Highlights for methenamine
methenamine Side Effects
Side effects that you should report to your doctor or health care professional as soon as possible:
- allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
- bladder pain, irritation
- dark urine
- lower back pain
- painful, frequent urination
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
- loss of appetite
- mouth sores
- stomach upset
methenamine May Interact with Other Medications
Do not take this medicine with any of the following medications:
- sulfa drugs
This medicine may also interact with the following medications:
- sodium bicarbonate
How to Use methenamine
Take this medicine by mouth with a full glass of water. Follow the directions on the prescription label. Do not crush or chew. Take your medicine at regular intervals. Do not take your medicine more often than directed. Take all of your medicine as directed even if you think you are better. Do not skip doses or stop your medicine early.
Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for children as young as 6 years old for selected conditions, precautions do apply.
They need to know if you have any of these conditions:
- kidney disease
- liver disease
- an unusual or allergic reaction to methenamine, tartrazine dye, other medicines, foods, dyes, or preservatives
- pregnant or trying to get pregnant
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.
Tell your doctor or health care professional if your symptoms do not improve or if you get new symptoms.
You will need to be on a special diet while taking this medicine. Ask your health care professional how many glasses of water or other fluids to drink each day. Also, ask which foods to include and which to avoid to help keep your urine acidic. Your urine must be acidic for this medicine to work.
Keep out of the reach of children.
Store between 15 and 30 degrees C (59 and 86 degrees F). Keep container tightly closed. Throw away any unused medicine after the expiration date.
Last Updated: June 25, 2009