Methenamine is used in the treatment and prevention of bacterial infections of the bladder.
This medicine may be used to treat other conditions as decided by your doctor.
Take Methenamine exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.
If you have difficulty swallowing tablets, you may crush the tablets and mix it with glass of water, milk, or fruit juice. Stir and drink immediately.
Methenamine must be taken at regular intervals as instructed. Continue to take this medicine even when you feel better. Do not stop taking it unless instructed by the doctor.
Do not skip any doses. You must complete the entire course of antibiotic. If you don't, the infection will not clear completely.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.
DO NOT double a dose under any circumstances.
If you often forget to take your medicine, let your doctor and pharmacist know.
Do not take Methenamine if you have a history of allergic reactions (swollen eyes or mouth, difficulty breathing, rashes) to this medicine.
Alert your doctor if you have the following conditions:
- severe dehydration
- severe liver disease
- kidney disease
as Methenamine may not be suitable for you.
DO NOT take Methenamine if you are currently taking a certain type of antibiotic called sulfonamides e.g. sulfadiazine, sulfamethoxazole, sulfadoxine, sulfisoxazole.
Inform your doctor if you have gout (abnormal metabolism of uric acid) or liver disease.
Let your doctor know if you are pregnant or breastfeeding.
For as long as you are taking Methenamine, you may need to have urine tests and liver function tests to check your body's response to the medicine. Your doctor will advise you about how often you need to have these tests.
Methenamine may cause any of the following side effects: stomach upset, nausea, vomiting, painful and difficult urination, rashes and itching of the skin.
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
DO NOT take Methenamine if you are currently taking a certain type of antibiotic called sulfonamides e.g. sulfadiazine, sulfamethoxazole, sulfadoxine, sulfisoxazole.
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicines for decreasing the acidity of urine e.g. potassium citrate
- medicines for neutralising stomach acid e.g. calcium carbonate, aluminium hydroxide, magnesium hydroxide
- medicines for water retention (water pills) e.g. chlorothiazide
- medicines for glaucoma (increased pressure in the eyes) e.g. acetazolamide
This list does not include all medicines that may interact with Methenamine.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.
Your doctor may advise you to drink cranberry juice while you are being treated with Methenamine. This will help improve the absorption of the medicine.
Avoid taking Methenamine together with foods that may decrease the acidity of urine such as wheat grass, cucumber, broccoli, soy beans and avocado. Ask your doctor about the types of food you should avoid.
Avoid alcohol.
Store in a cool, dry place away from the reach of children.
Medicines must not be used past the expiry date.
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