According to research reviewed by Gram, a 2026 analysis of FDA safety reports from 2004-2021 found that ginger, butcher’s broom, and valerian supplements showed statistically significant warning signals for kidney problems. Ginger appeared in kidney-problem reports 6.21 times more often than expected, butcher’s broom 7.99 times more often, and valerian 2.03 times more often. While these signals don’t prove the supplements caused kidney damage, they highlight the need for medical monitoring in people who use them regularly.
A Gram Research analysis of over 17 years of FDA safety reports found that certain popular herbal supplements—including ginger, butcher’s broom, and valerian—may be linked to kidney problems more often than expected. While these products are sold as natural and safe, researchers discovered warning signals suggesting they could damage kidneys in some people. The study doesn’t prove these supplements definitely cause kidney harm, but it highlights the need for doctors to monitor patients who take them and for more research to understand the risks.
Key Statistics
A 2026 analysis of FDA adverse event reports from 2004-2021 found that ginger supplements appeared in kidney-problem reports 6.21 times more often than statistically expected, based on 11 documented cases.
According to a Gram Research review of FDA data, butcher’s broom showed a reporting odds ratio of 7.99 for kidney-related adverse events, making it nearly 8 times more likely to be reported with kidney problems than would occur by chance.
A retrospective pharmacovigilance study identified 63 natural products with disproportionate kidney-problem reporting signals, with ginger, butcher’s broom, and valerian showing the strongest statistical associations.
Valerian supplements demonstrated a reporting odds ratio of 2.03 for kidney adverse events in FDA data analysis, suggesting kidney problems were reported approximately twice as often as expected by chance.
The Quick Take
- What they studied: Whether herbal and dietary supplements cause kidney damage by analyzing reports of kidney problems linked to natural products
- Who participated: Analysis of 15 documented cases of kidney problems reported to the FDA between 2004 and 2021 involving three specific supplements: ginger, butcher’s broom, and valerian
- Key finding: Three herbal supplements showed statistically significant warning signals for kidney problems: ginger appeared 11 times more often than expected (6.21 times higher), butcher’s broom 8 times higher, and valerian 2 times higher
- What it means for you: If you take ginger, butcher’s broom, or valerian supplements regularly, talk to your doctor about monitoring your kidney health. This doesn’t mean you’ll definitely have problems, but awareness and medical supervision are important
The Research Details
Researchers looked at the FDA’s database of adverse event reports—a collection of safety complaints submitted by patients and healthcare providers from 2004 to 2021. They searched for reports mentioning kidney problems linked to herbal or dietary supplements. Using statistical methods, they calculated whether certain supplements appeared in kidney-problem reports more often than would be expected by chance alone. When a supplement showed up significantly more often than expected, it was flagged as a potential warning signal. The team then reviewed medical literature to see if there was any scientific evidence supporting these signals.
This approach is important because it can detect safety problems that might not show up in traditional clinical trials. Herbal supplements are used by millions of people but are less strictly regulated than prescription drugs, so safety problems may go unnoticed. By analyzing real-world reports, researchers can identify potential risks that need further investigation.
This study has important limitations: it found only 15 total cases, which is a small number for drawing firm conclusions. The analysis can show that supplements appear in kidney-problem reports more often than expected, but it cannot prove the supplements actually caused the kidney damage—other factors could be involved. The findings suggest the need for more rigorous research, not definitive proof of harm.
What the Results Show
The analysis identified 231 different combinations of kidney problems and natural products in the FDA database. However, only three supplements showed statistically significant warning signals. Ginger had the strongest signal, appearing in 11 cases of kidney problems with a reporting odds ratio of 6.21, meaning kidney problems were reported about 6 times more often with ginger than would be expected by chance. Butcher’s broom appeared in 2 cases with a reporting odds ratio of 7.99 (nearly 8 times more often than expected), and valerian appeared in 2 cases with a reporting odds ratio of 2.03 (about 2 times more often than expected). These three supplements stood out from the other 60 natural products examined because their signals met the study’s threshold for statistical significance.
The study identified 63 natural products total that had some disproportionate reporting of kidney problems, though most did not reach the level of statistical significance. This suggests that while ginger, butcher’s broom, and valerian warrant closer attention, other supplements may also pose potential risks that need monitoring. The researchers noted that kidney damage can occur through different mechanisms: the active ingredients in supplements might directly harm kidneys, contaminants in the products might be toxic, or supplements might interact dangerously with medications people are taking.
