methenamine - oral, Hiprex, Mandelamine, Urex (cont.)
HOW TO USE: Take this medication by mouth as directed by your doctor. Dosage is based on the brand of methenamine you are prescribed, your medical condition, and your response to treatment. For children, dosage is also based on age and weight.Methenamine works better if your urine is more acidic. Your doctor may test the acidity of your urine (urine pH). If necessary, your doctor may recommend ways to increase urine acidity (such as by taking vitamin C/drinking cranberry juice, limiting foods that decrease acidity/increase alkalinity such as milk products/most fruits, adjusting alkalinizing medications). See also Drug Interactions section. Follow your doctor's instructions.Antibiotics work best when the amount of medicine in your body is kept at a constant level. Therefore, take this drug at evenly spaced intervals. To help you remember, take it at the same times each day.Continue to take this medication for the full time prescribed, even if you feel well. Skipping doses or stopping the medication too early may allow bacteria to continue to grow, which may result in a return of the infection and make the bacteria more difficult to treat (resistant). Do not take more of this drug than directed because it may increase your chance of side effects.Tell your doctor if symptoms of a urinary tract infection return (such as burning/painful/frequent urination).
SIDE EFFECTS: Nausea, vomiting, diarrhea, abdominal cramps, and loss of appetite may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.Painful or difficult urination may occur with methenamine, although less often. Report these side effects to your doctor, who may need to lower your dose of methenamine or change your treatment to make your urine less acidic.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Taking higher than recommended doses of methenamine may cause bladder irritation, painful/frequent urination, and bloody/pink urine. Tell your doctor immediately if you have any of these symptoms.Tell your doctor immediately if any of these unlikely but serious side effects occur: mouth sores, unusual headache, ringing in the ears, muscle cramps, swelling of the arms/legs.A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Medically Reviewed by a Doctor on 4/16/2014
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Need help identifying pills and medications?
Back to Medications Index
- Allergic Skin Disorders
- Bacterial Skin Diseases
- Bites and Infestations
- Diseases of Pigment
- Fungal Skin Diseases
- Medical Anatomy and Illustrations
- Noncancerous, Precancerous & Cancerous Tumors
- Oral Health Conditions
- Papules, Scales, Plaques and Eruptions
- Scalp, Hair and Nails
- Sexually Transmitted Diseases (STDs)
- Vascular, Lymphatic and Systemic Conditions
- Viral Skin Diseases
- Additional Skin Conditions