Cranberry: How It Works, Evidence & Safety

Last updated: June 2026 · Reviewed by the FactoWiki Editorial Team

Cranberry contains compounds (PACs) studied for reducing recurrent urinary-tract infections in some people. It is a common women's urinary-support ingredient.

What is Cranberry?

Cranberry is a tart red berry whose proanthocyanidins (PACs) are studied for urinary-tract support, available as juice, powder or extract.

How Cranberry works

Cranberry PACs are thought to make it harder for certain bacteria to stick to the urinary-tract lining, which is the rationale for their use in prevention.

What the evidence says

• The NIH reviews cranberry for urinary-tract infections, noting it may help prevent recurrent UTIs in some people but is not a treatment. (NIH NCCIH)

How much do studies use?

Products vary widely in PAC content; studies that show benefit generally use standardised PAC amounts. Follow label guidance.

Safety and side effects

Generally safe as a food and supplement; large amounts may cause stomach upset.

Who should avoid Cranberry?

Cranberry is not a treatment for an active UTI - that needs medical care. People on warfarin should check with a doctor.

Frequently asked questions

Does cranberry prevent UTIs?

Research suggests it may help reduce recurrent UTIs in some people, but results are mixed and it is prevention support, not a cure.

Can cranberry treat a UTI I already have?

No. An active urinary-tract infection needs medical assessment and often antibiotics - see a doctor.