Previous research has documented kidney damage from certain prescription medications, but studies on herbal supplement safety have been limited. This analysis adds to growing evidence that natural products are not automatically safe just because they come from plants. The findings align with earlier case reports suggesting ginger and valerian can cause kidney problems in some individuals, though large-scale studies confirming this remain lacking.
The study’s main limitation is its small sample size—only 15 cases met the criteria for significant signals. This makes it impossible to prove these supplements definitely cause kidney damage. The analysis also cannot account for other factors that might have caused kidney problems, such as pre-existing kidney disease, other medications, or dehydration. Additionally, the FDA database relies on voluntary reporting, so many cases may go unreported. The findings represent warning signals that need further investigation, not confirmed causes of kidney harm.
The Bottom Line
If you regularly take ginger, butcher’s broom, or valerian supplements, inform your doctor and ask about monitoring your kidney function through blood tests. This is especially important if you have existing kidney disease, take medications that affect kidneys, or are over age 65. For the general population without kidney concerns, occasional use of these supplements is likely low-risk, but long-term daily use warrants medical supervision. Confidence level: Moderate—the warning signals are real but not yet proven to cause harm.
People with existing kidney disease, those taking multiple medications, older adults, and anyone planning long-term supplement use should pay special attention. Healthcare providers should be aware of these potential signals when patients report kidney problems. People considering starting these supplements should discuss it with their doctor first, particularly if they have risk factors for kidney disease.
Kidney damage from supplements typically develops gradually over weeks to months of regular use, though acute reactions are possible. If you experience symptoms like changes in urination, swelling in legs or face, fatigue, or back pain while taking these supplements, contact your doctor immediately. Kidney function improvements after stopping a problematic supplement may take weeks to months.
Frequently Asked Questions
Can herbal supplements like ginger damage your kidneys?
Ginger, butcher’s broom, and valerian showed warning signals for kidney problems in FDA data, appearing more often in kidney-problem reports than expected. However, this doesn’t prove they caused the damage—more research is needed. Talk to your doctor if you take these regularly.
Is it safe to take ginger supplements every day?
Occasional ginger use is generally considered safe, but daily long-term use warrants medical supervision, especially given the warning signals for kidney problems. Ask your doctor to monitor your kidney function if you take ginger regularly, particularly if you have kidney disease risk factors.
What symptoms suggest a supplement is harming my kidneys?
Watch for changes in urination (frequency, color, or amount), swelling in legs or face, persistent fatigue, back pain, or nausea. These may indicate kidney problems. Stop the supplement and contact your doctor immediately if you experience these symptoms while taking herbal products.
Do all herbal supplements cause kidney problems?
No. The study identified warning signals for only three supplements out of 63 examined. Most herbal supplements appear safe, but the research shows that ’natural’ doesn’t automatically mean risk-free. Individual responses vary based on health status, medications, and dosage.
Should I stop taking ginger, valerian, or butcher’s broom?
Don’t stop without consulting your doctor. If you take these supplements regularly, discuss the warning signals with your healthcare provider. They can assess your individual risk, monitor your kidney function, and help you decide whether to continue, adjust dosage, or switch to alternatives.
Want to Apply This Research?
- Log daily supplement intake (ginger, butcher’s broom, valerian) with dosage and duration. Track any symptoms like changes in urination frequency, color, or volume; swelling; fatigue; or back pain. Record dates of kidney function tests (creatinine and BUN levels) to monitor trends over time.
- Set a monthly reminder to review your supplement use with your doctor. If taking one of the three flagged supplements, establish a baseline kidney function test and schedule follow-up testing every 6-12 months. Document any new medications or supplements you add, as interactions may increase kidney risk.
- Create a supplement safety dashboard showing: (1) which supplements you take and how long, (2) your kidney function test results over time, (3) any symptoms you experience, and (4) conversations with your healthcare provider about these supplements. Use this to identify patterns and share with your doctor at appointments.
This article summarizes research findings and should not replace professional medical advice. The study identifies warning signals for potential kidney problems with certain supplements, but does not prove these supplements caused kidney damage in reported cases. If you take ginger, butcher’s broom, valerian, or other supplements regularly, consult your healthcare provider before making changes, especially if you have kidney disease, take medications affecting kidney function, or are over age 65. Seek immediate medical attention if you experience symptoms of kidney problems such as changes in urination, swelling, fatigue, or back pain. Always inform your doctor about all supplements you take.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.