill the bacteria.This drug is effective only against bacterial infections in the urinary tract. It will not work for other types of bacterial infections (such as in the blood) or for viral infections (such as the common cold or flu). Unnecessary use or misuse of any antibacterial drug can lead to its decreased effectiveness.
How to use
Take this medication by mouth as directed by your doctor. Dosage is based on the brand of methenamine you are prescribed, your medical condition, and your response to treatment. For children, dosage is also based on age and weight.
Methenamine works better if your urine is more acidic. Your doctor may test the acidity of your urine (urine pH). If necessary, your doctor may recommend ways to increase urine acidity (such as by taking vitamin C/drinking cranberry juice, limiting foods that decrease acidity/increase alkalinity such as milk products/most fruits, adjusting alkalinizing medications). See also Drug Interactions section. Follow your doctor's instructions.
For the best effect, take this drug at evenly spaced times. To help you remember, take this medication at the same time(s) every day.
Keep taking this medication for the full time prescribed, even if you feel well. Skipping doses or stopping the medication too early may allow bacteria to continue to grow, which may result in a return of the infection and make the bacteria more difficult to treat (resistant). Do not take more of this drug than directed because it may increase your chance of side effects.
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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.