Vitamin C and Hiprex in rUTI

Inclusion Criteria: * Female * Age ≥18 years * Recurrent proven UTI, defined as "two or more proven infections in six months or three or more infections in six months" * Willing and able to give fully informed consent * Patients suitable for prophylaxis following discussion with their clinician. * No contra-indications to treatment with methenamine hippurate or Vitamin C * All women will have undergone standard diagnostic work-up and have followed routine conservative UTI prevention measures. * A working email address to be used to submit urine pH results * Willing and able to comply with the study procedures * Females of childbearing potential must be willing to use a highly effective method of contraception (hormonal or barrier method of birth control; abstinence; sterilisation or vasectomised partner) Exclusion Criteria: * Males * Women who are pregnant or breast-feeding * Contraindications to methenamine hippurate as described in BNF: known allergy, gout, severe metabolic acidosis, severe dehydration, eGFR less than 10 ml/min, severe hepatic impairment * Currently using vitamin C containing supplement or cranberry extract tablets * Women using urinary alkalinisation agents, e.g potassium citrate, sodium bicarbonate * Currently receiving any form of bladder instillation or intradetrusor Onabotulinum Toxin A injections * Patients already on low-dose antibiotics or methenamine hippurate (due to delay that will be incurred by 3-month washout period) * Indwelling urinary catheter in situ or performing clean intermittent self-catheterisation * Correctable urinary tract abnormalities, e.g., urinary tract calculi, urinary retention * Formation of ileal conduit or augmented bladder * Neurogenic bladder dysfunction * Hyperoxaluria