Cranberry Extract
The go-to supplement for preventing urinary tract infections. Cranberry extract contains PACs (proanthocyanidins) that stop bacteria from sticking to your bladder wall.
Cranberry extract works by delivering A-type proanthocyanidins (PACs) that prevent E. coli bacteria from adhering to the cells lining your urinary tract. If bacteria can't stick, they get flushed out before they can cause an infection.
Good for you if: You get recurrent UTIs (2+ per year), want a non-antibiotic prevention strategy, or want to maintain urinary tract health — especially relevant for women.
Dive deeper into the researchCommon side effects
- Mild GI discomfort in some people
- May interact with blood thinners (warfarin)
- High doses of juice (not extract) can cause kidney stones in susceptible people
What does cranberry extract do?
Most UTIs happen when E. coli bacteria travel from your gut to your urethra and attach to the bladder wall using tiny hair-like structures called fimbriae. Once attached, they multiply and cause infection.
Cranberry's A-type PACs block these fimbriae from grabbing onto your bladder cells. The bacteria can't attach, so they get washed away when you urinate. It's prevention, not treatment.
What can you expect?
- Fewer UTIs — studies show ~35% reduction in recurrent UTIs
- Less antibiotic use — reduces the need for repeated antibiotic courses
- Ongoing protection — works best as a daily preventive, not as treatment
How to take it
Take a cranberry extract standardised to 36 mg PACs daily — once or twice daily with water. Look for "A-type proanthocyanidins" on the label.
Capsules/tablets are more effective than juice. Juice often contains too much sugar and too few PACs to be reliably preventive.
Not a treatment: Cranberry extract prevents UTIs — it does not treat an active infection. If you have UTI symptoms (burning, frequency, urgency), see a doctor for antibiotics.
Combine with: D-mannose (500 mg–2 g/day) for a dual-mechanism approach. D-mannose works through a different anti-adhesion pathway and together they provide stronger protection.
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Get early accessFrequently Asked Questions
Does cranberry juice work as well as extract?
No. Most commercial cranberry juices contain too much sugar and too few A-type PACs to be reliably preventive. You'd need to drink large amounts of unsweetened juice daily. Standardised extract capsules (36 mg PACs) are more effective, more convenient, and don't add sugar.
Cranberry vs D-mannose — which is better for UTIs?
They work through different mechanisms and are both effective. Cranberry PACs prevent bacterial adhesion via fimbriae blocking. D-mannose acts as a decoy that bacteria bind to instead of your bladder wall. For maximum prevention, many people combine both.
Can cranberry extract treat an active UTI?
No. Cranberry is for prevention only. Once bacteria have established an infection, you need antibiotics. Don't delay treatment hoping cranberry will clear an active UTI — untreated UTIs can progress to kidney infections.
Is cranberry extract safe during pregnancy?
Generally yes — cranberry extract at standard doses is considered safe during pregnancy, when UTIs are more common. However, check with your OB-GYN before starting any supplement during pregnancy.
How it works in your body
A-type proanthocyanidins (PACs) in cranberry have a unique molecular structure that blocks the P-fimbriae on E. coli bacteria. These fimbriae are the "hooks" that E. coli uses to attach to uroepithelial cells. With PACs present, the bacteria can't latch on and are flushed out during urination.
B-type PACs (found in many other fruits) don't have this anti-adhesion effect. This is why cranberry specifically — with its high A-type PAC content — works for UTI prevention while other berries don't.
What the studies show
- UTI reduction: Cochrane meta-analysis (2023) found cranberry products reduce risk of recurrent UTIs by ~35%
- Women: Most effective in women with recurrent UTIs (2+ per year)
- Dose matters: Products providing ≥36 mg PACs/day were consistently effective; lower doses were not
- Vs antibiotics: Not as effective as daily low-dose antibiotics for prevention, but avoids antibiotic resistance
Side effects & safety
Cranberry extract is very well-tolerated:
- GI discomfort — Mild nausea or stomach upset in some people, usually resolves with food.
- Warfarin interaction — Cranberry may slightly increase the anticoagulant effect of warfarin. Monitor INR if on blood thinners.
- Kidney stones — High-dose cranberry juice (not extract) can increase oxalate excretion. Not a concern at standard extract doses.
Safe for most people: No significant safety concerns at standard supplemental doses (36 mg PACs/day).
Which labs to check
No routine labs needed for cranberry extract. For recurrent UTI management:
- Urinalysis & culture — to confirm UTI when symptoms occur
- Fasting glucose / HbA1c — diabetes increases UTI risk
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