In 2004 Devil's Claw Earned a Strong Evidence Grade. By 2019 a Military Panel Said Skip It.

The Oasis Health Journal · Submitted July 19, 2026 · 2:25 PM ET

Devil's claw is named for its seed pod, which is a wooden grappling hook with the temperament of a bear trap. It evolved to snag the feet of passing animals and get dragged somewhere new. Nobody looked at that thing and thought 'my knees.' They looked at it and thought 'get it off me.'

And yet the tubers underneath it have spent decades in clinical trials for joint and back pain, collecting a set of evidence grades that refuse to agree with each other. Same plant. Largely the same trials. Four different verdicts, depending on who was holding the clipboard.

2004: the strong evidence

A 2004 systematic review in BMC Complementary and Alternative Medicine went through twelve trials of Harpagophytum procumbens and handed out grades. A water extract standardized to 50 mg of harpagoside per day got strong evidence for acute flare-ups of chronic nonspecific low back pain. Powdered root at 60 mg harpagoside got moderate evidence for osteoarthritis of the spine, hip and knee. A water extract at 60 mg got moderate evidence for being no worse than 12.5 mg of rofecoxib, which you may remember under its retail name, Vioxx.

Strong evidence is the top of that scale. If the story stopped there this would be a short post and a very easy sell.

The solvent nobody prints on the front label

Here is the detail quietly doing most of the work. The same reviewers noted that 60 percent ethanol pulls out roughly half the harpagoside that water does, and they were blunt about the consequence: results from the water extracts cannot be transferred to an ethanol extract, or even to a water extract carrying less harpagoside per day.

So the grade was never awarded to devil's claw. It was awarded to one preparation at one dose. In that same paper, ethanolic extracts delivering under 30 mg of harpagoside daily landed at the bottom of the scale: limited evidence. Two bottles can both say devil's claw on the front and sit on opposite ends of the evidence table. The number worth hunting for on a label is milligrams of harpagoside per day, not milligrams of root.

2014: Cochrane reads the same trials and shrugs

Ten years later, a Cochrane review of herbal medicine for low back pain graded the literature with GRADE instead. Devil's claw standardized to 50 or 100 mg harpagoside daily, in its words, may be better than placebo for short-term improvements in pain and may reduce use of rescue medication. Two trials, 315 participants, low quality evidence. The Vioxx comparison, 88 participants, came back very low quality. In the same review, cayenne cream cleared moderate quality and white willow bark cleared moderate quality. Devil's claw did not.

Nothing new had gone wrong. No trial was retracted. The ruler changed.

2019: a military panel says pass

Then a 2019 panel assessing nineteen dietary ingredients for chronic musculoskeletal pain in US Special Operations Forces personnel recommended against devil's claw. It recommended against willow bark too, while giving conditional recommendations to turmeric and to ginger as a food source (ginger as a dietary supplement got no recommendation either way). Meanwhile NIH's complementary health center still lands in the middle: limited evidence for modest short-term low back pain relief, moderate evidence for osteoarthritis of the spine, hip and knee.

Four bodies, one plant, four answers. That is not a scandal, it is what happens when the underlying trials are small, mostly European, mostly short, and run by overlapping groups of people. Worth saying plainly: the second author of the 2004 review also authored or co-authored five of the twelve trials it graded, including both trials holding up that strong rating. The Cochrane review's senior author disclosed having previously worked for a company that produced and sold ingredients under review. Neither fact makes the data fake. Both are the kind of thing that should make a reader slow down.

What the trials actually looked like up close

The numbers are smaller than the language wrapped around them. In the dose-comparison trial, the count of patients pain-free without rescue medication for five days of the final treatment week was 3 on placebo, 6 at 50 mg harpagoside, and 10 at 100 mg. It reached statistical significance at p = 0.027. It is also ten people.

