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Urex Side Effects Center
Medical Editor: John P. Cunha, DO, FACOEP
Urex (methenamine hippurate) is a urinary tract antiseptic drug used to treat and prevent urinary tract infections. Urex is available in generic form. Common side effects of Urex include nausea, upset stomach, vomiting, diarrhea, abdominal cramps, loss of appetite, and skin rash.
The dose of Urex for adults and children over 12 years of age is 1 tablet (1 g) twice daily, and one-half tablet or one tablet (0.5 or 1 g) twice daily for children 6 to 12 years of age. Urex may interact with carbonic anhydrase inhibitors, sulfa drugs, diuretics (water pills), or products containing aluminum, calcium, magnesium, sodium bicarbonate, potassium or sodium citrate, or citric acid (such as antacids, vitamin or mineral pills, urinary alkalinizers, and other medications). Tell your doctor all medications and supplements you use. During pregnancy, Urex should be used only when prescribed. This drug passes into breast milk and the effect on a nursing infant is unknown. Consult your doctor before breast-feeding.
Our Urex (methenamine hippurate) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What is Patient Information in Detail?
Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.
Urex in Detail - Patient Information: Side Effects
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.
Read the entire detailed patient monograph for Urex (Methenamine Hippurate)
What is Patient Information Overview?
A concise overview of the drug for the patient or caregiver from First DataBank.
Urex Overview - Patient Information: Side Effects
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.
Read the entire patient information overview for Urex (Methenamine Hippurate)
What is Prescribing information?
The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.
Urex FDA Prescribing Information: Side Effects
Adverse effects of UREX (methenamine hippurate) have been reported in fewer than 3.5% of patients treated.
Children have received UREX (methenamine hippurate) at the recommended dosages as a prophylactic/suppressive regimen after initial treatment of acute episodes of pyuria. Side effects were encountered in only 1.1% of these children.
Read the entire FDA prescribing information for Urex (Methenamine Hippurate)
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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.
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