Devil's Claw

Harpagophytum procumbens

Efficacy

• Indications with possible efficacy:
  Osteoarthritis and musculoskeletal pain (popular use)
• Indications with possible, but poorly documented efficacy:
  Indigestion
  Loss of appetite
  
• Indications with no proof of efficacy:
  Arteriosclerosis
  Arrhythmia
  Gout
  High blood pressure
  Menstrual problems
  Myalgia
  Rheumatoid arthritis
  Wounds (topically)

Security

• Risk of Drug Interactions: Moderate
• Adverse Effects: Not Frequent

Description

Part of the plant used: tuberised secondary root

The name of the plant comes from the appearance of the fruit, which is covered by hooks meant to attach to the fur of passing animals thus spreading the seeds in the environment.

Only roots are of interest and harpagoside seems to be the active ingredient. Devil's claw root is usually standardized to 3% iridoid glycosides or 2% harpagoside.

Direction of use

• Indigestion:
  Devil's claw may increase bile volume, which could improve the digestion of lipids.

  Used doses: 500 mg of root 3 times a day.

• Osteoarthritis and musculoskeletal pain:
  Devil's claw appear to have a mild effect against pain, which is most probably insufficient to relieve severe pain, but could be useful as an adjunct to other therapies.

  Used doses: 1.5 to 3 grams of root's powder per day or capsules containing a daily amount of 50 to 100 mg of harpagoside.

• Loss of appetite:
  Devil's claw seems to slightly increase appetite.

  Used doses: 500 mg of root 3 times a day. For this indication, decoction or liquid extract would be more effective and enteric-coated tablets should be avoid.

There is insufficient reliable information to conclude that devil's claw is effective in any other indications, including topical application as an analgesic. A well-designed study would have showed that devil's claw is not effective against arthritis.

Precautions

• Side effects
  Devil's claw does not appear to be associated with any severe toxicity. The most common adverse effects are diarrhea, nausea, vomiting and abdominal pain. Severe headaches, buzzing in the ears, marked loss of appetite and loss of taste are also possible side effects but infrequent. The safety of long-term use remains undetermined.
• Contraindications
  Devil's claw is contraindicated in patients with gastric and duodenal ulcers because it increase the production of gastric acid. It should be used with great caution in individuals with suspected gallstones (biliary lithiasis). If diabetes, monitor for blood sugar because devil's claw may lower glycemia. Also, avoid if active bleeding and 2 weeks before a surgery or dental procedure.
• Interactions
  Try to avoid if you are already taking medications for arrhythmia or blood thinner (warfarin, aspirin, nonsteroidal anti-inflammatory, etc.)
• Pregnancy and lactation
  Because the product may cause uterine contractions, it is contraindicated during pregnancy. Since there is no safety data available concerning its use during breast-feeding, lactating women should not use devil's claw.

Clinical Notes

• Devil's claw seems to be well tolerated for daily use up to a year.

Warning

In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.

Medicinal plant contents vary naturally from plant to plant - just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.

For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.

References

1. Blumethal M et al. The Complete German Commission E monographs, 1998
2. Natural Medicines Comprehensive Database, Therapeutic Research Faculty, 2010
3. Lininger S. et Al. The Natural Pharmacy, Prima Health, 1998
4. Barnes J. et Al. Herbal Medicines, 2nd Edition, Pharmaceutical Press, 2002
5. Pierce Andrea, Practical Guide to Natural Medicines, 1999
6. Passeportsanté.net. Griffe du diable. www.passeportsante.net
7. Rotblatt M. and Ziment I. Evidence-Based Herbal Medicine, Hanley & Belfus, 2002
8. Natural Therapeutics Pocket Guide, 2000-2001
9. The Review of Natural Products, 6e édition, 2010
10. Health Canada, Natural Products Database