Methenamine is a urinary antiinfective medicine. Methenamine fights bacteria in the urine and bladder.

Methenamine may be used to treat and prevent urinary tract infections.

Methenamine may also be used for purposes other than those listed here.

Take all of the methenamine that has been prescribed for you even if you begin to feel better. Symptoms may start to improve before the infection is completely treated.

Take each dose with a full glass of water. Plenty of fluid should be consumed while taking methenamine.

Your healthcare provider may recommend drinking additional water and/or certain fruit juices (e.g., cranberry, plum, prune) and increased protein in the diet while taking methenamine to ensure adequate hydration and acidity of the urine. It may also be recommended to avoid citrus fruits and juices (e.g., orange, grapefruit, lemon), milk and dairy products, and antacids during treatment with methenamine. These products may decrease the effectiveness of methenamine. Follow your healthcare provider's instructions.

Before taking methenamine, talk to your doctor if you

• have liver problems;

• have kidney problems;

• have other medical conditions; or

• take other medications.

You may not be able to take methenamine, or you may require a dosage adjustment or special monitoring during treatment.

Methenamine is in the FDA pregnancy category C. This means that it is not known whether it will be harmful to an unborn baby. Do not take methenamine without first talking to your doctor if you are pregnant or could become pregnant during treatment.

Methenamine passes into breast milk and may affect a nursing baby. Do not take methenamine without first talking to your doctor if you are breast-feeding a baby.