Also called methenamine hippurate

Key points about Hiprex

  • Hiprex is used to prevent ongoing or recurrent urinary tract infections (UTIs).
  • Hiprex is also called methenamine hippurate.
  • Find out how to take it safely and possible side effects.
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Hiprex is used to prevent ongoing or recurrent urinary tract infections (UTIs). It works by causing your pee (urine) to be acidic and in this way discourages the growth of bugs. It is not effective for the treatment of UTIs but may be considered for preventing UTIs in women. Read more about UTIs in women. 

From December 2023 you can only buy Hiprex from a pharmacy after a consultation with a pharmacist or get it on a prescription from your healthcare provider.

  • In Aotearoa New Zealand, Hiprex is available as tablets (1 gram).
  • The dose of Hiprex is 1 tablet twice a day – every 12 hours is best.
  • If you have a catheter your doctor may increase your dose to 1 tablet 3 times a day.

  • Timing: It is best to take Hiprex with food such as with breakfast and dinner. Take each dose with a full glass of water. Take Hiprex regularly to prevent UTIs. Do not wait for symptoms.
  • Swallowing problems: If you find it difficult to swallow the Hiprex tablets, you can crush them and take them with a drink of milk or fruit juice. 
  • Vitamin C: Your doctor may suggest to take vitamin C which can make your urine acidic. Hiprex works best when your urine is acidic.
  • Missed dose: If you forget to take your dose, do not take a double dose to make up for a missed dose. Simply take your next dose as planned.

  • Do not take Hiprex while you are taking sulfonamide antibiotics such as co-trimoxazole. This increases your risk of kidney stones. 
  • Do not use antacids or urinary alkalinizers (such as sodium bicarbonate  or potassium citrate) while you are taking Hiprex. These cause your pee to be alkaline (opposite to acidic) which makes Hiprex ineffective. 

  • Do you have gout?
  • Do you have problems with your kidney or liver?
  • Are you pregnant?

If so, it’s important that you tell your doctor or pharmacist before you start Hiprex. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Side effects include skin rash, itching, stomach irritation, nausea (feeling sick) and vomiting (being sick). Some people may experience bladder irritation such as a burning sensation and pain on peeing.

Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product(external link)

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Maya Patel, Pharmacist, Auckland

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