How It Works
Bottom Line: There is limited proof from clinical trials that devil's claw can reduce inflammation or relieve pain.
Devil's claw is a root extract. It has been studied to some extent in test tubes and in animals, but its biological effects in humans are still not sorted out. In laboratory animals, devil's claw extracts reduce inflammation and cause pain relief, and also acts as an antioxidant. One study showed possible benefits for relieving some forms of arthritis, however, another study showed that devil's claw is not as effective as drugs such as aspirin in reducing inflammation. In rats, different doses of devil's claw have different effects on the heart: low doses seem to cause reduced heart rate and increased strength of contraction, while high doses seem to weaken heart contractions and coronary blood flow. These effects have not been shown in humans.
Purported Uses
- To increase appetite
No scientific evidence supports this use.
- To treat gastrointestinal disorders
No scientific evidence supports this use. Devil's claw might increase acid production by the stomach.
- To reduce inflammation
Studies in animals show a weak anti-inflammatory activity, but studies in humans do not support this use.
- To relieve pain
Studies in animals suggest that devil's claw can relieve pain, but there is no proof from clinical trials that this effect occurs in humans.
- To treat osteoarthritis
Studies in animals suggest that devil's claw can reduce inflammation, but there is limited proof from clinical trials that this herb can treat osteoarthritis.
Research Evidence
Only a few clinical trials have tested the anti-inflammatory properties of devil's claw, with weak and conflicting results. More research is needed to test whether this herb is safe and effective.
Osteoarthritis:
75 patients with osteoarthritis of the hip or knee participated in a study of a supplement that includes Devil's Claw. Patients received the supplement for 12 weeks after which time measurements of their level of pain, stiffness and physical function were shown to decrease by about a quarter. Because the study was not randomized, it is unclear if these findings are significant or are rather the result of a placebo effect.
Warnings
- This product is regulated by the F.D.A. as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
Do Not Take If
- You are pregnant.
- You are taking antacids or H2 blockers (Devil's claw can increase the production of stomach acid and reduce the effectiveness of these medications).
- You are taking beta blockers or digoxin (Devil's claw might interfere with these medications).
- You are taking warfarin or other blood thinners (Devil's claw might increase the risk of bleeding).
Side Effects
- Diarrhea
- Slowed heart rate (bradycardia) is a potential side effect
- Upset stomach
Scientific Name
Harpagophytum procumbens
Common Name
Grapple plant, wood spider
Brand Name
Doloteffin ™
Clinical Summary
Derived from the root or tuber. Clinical studies reveal conflicting data about efficacy of devil's claw as an anti-inflammatory or analgesic. It has been thought that the iridoid glucosides may be responsible for activity, but they are not active when administered separately from whole root extract. The basis for chemical standardization is unknown. Analysis of commercial products reveals wide variance in chemical components. Limited side effects have been reported; diarrhea and bradycardia also occur (1). An open clinical study suggests that Devil's claw may benefit patients with osteoarthritis of the hip or knee (6). A systematic review of clinical trials suggests that it may also be effective in treating low back pain (7). Devil's claw increases gastric acid secretions and may interfere with the activity of antacids and histamine-2 blockers (e.g. ranitidine and famotidine) (3). Other possible drug interactions include increased activity of anticoagulants and cardiac and anti-arrhythmic drugs (1).
Purported uses
- Anorexia
- GI disorders
- Inflammation
- Muscle pain
- Osteoarthritis
- Pain
Constituents
- Iridoid glucosides: Harpagoside, harpagide and procumbide
- Phytosterols: B-sitosterol, oleanolic acid
- Flavonoids: Kaempferol and luteolin
- Phenolic acids
- Glycosidic phenylpropanoic esters: Verbascoside and isoacteoside
(1)
Mechanism of Action
In animal studies, an aqueous extract containing chiefly harpagoside showed significant dose-dependent anti-inflammatory and analgesic effects. Harpagoside is not implicated in the anti-inflammatory action, but, along with other constituents, it does appear to be involved in the peripheral analgesic properties. Devils claw also has antioxidant effects by scavenging both superoxide and peroxyl in a dose dependent manner
(5). The bitter iridoids are responsible for the use of the herb as a stomachic. In vitro and in vivo animal studies have shown some evidence that devil's claw might be cardioactive. Lower doses seem to cause bradycardia and increase the strength of contraction, and high doses seem to weaken heart contractions and coronary blood flow
(2).
Contraindications
Pregnancy
Adverse Reactions
Reported: Diarrhea, possible bradycardia. Dispepsia
(6).
Herb-Drug Interactions
Antacids / H2 Antagonists: Devil's claw may reduce efficacy due to increased production of stomach acid.
Beta blockers / Digoxin: Devil's claw may cause bradycardia and weaken heart contractions and coronary blood flow.
Anticoagulants: Devil's claw may have additive anticoagulant activity.
Literature Summary and Critique
References
