Drinking lots of cranberry juice is no way to fix a urine infection, say new draft guidelines from health body the National Institute for Health and Care Excellence.
Although some studies have claimed it may help, NICE says there is not enough good evidence to recommend it.
Instead, people should drink plenty of water or fluids and take painkillers.
They can also speak to their doctor who might prescribe antibiotics, but these drugs will not always be necessary.
Urinary tract infections (UTIs) are caused by bacteria. Sometimes the body can fight a mild infection alone without medication.
When antibiotics are needed, the shortest course that is likely to be effective should be prescribed to reduce the risk of antimicrobial resistance, says NICE.
It might be more appropriate to get a back-up prescription to be used only if symptoms do not improve within 48 hours or if they worsen rapidly or significantly at any time.
Signs and symptoms of a UTI include:
- pain, burning or stinging when you urinate
- needing to urinate more often or urgently than normal
- dark, cloudy or smelly urine
- pain in the lower abdomen
- feeling generally unwell, achy, sick and tired
Professor Mark Baker, director for the centre of guidelines at NICE, said: "We recognise that the majority of UTIs will require antibiotic treatment, but we need to be smarter with our use of these medicines.
"Our new guidance will help healthcare professionals to optimise their use of antibiotics.
"This will help to protect these vital medicines and ensure that no one experiences side effects from a treatment they do not need."
A consultation on the draft guidelines for England will close on 5 June.