Natural Products

Cat's Claw

Uncaria tomentosa

Efficacy

• Indications with proven efficacy:
  None
• Indications with possible, but poorly documented efficacy - the use of this product cannot be recommended:
  Osteoarthritis and rheumatoid arthritis
• Also used for these other indications, but with no proof of efficacy:
  Cancer
  Contraception
  Diverticulitis
  Gastritis
  Hemorrhoids
  Immune system stimulant
  Inflammation
  Intestinal inflammatory disease
  Peptic ulcers

Security

• Risk of Drug Interactions: Low
• Adverse Effects: Rare

What is it?

Cat's claw is indigenous to the Tropics, especially to South-East Asia and South America; it is part of the vine family. Its name comes from the fact that there are small claw-like thorns at the junction of the stem and leaf. It is largely used by South American healers who claim that its potency can restore health. Every part of the plant is used: leaves, roots or bark. It is believed to have anti-inflammatory, antimutagenic, anticancer and antioxidant properties, however its mechanism of action is unknown. Cat's claw is thus used to treat inflammation, infections and cancer. Its activities are linked to the plant's many alkaloids which appear to have varying properties. A few small human investigations have found cat's claw to be somewhat useful in the treatment of HIV (AIDS).

Cat's claw is available in tablets or capsules and sometimes in combination with other products.

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) or homeopathic medicine number (DIN-HM) 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 plants content varies 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 http://www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.

Does it work?

There is no evidence that cat's claw is effective in any indication. However it is used to treat certain conditions in which it could be of some benefits:

• Osteoarthritis and rheumatoid arthritis:
  Studies on animals and in laboratories have shown anti-inflammatory activity. Dose recommendations vary greatly from one source to another. Most people use from 500 to 1000 mg of cat's claw (capsules and tablets contain the raw herb), one to three times a day. Various extracts are also used.

There is insufficient reliable information to conclude that cat's claw is effective in any other indication.

Is it safe?

• Based on its long history, cat's claw does not appear to be associated with any toxicity. The use of large doses may cause diarrhea, and some individuals may be more sensitive to this side effect. Cat's claw may cause headache, vomiting, hypotension and dizziness.
• Since there is no safety data available concerning its use during pregnancy and breast-feeding, pregnant and lactating women should not take cat's claw. Because of its potential contraceptive effect, women who wish to become pregnant should discontinue its use.
• Using cat's claw in combination with antihypertensive agents may increase the risk of hypotension. Cat's claw may interfere with immunosuppressant therapy or autoimmune diseases (multiple sclerosis, systemic lupus erythematosus) because of its immunostimulating properties. Before taking cat's claw, check with your pharmacist to make sure that there are no interactions with your regular medication.

Clinical notes

• Cat's claw has been used by Peruvian and other South American healers for a very long time. They have used it to treat some types of gastrointestinal problems, tumors, cancer and as a contraceptive. Cat's claw does not appear to be associated with any severe toxicity. Current reliable information leads us to believe that it may be effective in some of its proposed uses, but further research is needed to determine its exact value.

References

1. Natural Medicines Comprehensive Database, Therapeutic Research Faculty, 2007
2. Peirce, Andrea. Practical Guide to Natural Medicines, APha, 1999
3. Facts & Comparisons, The Lawrence review of natural products, 1998
4. Chandler, Frank. Herbs – Everyday Reference for Health Professionals, CphA – CMA, 2000
5. Passeportsanté.net. Griffe de chat. http://www.passeportsante.net
6. Barnes J. et Al. Herbal Medicines, 2nd edition, Pharmaceutical Press, 2002
7. Rotblatt M. et Ziment I. Evidence-Based Herbal Medicine, Hanley & Belfus, 2002