What is Methenamine Hippurate used for?

It is used to prevent or manage recurring urinary tract infections when long-term treatment is necessary.

Can I take Methenamine Hippurate if I have liver problems?

No, it is not recommended for people with severe liver issues because it can cause harmful side effects like liver failure.

How much Methenamine Hippurate should I take?

Adults and children over 12 usually take 1g twice daily, while children 6-12 take 0.5g to 1g twice daily.

Will Methenamine Hippurate work if my urine is not acidic?

The drug works better in acid urine, so you may need to avoid certain foods or medicines that make urine less acidic.

Is Methenamine Hippurate safe to take while breastfeeding?

The drug can pass into breast milk, so you should discuss with a doctor whether to stop nursing or stop the medication.

What are the most common side effects of Methenamine Hippurate?

The most common side effects are nausea and vomiting.

Can Methenamine Hippurate be used during pregnancy?

It should only be used if the benefits outweigh the potential risks to the fetus.

What should I do if I take too much Methenamine Hippurate?

Seek medical help immediately; doctors may use vomiting induction, gastric lavage, or activated charcoal.

methenamine hippurate | CAS 5714-73-8 | ROAIXOJGRFKICW

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Urinary tract antiseptic (antibacterial)

Methenamine Hippurate is an antibacterial medicine used to help prevent or manage frequent urinary tract infections. It works by turning into formaldehyde in acidic urine, which helps kill bacteria. It is typically used for long-term prevention after an initial infection has been treated with other medicines.

How it worksThe drug turns into formaldehyde when it hits acidic urine, which stops bacteria from growing by attacking their DNA.

Brand names:HIPREX, UREX

Used for

Preventing or managing frequent urinary tract infections (UTIs) when long-term treatment is needed.

Conditions

Urinary tract infections

Class

AntibacterialAntisepticUrinary tract antiseptic (antibacterial)UrinaryHepatic

How to take

FormsTablet

RoutesOral

Adults and children over 12 usually take 1 gram twice a day. Children aged 6 to 12 take 0.5 to 1 gram twice a day.

This medicine works best when urine is acidic. You may need to avoid foods or medicines that make your urine less acidic.

Key warnings

·People with liver problems may have bad reactions because the drug produces small amounts of ammonia and formaldehyde.
·Do not use this as the only treatment for a serious infection that is causing symptoms throughout the whole body.

Do not use if

·People with kidney failure
·People with severe liver problems
·People who are severely dehydrated

Side effects

Common

NauseaVomitingRashItchingPain during urination

Serious

·Liver problems (especially in people with existing liver issues)
·Acute liver failure

Seek help if

·Signs of liver failure
·Severe dehydration

Interactions

·Taking this with sulfamethizole or sulfathiazole can cause crystals (precipitate) to form in your urine.
·Known interactions include Furadantin, Ivadantin, Capitrol, Actin-N, Furoxone, Tindamax, and Solosec.

FoodFoods that make your urine less acidic can make this medicine less effective.

Special populations

PregnancyMethenamine Hippurate can pass to a fetus. It should only be used during pregnancy if the benefit to the mother is greater than the risk to the baby.

BreastfeedingMethenamine can be passed into breast milk. Mothers should decide whether to stop breastfeeding or stop the medicine based on the importance of the drug to the mother.

PediatricFor children aged 6 to 12, the dose is half a tablet or one full tablet twice daily. It is used after an initial infection has been cleared.

GeriatricThe drug is excreted through the kidneys; older patients or those with kidney issues should be monitored as the hippurate part is cleared through the kidneys.

Talk to your doctor

Monitor

·Urinary pH
·Urinary cultures to check efficacy
·Liver function

Questions to ask

·Is my liver function healthy enough for this drug?
·Should I change my diet to keep my urine acidic?
·Are my other medications safe to take with Methenamine Hippurate?

Pharmacokinetics

OnsetAntibacterial activity is seen in urine within 30 minutes of a 1g dose.

DurationContinuous antibacterial activity is seen with twice-daily dosing.

BioavailabilityReadily absorbed from the GI tract.

MetabolismThe methenamine component is hydrolyzed to formaldehyde in acid urine.

ExcretionOver 90% of the methenamine is excreted in urine within 24 hours.

Practical

OverdoseIf someone takes too much, doctors may try to make them vomit or use activated charcoal. It is also important to drink plenty of fluids.

Ingredients

Inactive

magnesium stearatepovidonesaccharin sodium

Educational summary derived from FDA labeling, AI-assisted. Not medical advice — consult a healthcare professional. Updated 2026-04-25.