What is Methenamine?
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.
What is the most important information I should know about Methenamine?
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.
What should I discuss with my healthcare provider before taking Methenamine?
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.
Methenamine Side Effects
What are the possible side effects of Methenamine?
If you experience any of the following serious side effects, stop taking methenamine and seek emergency medical attention or contact your doctor immediately:
- an allergic reaction (shortness of breath; closing of the throat; swelling of the lips, face, or tongue; or hives
- lower back or side pain
- blood in urine; or
- increasingly painful or difficult urination
Other, less serious side effects may be more likely to occur. Continue to take methenamine and talk to your doctor if you experience
- nausea or upset stomach
- decreased appetite; or
- skin rash
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome. You may report side effects to FDA at 1-800-FDA-1088.
Methenamine Interactions
What other drugs affect Methenamine?
Do not take methenamine without first talking to your doctor if you are taking:
- a carbonic anhydrase inhibitor such as acetazolamide (Diamox), dichlorphenamide (Daranide), or methazolamide (Glauctabs, MZM, Neptazane)
- a sulfa product such as sulfadiazine, sulfamethoxazole (Bactrim, Septra, others), sulfasalazine (Azulfidine), and others
- a diuretic (water pill); or
- a product that contains aluminum, calcium, magnesium, sodium bicarbonate, potassium or sodium citrate, or citric acid (such as antacids, vitamin or mineral pills, urinary alkalinizers, and other medications)
You may not be able to take methenamine, or you may require a dosage adjustment or special monitoring during treatment if you are taking any of the medicines listed above.
Drugs other than those listed here may also interact with methenamine. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including vitamins, minerals, and herbal products.
What should I avoid 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.
Methenamine Dosage
How should I take Methenamine?
Take methenamine exactly as directed by your doctor. If you do not understand these instructions, ask your doctor, nurse, or pharmacist to explain them to you.
Take each dose with a full glass of water. Plenty of fluid should be consumed while taking methenamine.
Methenamine should be taken with food to reduce stomach upset.
Do not crush or chew the enteric-coated tablets. Swallow them whole. They are specially formulated to be less irritating to the stomach. Talk to your doctor if swallowing the tablets is difficult.
Shake the liquid form of methenamine well before measuring a dose. To ensure that you get the correct dose, measure the suspension with a dose-measuring spoon, dropper, or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one.
It is important to take methenamine at regularly scheduled intervals to get the most benefit.
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.
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.
Store methenamine at room temperature away from moisture and heat.
What happens if I overdose on Methenamine?
Seek emergency medical attention if an overdose is suspected.
Symptoms of a methenamine overdose are not known.
What happens if I miss a dose of Methenamine?
Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the dose you missed and take only the next regularly scheduled dose. Do not take a double dose of this medication unless otherwise directed by your doctor.
Edited from everydayhealth.com