Methenamine (By mouth)

There may be other brand names for this medicine.

You should not use this medicine if you have ever had an allergic reaction to methenamine or tartrazine.

Your doctor will tell you how much medicine to use and how often. Do not use more medicine or use it more often than your doctor tells you to.
Drink plenty of water or cranberry juice every day while you are using this medicine.
Keep using this medicine for the full time treatment time. If you stop using this medicine too soon, your infection may come back.
Swallow the tablet or coated tablet whole with a full glass of water. Do not chew, crush, or break it.
Measure the oral liquid with a measuring spoon or dropper. Shake the bottle before using. Take with a full glass of water or with food.
Empty the granules into a full glass of water and let them dissolve before you drink the mixture.

Take the missed dose as soon as possible.
If it is almost time for your next regular dose, wait until then to take the medicine and skip the missed dose.
You should not use two doses at the same time.

Store in the original tightly closed, light-resistant container, away from moisture and direct light. Do not freeze.
Keep all medicine away from the reach of children.

Make sure your doctor knows if you are also using a sulfa drug (such as Bactrim® or Septra®).
It is best to avoid using antacids (such as Maalox® or Mylanta®) while taking methenamine.
This medicine works best in acidic urine. Drinking cranberry juice will help keep urine acidic. Avoid foods that lower the acid in your urine, such as nuts or milk and other dairy products.

Check with your doctor before using this medicine if you have liver or kidney problems, severe dehydration, or other medical problems.
If you are pregnant or breastfeeding, talk to your doctor before taking this medicine

Last Updated: 1/27/2017