Are devil's claw and willow bark safe for joint pain?

Short answer: in the trials we could open, devil's claw and willow bark extracts were tested for short periods, mostly for low back pain and knee or hip osteoarthritis, and the adverse events reported were mostly minor. That is not the same as "safe for everyone". Both ingredients have cautions, willow bark is chemically related to aspirin, and the doses that were studied are specific amounts of a standardized extract, not "500 mg of root powder" on a label. This article is general information, not medical advice.

We audit offers, so we looked at the research first and then at how four joint supplements in our reviews print these two ingredients on the label.

What do the trials of devil's claw and willow bark show?

The most useful summary we found is a 2014 Cochrane review of herbal medicine for low back pain. It included 14 randomized trials with 2,050 participants. For devil's claw (Harpagophytum procumbens), the reviewers wrote that daily doses standardized to 50 mg or 100 mg of harpagoside "may be better than placebo" for short-term pain and may reduce the use of rescue medication. That finding came from two trials with 315 participants and was graded low-quality evidence.

For white willow bark (Salix alba), daily doses standardized to 120 mg or 240 mg of salicin were judged "probably better than placebo" for short-term pain, based on two trials with 261 participants and moderate-quality evidence. Note the wording: short-term, low back pain, and a specific standardized dose.

A separate 2009 systematic review of willow bark for musculoskeletal pain found moderate evidence for low back pain, conflicting results in osteoarthritis, and no significant effect in one small, underpowered rheumatoid arthritis study. Every trial in it used an ethanol extract at up to 240 mg of salicin a day, for up to six weeks, and it reported only minor adverse events.

A 2009 review of herbal products for osteoarthritis found that several studies of devil's claw reported favorable effects on pain, while two studies of a willow bark extract gave disparate results. Its own conclusion is the one to remember: the effectiveness of none of the herbal products reviewed was proven beyond doubt.

What does "standardized" mean on a supplement label?

A plant contains many compounds, and the amount varies with the crop, the part used and the extraction method. Researchers therefore dose by a marker compound. For devil's claw the marker in the trials above was harpagoside. For willow bark it was salicin. When a trial says "100 mg of harpagoside a day", that is the amount of one compound in the extract, not the weight of the capsule contents.

This is why "500 mg of devil's claw root powder" and "100 mg of harpagoside" are not interchangeable. The first number tells you how much dried root went into the capsule. The second tells you how much of the studied compound you swallow. Without a percentage on the label, you cannot convert one into the other, and so you cannot compare the product with the trials.

The same logic applies to ratios such as "4:1 extract". A 4:1 ratio describes how much raw plant went into the extract. It does not say how much salicin the extract contains.

How do four joint supplements print these ingredients?

Here is what the label data in our reviews shows. We audit the offer, we do not test the pills, and the numbers below are what each sales page or order form prints.

Product	Devil's claw	Willow bark	Harpagoside or salicin stated?
Joint Glide	500 mg root powder	150 mg extract	No
Serrasoothe	Amount not stated	Amount not stated	No
VitaMotion	Not listed	Amount not stated	No
Flexafen	Not listed	4:1 extract, amount not stated	No

Joint Glide is the most open of the four: its label gives a milligram amount for every ingredient, which our review credits as unusual for the category. But its 500 mg of devil's claw has no harpagoside percentage, and its 150 mg of willow bark extract has no salicin percentage. Compared with the 50 to 100 mg of harpagoside and 120 to 240 mg of salicin used in the Cochrane trials, we cannot say whether it reaches those amounts.

The other three print no amount for willow bark at all. Serrasoothe also lists devil's claw with no amount. If you want the full picture, the joint and mobility category shows how many joint formulas hide doses behind a long ingredient list, and our review method explains how we compare label amounts with studied doses.

Why is willow bark treated like aspirin?

Willow bark contains salicin and salicylic acid, according to the LactMed database. A 2012 pharmacy article on aspirin's history notes that aspirin's origins lie with willow bark. MedlinePlus says aspirin belongs to a group of medicines called salicylates, and its aspirin page lists several cautions: ask a doctor before giving aspirin to a child or teenager because of Reye's syndrome, tell your doctor about ulcers, bleeding problems or kidney or liver disease, and tell your doctor if you are pregnant or breast-feeding.

Those are aspirin warnings, not willow bark warnings, and a willow extract delivers salicin in a different form and amount. The point is practical: a product that contains a salicylate-related plant is not a "gentle, risk-free" alternative just because the plant is natural. The LactMed drug database says willow bark is best avoided during breastfeeding, and notes that safer drugs are available for pain and fever.

For devil's claw, the sources we could open describe short trials with few reported problems, but the Cochrane authors graded the evidence low quality, and we found no long-term safety data in the pages we opened. That gap is a reason to ask, not a reason to assume.

Who should ask a doctor or pharmacist first?

The FDA advises people to talk to a doctor, pharmacist or other health care professional before buying or using any dietary supplement, noting that supplements may interact with medicines or with other supplements. Because willow bark is related to aspirin, these groups have particular reasons to check:

• People who take aspirin, other pain relievers, blood thinners or any prescription medicine.
• People with ulcers, stomach bleeding history, bleeding disorders, asthma triggered by aspirin, or kidney or liver disease.
• People who are pregnant, planning pregnancy or breastfeeding.
• Parents considering any salicylate product for a child or teenager.

Bring the bottle or a photo of the label. Pharmacists can only help if they see every ingredient and every amount, including the ones the page does not print.

A checklist before you buy a joint formula with these herbs

1. Find the Supplement Facts panel. If the page shows no panel, treat that as missing information.
2. Look for harpagoside for devil's claw and salicin for willow bark, given as a percentage or an amount.
3. Compare with the studied range: 50 to 100 mg harpagoside and 120 to 240 mg salicin a day.
4. Check how many capsules the daily dose needs, and what that does to the monthly price.
5. Read the refund terms on the order form, not only on the sales page. Our ClickBank refund guide explains how those claims work.
6. Show the label to a pharmacist if you take any medicine.

FAQ

Are devil's claw and willow bark safe for joint pain?

The trials we opened were short, up to about six weeks for willow bark, and reported mostly minor adverse events. Safety over months or years is not established in those sources, and willow bark carries salicylate-type cautions. Ask a doctor or pharmacist first, especially if you take medicine.

Is willow bark the same as aspirin?

No, but they are related. Willow bark contains salicin, and aspirin's origins lie with willow bark. A supplement is not a regulated drug at a known dose, so you cannot assume it behaves like an aspirin tablet.

How much devil's claw is in a joint supplement?

It varies and is often not printed. Joint Glide lists 500 mg of root powder, while Serrasoothe lists devil's claw with no amount. The Cochrane trials used extracts standardized to 50 to 100 mg of harpagoside a day.

Does the FDA approve joint supplements?

No. Under the law that governs supplements, the FDA does not approve them before they are sold. A label amount is the maker's statement, which is why we compare it with the research instead of taking it on faith.