Cat’s claw is a medicinal herb traditionally used to stimulate the immune system. Research has shown it may boost immune function, reduce inflammation, and even help with chemotherapy. Read on to discover the potential health benefits and adverse effects associated with this herb.
Cat’s claw (Uncaria tomentosa) is a medicinal plant that grows in the Amazonian rainforest and other tropical areas in Central and South America. The use of the herb dates back to the Inca civilization. Indigenous cultures of South America used cat’s claw for inflammation, cancer, viral infections, ulcers, and to stimulate the immune system [1, 2].
It gets its name from its thorns, which resemble the claws of cats.
The two different types of cat’s claw contain different active compounds and have different medicinal properties. Uncaria tomentosa contains more pentacyclic oxindole alkaloids (POAs), while U. guianensis is richer in tetracyclic oxindole alkaloids (TOAs) [3, 4].
TOAs act on the central nervous system (brain and spinal cord), whereas POAs affect the immune system .
TOAs cancel out the effects of POAs. Therefore it is important when purchasing and consuming cat’s claw extracts to be sure that they have been tested for TOA and POA levels .
Differences between the two types are conveyed in the chemical structure. Pentacyclic alkaloids are found in the vine bark while tetracyclic alkaloids are found in the leaves and stem of the plant [6, 7].
Cat’s claw is rich in three major groups of chemical compounds: alkaloids, terpenoids, and flavonoids .
Specific compounds found in cat’s claw include:
- Mitraphylline: an alkaloid usually found in older leaves. It has potential anticancer effects, causing cell death in sarcoma and breast cancer cells [4, 8].
- Rhynchophylline: an alkaloid isolated from the bark. It may help with convulsions, lightheadedness, numbness, and hypertension [9, 10].
- Isopteropodine: an alkaloid isolated from the leaves. It has antimicrobial properties against (Gram-positive) bacteria [9, 11].
- Uncarine (C, D, and E): a family of alkaloids found in the leaves. They have potential anti-cancer properties, inducing cell death in leukemia cells [4, 12].
- Hirsutine: an alkaloid found in the young leaves. It has antihypertensive properties, relaxing blood vessels and reducing overall blood pressure [4, 13].
- Uncaric acid: a triterpene extracted from the bark. It may be effective against Mycobacterium tuberculosis (H37Rv strain) [14, 15].
- Quinovic acid: an acid triterpene compound extracted from the bark. It may reduce heart rate [16, 17].
- Quinic acid has antioxidant properties, enhances DNA repair, and has neuroprotective effects in the brain [18, 19, 20].
- Procyanidins: a flavonoid (phenolic compounds found in the leaves, stems, bark, and wood of U. tomentosa). It has antioxidant, anti-inflammatory, and anticancer properties [21, 22].
- Decreases inflammatory molecules TNF-α and NF-κB [23, 24, 25].
- Blocks the release of iNos, an enzyme that creates free radicals as part of the immune response .
- Blocks the release of COX-1 and COX-2, enzymes that play crucial roles in inflammation and pain [27, 28].
Cat’s claw’s anti-inflammatory effects have been commonly used to treat both rheumatoid arthritis and osteoarthritis .
In a clinical trial on 40 rheumatoid arthritis patients, cat’s claw combined with conventional treatments (sulfasalazine/hydroxychloroquine) reduced tender and painful joints .
In another trial of 45 people with knee osteoarthritis, one week of cat’s claw reduced pain associated with activity. In another trial on 95 people, a dietary supplement with 300 mg cat’s claw and 1500 mg maca improved joint pain, stiffness, and function as effectively as the more common supplement glucosamine sulfate .
Cat’s claw extract increased IGF-1 levels in human cartilage cells, which might help to maintain cartilage health and prevent cartilage breakdown. In animal and cell-based studies, cat’s claw blocked IL-1β and other inflammatory molecules that suppress IGF-1 production [32, 33, 34].
The different compounds in cat’s claw supposedly act together to achieve these effects .
Although limited, the existing evidence suggests that cat’s claw may help with the symptoms of both rheumatoid arthritis and osteoarthritis. You may discuss with your doctor if it could be useful as an adjuvant therapy in your case. Never take cat’s claw in place of what your doctor recommends or prescribes for arthritis.
In a study of 31 volunteers with cold sores (herpes labialis), cat’s claw was more effective in reducing symptoms such as swelling, skin reddening, and pain compared to prescription antiviral drug Acyclovir .
In a cell-based study, cat’s claw extract prevented the spread of the herpes virus by preventing it from attaching to cells .
In another trial on 261 people, immunostimulation with a natural product containing cat’s claw and other herbal extracts reduced the incidence of anal warts (caused by infections with the human papillomavirus) after a surgical procedure .
