Cat's Claw
Cat’s claw, uña de gato, uncaria tomentosa, uncaria guianensis, saventaro, C-Med-100®, Activar AC-11®
Description
Cat's claw (Uña de gato) refers to a number of plants with curved thorns that resemble the claws of a cat. This plant type (genus Uncaria) grows in southeast Asia and the rain forests of South America, especially Peru. The two Latin American species, guianensis and tomentosa, are often confused with each other, but have different uses. One species, Uncaria guianensis, has traditionally been used for wound healing. The other species, Uncaria tomentosa, has been used for a wide variety of traditional and non-traditional medicinal effects. (Traditional uses by native priests have been to treat anxiety.)
Research
Laboratory investigations of Uncaria tomentosa have focused upon immune and cancer related effects such as repair of DNA and recovery from the effects of cancer treatment by cells of the blood and lymph system. One chemical subtype of Uncaria tomentosa had supportive effects upon lymphocytes, but the other chemical sub-type had opposite effects.
A randomized trial for patients with rheumatoid arthritis reported benefits for those who were treated with Uncaria tomentosa, but both groups of patients were also receiving standard arthritis medicines so this study mainly demonstrates safety.
Two unpublished, non-peer reviewed single cohort studies in patients with cancer reported positive effects; however, these findings have not been confirmed in a randomized, comparative study or published in peer-reviewed scientific literature.
Dose
The dose for tea is typically 20 to 30 grams of bark in 480 mL (one quart) of water that is boiled until reduced to 1/3 of volume (about 45 minutes), cooled to room temperature and then sipped two to three times daily. (Five grams per 100 mL (3.3 oz) for 20 minutes or 20 grams per 1000 mL for 30 minutes have also been described.)
The most effective and safe medicinal dose is not clear. Oral doses used in studies have ranged from 100 to 1000 mg a day in divided doses. Tinctures of one to two ml (20-30 drops) have been used on the skin up to three times per day.
Because of differences in types and potency of extracts, it is important to follow directions on labels and try to stay with one consistent brand/manufacture.
How it is taken
Cat's claw has been sipped as tea, swallowed in capsules or applied to the skin as a tincture (alcoholic extract) or cream.
Side effects
Mild rash, diarrhea, drowsiness and hypotension (low blood pressure) have been reported. Drowsiness and low blood pressure are more likely to occur when taking extracts with a higher proportion of tetracyclic alkaloids.
Cautions
Major risks of toxicity occur if the wrong plant is harvested, sold and consumed. One look-alike plant (Acacia greggii) that grows along the border between Texas and Mexico may be poisonous, as some of these shrubs are believed to contain cyanide.
Two chemical subtypes within Cat’s Claw counteract each other if taken together.
Cat’s Claw has the potential to interact with other medications. It may block platelets from forming clots, so it should never be taken with any blood thinners such as aspirin. It may also interact with hormones, insulin, vaccines and other drugs.
Contraindictions
Do not take or give Cat’s Claw if:
- Pregnant or breastfeeding (Cat’s claw has been used to induce abortions.)
- Children are less than three years old (unknown effects upon immature immune systems)
- Autoimmune disease exists, such as lupus or multiple sclerosis (Renal failure has been reported in one patient with lupus.)
- You have had organ or bone transplant (risk of organ rejection)
- Taking blood thinners, hormones, insulin, vaccines or other drugs
Important Advice
To avoid potential interactions, be sure to let your health care provider know if you use this or any other type of complementary therapy.
More in-depth information about cat's claw therapy is provided in the Detailed Scientific Review.
Authors and Editors
Initial authorship:
Nancy C. Russell, Dr.P.H., senior health education specialist, Integrative Medicine Program Education Component
Reviewers and editors:
Judith A. Smith, Pharm.D., FCCP, BCOP, assistant professor, Gynecologic Oncology
Lorenzo P. Cohen, Ph.D., director, Integrative Medicine Program
Stephen P. Tomasovic, Ph.D., senior vice president for academic affairs