The more interesting signal is the rescue medication. Against diacerein in 122 people with hip and knee flares, the devil's claw group did not beat the drug on pain scores or the Lequesne index. They simply reached for fewer painkillers, a mean of 21 diclofenac tablets versus 60. Against Vioxx in 88 people, the difference in effect was not statistically significant, but dropouts from adverse events ran 1 in the herb arm against 6 in the drug arm. Devil's claw did not win those trials. It mostly declined to lose them, and it did so with a lighter side-effect bill. For an achy knee that is not nothing, and it is also not a cure.

Mechanism, with an asterisk

In cell culture, harpagoside suppresses LPS-induced COX-2 and iNOS expression by blocking NF-kB activation. That is a coherent anti-inflammatory story, and it is also a petri dish. Harpagoside gets used as the standardization marker largely because it is measurable. The 2004 reviewers pointed out that the actual active principle has still not been identified, which means the industry is dosing the label and hoping the ingredient came along. That uncertainty is shared by most botanicals people stack for joints, boswellia included, and it is a reason to be curious rather than confident.

Safety, briefly and without drama

A 2008 systematic review of 28 clinical trials found the incidence of adverse events during devil's claw treatment was low, while noting that long-term safety data remain thin. NIH flags specific people who should not freelance here. Devil's claw may affect heart rate and blood pressure and may be harmful in people with heart disease or circulatory disorders. It may lower blood glucose, so anyone with diabetes should watch their numbers. People with gallstones or peptic ulcer disease should avoid it. If you take medication for blood pressure, blood sugar, or clotting, that conversation belongs with a clinician, not a blog post.

Where it actually sits

Devil's claw is a reasonable thing to try and a poor thing to expect miracles from. It is among the more heavily studied herbal analgesics and still grades low to moderate across the board, which is an honest place for a plant to be. European monographs assume a run of two to three months, not four days, so patience is part of the protocol. It shows up alongside the usual suspects in joint support formulas, though stacking evidence is not the same as adding it up.

The plant itself deserves a footnote. It grows wild in the Kalahari, and harvesters dig around the plant to take only the secondary tubers, leaving the mother tuber intact so it regrows for a future season. For many rural families in Namibia, that harvest is the household's only cash income for months at a stretch, and women make up a large share of the collectors. It is a supply chain where doing it correctly and doing it sustainably happen to be the same act.

One practical note that applies to every herb above: plant material loses its actives sitting in a warehouse. We source professional-grade product per order instead of keeping aging stock on a shelf, which is why our shipping is slower than the two-day reflex everyone is trained to expect. With an herb whose entire evidence base hinges on how much harpagoside actually survived the trip into the capsule, fresher is the whole argument.

This article is for education only. It is not medical advice, and nothing here is intended to diagnose, treat, cure, or prevent any disease. Talk to a qualified clinician before starting any supplement, especially alongside prescription medication.

Sources

1. Gagnier JJ, Chrubasik S, Manheimer E. Harpagophytum procumbens for osteoarthritis and low back pain: a systematic review. BMC Complement Altern Med. 2004;4:13.
2. Oltean H, Robbins C, van Tulder MW, et al. Herbal medicine for low-back pain. Cochrane Database Syst Rev. 2014;(12):CD004504.
3. NCCIH (NIH). Nutritional Approaches for Musculoskeletal Pain and Inflammation: What the Science Says.
4. Crawford C, Boyd C, Paat CF, et al. Dietary ingredients as an alternative approach for mitigating chronic musculoskeletal pain. Pain Med. 2019;20(6):1236-1247.
5. Vlachojannis J, Roufogalis BD, Chrubasik S. Systematic review on the safety of Harpagophytum preparations for osteoarthritic and low back pain. Phytother Res. 2008;22(2):149-152.
6. Chantre P, Cappelaere A, Leblan D, et al. Efficacy and tolerance of Harpagophytum procumbens versus diacerhein in treatment of osteoarthritis. Phytomedicine. 2000;7(3):177-183.
7. Huang TH, Tran VH, Duke RK, et al. Harpagoside suppresses lipopolysaccharide-induced iNOS and COX-2 expression through inhibition of NF-kappaB activation. J Ethnopharmacol. 2006;104(1-2):149-155.
8. Union for Ethical BioTrade. Devil's Claw: improved livelihoods and landscapes through responsible harvesting.