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Cranberry Kidney Stones: What a Safety Review Says and What It Leaves Open
Cranberry kidney stones is a question with a mixed answer. A US Pharmacopeial safety review named stone formation as a possible risk and then called the data contradictory, with some reports pointing to lower risk. FemiPro's cranberry line weighs at most 175 mg, and the label gives no stone warning of its own.
Written by the FemiPro label deskUpdated · 4 min read
The question01
Does cranberry cause kidney stones?
No one can say that cranberry causes kidney stones, because the evidence points both ways. A US Pharmacopeial Convention safety review listed kidney stone formation as a potential risk, then described the data as contradictory (Madden 2021, cranberry safety (stones, warfarin)).
The same review noted that some reports suggest cranberry may lower the risk. That split matters, because a safety review that finds both signals cannot give a clean yes or no. Where the record is mixed, the careful move is to treat your own history as the deciding fact.
So the honest summary is that a link is possible, unproven and not settled in either direction.
The review's overall finding was calm: cranberry ingredients are not known to carry serious risks when consumed properly in supplements. The two items it flagged to watch were stones and warfarin. NCCIH, which calls cranberry generally safe by mouth, does not discuss stones at all (NCCIH, Cranberry).
Inside one capsule02
How much cranberry is in a FemiPro capsule?
A FemiPro capsule holds at most 175 mg of cranberry extract, and it may hold far less. The label does not print the weight of the line.
The ceiling comes from the label order. The herbal blend is 350 mg, and cranberry is the second of four lines listed by weight, so it can weigh no more than 350 divided by 2 (21 CFR 101.36, supplement labeling). At 30% PACs that is about 52 mg of proanthocyanidins at most.
Set that beside the amount the USP review tied to warfarin signals, 3,000 mg a day of extract. A single capsule's ceiling is about one seventeenth of that figure (175 into 3,000 is about 17). That comparison is about warfarin, not stones, so use it only to see how small the line is. It is not a safe-dose claim.
| Item | Amount |
|---|---|
| Most cranberry extract in one FemiPro capsule | 175 mg (a ceiling, not printed) |
| Most PACs in that extract at 30% | about 52 mg |
| Extract intake tied to warfarin signals in the USP review | 3,000 mg a day |
| Label dose of FemiPro | 1 capsule a day |
Before you start03
Who should ask a clinician before taking cranberry?
Anyone with a history of kidney stones should ask a clinician before taking cranberry capsules, because the stone question is open. So should anyone on warfarin or with a known medical condition. The FemiPro label asks people with a known medical condition to consult a physician first.
Use the quick check below to see which cautions apply to you. It sorts the usual FemiPro cautions and does not replace advice.
Keep taking prescribed medicine, and do not stop a stone prevention plan because of a supplement. See the FemiPro side effects page for the wider list.
FemiPro: from $49 a bottle30 capsules · 1, 3 or 6 bottles · free US shipping · 60-day money-back guarantee
See packsWarning signs04
What signs of a kidney stone need medical care?
Seek care for severe pain in your side or back, blood in your urine, fever with chills, or trouble passing urine. These can signal a stone, an infection or a blockage. None is a reason to wait for a supplement to work.
NIDDK and CDC both list blood in the urine and inability to pass urine as reasons to seek prompt care, and CDC lists back or side pain with fever as a sign of a kidney infection (NIDDK, Incontinence causes and when to get care) (CDC, UTI basics). A capsule cannot sort out which problem you have.
One practical habit helps whatever the cause: drink the 6 to 8 oz of water the label directs with the capsule, and keep your overall fluids steady, as your clinician advises. If you want a record, note any pain, color change or urgency in a diary and bring it to the visit.
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FAQ05
Cranberry and stone questions, answered
Can I take FemiPro if I have had a kidney stone?
Ask your clinician first. The label asks anyone with a known medical condition to consult a physician, and the cranberry stone evidence is contradictory. Bring the Supplement Facts panel to the visit.
Does cranberry juice raise stone risk more than capsules?
The sources used here do not compare forms for stones. The USP review calls the stone data contradictory for cranberry ingredients in general, so no form can be called safer.
Will cranberry dissolve a kidney stone?
No source here says so. Cranberry research covers repeat urinary infections, not stones. A stone that causes pain or blocked urine needs a clinician, not a supplement.
Who wrote this06
Written and reviewed by
Pages built from the label, the sales page and linked NIH, FDA, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by a U.S. stocking partner for FemiPro, not by the manufacturer or the label's distributor. We earn money when you buy through our order links.
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More about FemiPro
U.S. stocking partner for FemiPro
Ready to try FemiPro?
Check your medicines first, then pick a pack. Every pack ships free in the US, six bottles cost the least per bottle, and each order carries the 60-day money-back guarantee.
- Secure checkout
- 60-day money-back guarantee
- Ships from the U.S.