Cat’s claw also prevented immune cells from being infected with dengue virus and reduced inflammatory cytokines TNF-alpha and IFN-alpha .
Although the results are promising, two clinical trials and some animal and cell-based research cannot be considered sufficient evidence to support the use of cat’s claw for viral infections. Further clinical research is needed.
In a study of 40 breast cancer patients undergoing chemotherapy, 300 mg cat’s claw extract prevented a decrease in white blood cells (neutropenia) and repaired DNA damage. However, the same dose was ineffective in another trial on 43 people with colorectal cancer [42, 43].
In a clinical trial on 51 people with advanced cancer, cat’s claw reduced fatigue and improved quality of life .
In rats who received chemotherapy, cat’s claw increased white blood cell count and helped repair damaged DNA .
Cat’s claw also stimulates the growth of progenitor cells in mice, which can replace damaged cells and reduce the damaging effects of chemotherapy .
Again, 3 clinical trials (with mixed results) and some animal research are insufficient to claim that cat’s claw may help fight cancer. Larger, more robust clinical trials are needed.
Cat’s claw can cleanse the digestive tract and is claimed to help treat inflammatory gut disorders including :
In a clinical trial on 50 people with gum inflammation, a gel with cat’s claw was as effective as an antifungal (miconazole) at reducing the counts of infectious yeasts .
Inflammation of the gut is also caused by toxic free radicals (peroxynitrite). Cat’s claw broke down free radicals and reduced cell death caused by gut bacterial toxins .
While only a small trial investigated cat’s claw for gum inflammation, its effects on inflammation of the digestive system have only been tested in animals. Further clinical research is required to confirm these preliminary findings.
In a small trial on 23 healthy volunteers, a cat’s claw extract enhanced the immune effects of a vaccine against pneumococcal infections. The extract increased the relative abundance of immune cells (lymphocytes) and prolonged the antibody titer response of the vaccine .
Again, only a small clinical trial and some animal and cell-based research have investigated this potential benefit of cat’s claw. More clinical trials on larger populations are warranted.
Two different traditional Chinese medicines with cat’s claw and other herbs (Jiangzhuo Qinggan and Qian Yang He Ji) lowered blood pressure in clinical trials on almost 300 people. However, another remedy combining cat’s claw and potato orchid (Gastrodia) was ineffective and used as the negative control in another trial on 79 people [55, 56, 57].
Cat’s claw contains a compound called hirsutine that reduces blood pressure. It acts as a calcium channel blocker in the heart and blood vessels, which slows down the heart rate and relaxes the blood vessels [4, 13, 58].
Because the only clinical trials tested herbal mixes containing cat’s claw and other extracts (with mixed results), we cannot establish if the effects observed were due to this specific ingredient, More clinical trials using cat’s claw alone are needed to shed some light on this potential use.
No clinical evidence supports the use of cat’s claw for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.
Cat’s claw has been traditionally used to treat diabetes .
Procyanidins and other polyphenols in cat’s claw scavenged and remove oxidative radicals in cell-based studies .
Cat’s claw also blocked the production of the inflammatory cytokine TNF-α and prevented cell death .
This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects.
Call your doctor for medical advice about side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.
- Upset stomach
- Skin rash
Pregnant women should avoid using cat’s claw because of the herb’s potential to cause abortion .
Because cat’s claw seems to enhance the immune response by increasing the activity of immune cells, this supplement may increase the symptoms of autoimmune disorders. People with autoimmune conditions should be especially cautious with cat’s claw and never take it without discussing it with their doctors .
Cat’s claw decreased molecules that activate clotting (IL-1α, 1β, 4, 17, and TNF-α). People with blood clotting disorders or on blood thinners should avoid cat’s claw to reduce the risk of bleeding and bruising [35, 41].
When cat’s claw was used in combination with some HIV treatments like protease inhibitors (atazanavir, ritonavir, and saquinavir), it increased their toxicity .
Few high-quality clinical trials with cat’s claw have been conducted in humans. More studies are needed to confirm its health benefits.
Cat’s claw was sometimes tested as part of multi-herbal complexes, making its specific contribution to the effects observed difficult to estimate.
Because cat’s claw is not approved by the FDA for any conditions, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if cat’s claw may be useful in your case and which dose you should take.
Clinical trials have used between 80 – 350 mg of cat’s claw extract. These extracts usually contained a certain amount of pentacyclic oxindole alkaloids, rather than tetracyclic oxindole alkaloids.
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Several users reported satisfactory results when using cat’s claw for arthritis, digestive inflammation, and infections.
A doctor claimed using cat’s claw on 150 patients during the last 4 years and obtaining better results than with any other available products.
One user noted that cat’s claw increased the severity of their headache and fatigue, which they linked to a die-off effect.