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Quick answer
Cranberry products, including juice, tablets and capsules, may lower the chance of getting another urinary tract infection (UTI) in some people, especially women who keep getting them. A large Cochrane review in 2023 found that cranberry probably reduces the number of UTIs with symptoms in women with recurrent UTIs, in children, and in people at risk after certain medical procedures.
Cranberry is about prevention only. Health authorities agree there is no evidence that it relieves symptoms or clears an infection you already have. If you think you have a UTI, speak to a pharmacist or doctor rather than drinking more cranberry juice. People taking warfarin should avoid cranberry products, according to the NHS.
What the research says
The Cochrane review (2023). Williams and colleagues pooled 50 randomised controlled trials with 8,857 participants, making this the most complete summary of the evidence so far. Across the trials that compared cranberry with placebo, water or no treatment, cranberry was linked with about 30% fewer UTIs, and the reviewers rated this as moderate-certainty evidence. The results differed by group:
- Women with recurrent UTIs: about 26% fewer UTIs with symptoms that were confirmed by a urine test (8 studies, 1,555 women).
- Children: about 54% fewer UTIs (5 studies, 504 children).
- People at risk after a medical intervention, such as a bladder-related procedure: about 53% fewer UTIs (6 studies, 1,434 people).
- Little or no benefit was found in older people living in care homes, in pregnant women, or in adults with bladder-emptying problems caused by nerve conditions.
The reviewers found no clear difference between low, medium and high doses of the active compounds, and the evidence comparing juice with tablets was of very low certainty. The results also varied considerably between studies.
NCCIH (US National Institutes of Health). The National Center for Complementary and Integrative Health summarises that cranberry products may reduce repeat UTIs with symptoms in women by about 25%, but results are inconsistent, so how well they work remains uncertain. It explains that the leading theory is that plant compounds called proanthocyanidins (PACs) stop bacteria from sticking to the bladder wall. Processing cranberries into tablets or capsules can lower PAC levels.
NICE (UK guideline). The National Institute for Health and Care Excellence says that some women who are not pregnant may wish to try cranberry products as self-care for recurrent UTIs. NICE rated the evidence as very low quality and found no evidence of benefit in older women. In the studies it reviewed, capsules showed a benefit but juice was not clearly better than placebo, although the evidence was too limited to recommend a particular product.
Put together, the evidence is rated moderate: there is a large body of trials with a modest benefit for certain groups, but the results are inconsistent and expert bodies disagree on how much weight to give them.
How to use it
There is no agreed dose. The Cochrane review found no clear difference between lower and higher doses, and NICE did not recommend a specific product. Practical points from the sources:
- Choose a form that suits you. Juice, tablets and capsules have all been studied. Juice can be high in sugar, while tablets and capsules may contain less of the active compounds after processing.
- Watch the sugar. NICE and the NHS both point out that cranberry products can be high in sugar. The NHS advises limiting fruit juice to 150 ml a day in total.
- Think prevention, not treatment. Cranberry is used regularly to try to prevent repeat infections. It should not be used to treat an infection.
Cranberry works best alongside simple habits. NICE and the NHS suggest:
- Drinking enough fluids to avoid dehydration
- Not holding in your pee, and peeing soon after sex
- Wiping from front to back after using the toilet
- Avoiding douching, scented soaps around the genitals, and tight or non-breathable underwear
- Wearing cotton underwear
Possible side effects and interactions
Cranberry taken by mouth is generally considered safe, according to NCCIH. The Cochrane review found that few people reported side effects, with stomach pain the most common, and there was probably no clear difference in digestive side effects compared with placebo. NCCIH notes that very large amounts can cause stomach upset and diarrhoea, especially in young children.
Other points:
- Warfarin: The NHS advises people who take warfarin, a blood-thinning medicine, to avoid cranberry products. NCCIH says the evidence on this interaction is conflicting and advises talking to a health professional first.
- Sugar and teeth: Sweetened cranberry juice adds free sugars. The NHS notes that sugar from juice can damage teeth, and that drinking juice with meals reduces this risk.
- During an infection: The NHS self-care advice for a UTI suggests limiting drinks that can irritate the bladder, including fruit juice, coffee and alcohol.
Who should be careful
- People taking warfarin or other medicines: check with a doctor or pharmacist first.
- Pregnant or breastfeeding women: NCCIH says amounts found in food appear safe but the evidence for larger amounts is not conclusive, and the NHS advises checking with a doctor first. The Cochrane review found little or no benefit in pregnancy.
- Children and teenagers under 16: although the Cochrane review found a possible benefit in children, NICE advises using cranberry products only after advice from a children's specialist, so that proper treatment is not delayed.
- People with diabetes or watching their sugar intake: choose unsweetened products and check labels.
- Older people in care homes and people with bladder-emptying problems: the evidence suggests little or no benefit, so medical advice is more useful.
When to see a doctor
The NHS says a pharmacist can help women aged 16 to 64 who are not pregnant and have a suspected UTI. Get an urgent GP appointment or call NHS 111 (or your local equivalent) if you have UTI symptoms and:
- You are a man, are pregnant, are aged 65 or over, or the UTI is in a child
- You have a very high or very low temperature, or feel hot, cold or shivery
- You have pain in your lower tummy or in your back just under the ribs
- You see blood in your pee
- Your symptoms get worse quickly or do not improve within 48 hours of starting treatment
- You have diabetes, a weakened immune system or a urinary catheter
- You have had 2 UTIs in 6 months or 3 in 12 months
Call 999 or go to A&E (or your local emergency number) if you or your child become confused, very drowsy or have difficulty speaking. A kidney infection can be serious and can lead to sepsis. If you get recurrent UTIs, a doctor can discuss other options to prevent them.
Frequently asked questions
Does cranberry juice cure a UTI?
No. The NHS says there is no evidence that cranberry relieves symptoms or treats an active infection. NCCIH also says it is not recommended as a treatment for an existing UTI.
Are cranberry tablets better than juice?
It is not clear. NICE found that capsules showed a benefit in its evidence review while juice did not clearly beat placebo, but the Cochrane review rated the evidence comparing juice and tablets as very low certainty. Tablets do avoid the sugar in juice.
How much cranberry should I take?
There is no agreed dose. The Cochrane review found no clear difference between low, medium and high doses of the active compounds. Follow the label of your chosen product, and if it is juice, keep to the NHS limit of 150 ml of fruit juice a day.
Can men use cranberry to prevent UTIs?
The groups that benefited in the Cochrane review were women with recurrent UTIs, children and people at risk after medical procedures; the sources reviewed for this article do not single out men as a group that benefits. A UTI in a man needs medical assessment, according to the NHS, so men should see a doctor rather than relying on cranberry.