Cat's Claw Standardized [Discontinued] by Nature's Way

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). Although there is interest in using oral cat's claw for allergic rhinitis, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Alzheimer disease. Although there is interest in using oral cat's claw for Alzheimer disease, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Asthma. Although there is interest in using oral cat's claw for asthma, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Atopic dermatitis (eczema). Oral cat's claw has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that using a specific spray combination of cat's claw (Uncaria tomentosa) 1% and Rhealba oat plantlet extract 0.25% (Pierre Fabre Dermo Cosmetique) up to 6 times daily for 22 days subjectively reduces skin symptoms of atopic dermatitis when compared with baseline (103170). The validity of this finding is limited by the lack of a comparator group. Additionally, it is not clear whether the results are due to cat's claw, oat extract, spray excipients, or the combination.
• Cancer. It is unclear if oral cat's claw is beneficial for improving quality of life in patients with cancer. Details: Preliminary clinical research in patients with terminal advanced solid tumors shows that taking a specific cat's claw (Uncaria tomentosa) extract, standardized to 5% mitraphylline, 100 mg three times daily for at least 8 weeks improves quality of life, social functioning, and fatigue when compared with baseline (92502). The validity of this finding is limited by the lack of a comparator group.
• Chronic fatigue syndrome (CFS). Although there is interest in using oral cat's claw for CFS, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Denture Stomatitis. It is unclear if oral cat's claw is beneficial for the treatment of denture stomatitis. Details: In patients with denture stomatitis, a small clinical trial shows that topical application of 2.5 mL of a gel containing cat's claw (Uncaria tomentosa) 2% to the base of dentures three times daily after meals for one week is as effective as miconazole 2% for improvement of symptoms. However, these treatments were also similarly effective to placebo (105186).
• Diarrhea. Although there is interest in using oral cat's claw for diarrhea, there is insufficient reliable information about the clinical effects of cat's claw for this purpose.
• Hemorrhoids. Although there is interest in using oral cat's claw for hemorrhoids, there is insufficient reliable information about the clinical effects of cat's claw for this purpose.
• Human papillomavirus (HPV). Oral cat's claw has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking three tablets of a specific combination supplement containing cat's claw, echinacea, andrographis, grapefruit, papaya, and pau d'arco daily for one month reduces the recurrence of anal condylomata in patients following surgical removal of anal condylomata. After one month, recurrence was 4% in the supplement group compared with 18% in the control group; after six months the recurrence rates were 7% and 27%, respectively (20073). However, the validity of these findings is limited due to poor study methodology. Additionally, it is unclear if this effect is due to cat's claw, other ingredients, or the combination.
• Inflammatory bowel disease (IBD). Although there is interest in using oral cat's claw for ulcerative colitis and Crohn disease, there is insufficient reliable information about the clinical effects of cat's claw for these conditions.
• Osteoarthritis. It is unclear if oral cat's claw is beneficial for osteoarthritis. Details: A small clinical trial shows that taking a specific freeze-dried cat's claw (Uncaria guianensis) extract 100 mg daily orally relieves knee pain related to physical activity within one week of treatment, but does not decrease pain at rest or knee swelling (7317). Other clinical research shows that taking a specific combination supplement (Reparagen) 1800 mg twice daily for 8 weeks can reduce pain and stiffness, improve function, and reduce the need to use rescue medication similarly to glucosamine sulfate. This specific combination supplement contains cat's claw (Vincaria) 300 mg and maca (RNI 249) 1500 mg per dose (33614). It is unclear if this effect is due to cat's claw, maca, or the combination. Additionally, it is unclear how these outcomes compare to the use of placebo.
• Osteoporosis. Although there is interest in using oral cat's claw for osteoporosis, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Psoriasis. Oral cat's claw has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that using a specific spray combination of cat's claw (Uncaria tomentosa) 1% and Rhealba oat plantlet extract 0.25% (Pierre Fabre Dermo Cosmetique) up to 6 times daily for 22 days subjectively reduces skin symptoms of psoriasis when compared with baseline (103170). The validity of this finding is limited by the lack of a comparator group. Additionally, it is not clear whether the results are due to cat's claw, oat extract, spray excipients, or the combination.
• Rheumatoid arthritis (RA). It is unclear if oral cat's claw is beneficial for RA. Details: A small clinical trial shows that taking a specific cat's claw (Uncaria tomentosa) extract 20 mg three times daily orally, containing 14.7 mg/gram pentacyclic oxindole alkaloids and no tetracyclic oxindole alkaloids, appears to modestly improve symptoms of RA. When taken orally in combination with sulfasalazine or hydroxychloroquine for 24 weeks, cat's claw seems to reduce the number of painful joints when compared with placebo. However, there is no effect on the number of swollen joints, pain, or the patient assessment of disease (8661). More evidence is needed to rate cat's claw for these uses.

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POSSIBLY SAFE ...when used orally, short-term. A specific freeze-dried aqueous extract seems to be safe when used in doses of 100 mg daily for up to four weeks (7317). Another extract of cat's claw, free of tetracyclic oxindole alkaloids, seems to be safe when used in doses of 60 mg daily for up to 24 weeks (8661). There is insufficient reliable information available about the safety of cat's claw when used topically.

PREGNANCY: POSSIBLY UNSAFE
when used orally. There is concern that cat's claw might be unsafe based on its traditional use as a contraceptive (12); avoid using.

LACTATION:
Insufficient reliable information available; avoid using.

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ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, cat's claw may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Cat's claw contains rhynchophylline and isorhynchophylline. Animal research suggests that these alkaloids can inhibit platelet aggregation (40220,40276). This interaction has not been reported in humans.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking cat's claw with antihypertensive drugs might increase the risk of hypotension.  Details Cat's claw contains rhynchophylline. In vitro and animal research suggests that rhynchophylline can lower blood pressure (40255,40268,40276). This interaction has not been reported in humans.

CALCIUM CHANNEL BLOCKERS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking cat's claw with calcium channel blockers might increase the risk of hypotension.  Details Cat's claw contains various alkaloids, including rhynchophylline, isorhynchophylline, corynoxeine, and isocorynoxiene. Animal research suggests that these alkaloids can lower blood pressure by acting as calcium channel blockers (40255,40268). This interaction has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cat's claw might increase the levels and adverse effects of drugs metabolized by CYP3A4.  Details In vitro research shows that cat's claw can inhibit CYP3A4 enzymes (6450,25522). In one case report, a patient taking cat's claw (at an unspecified dose) experienced increased serum levels of atazanavir, ritonavir, and saquinavir, all of which are CYP3A4 substrates. Levels returned to normal 15 days after discontinuation of the cat's claw supplement, suggesting inhibition of CYP3A4 by cat's claw (25522).

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General ...Orally, cat's claw seems to be well tolerated. Topically, no adverse effects have been reported; however, a thorough safety evaluation has not been conducted.
Serious Adverse Effects (Rare):
Orally: Kidney injury.

Dermatologic ...Orally, itchy skin lesions occurred rarely in one clinical study. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Gastrointestinal ...Orally, cat's claw has been reported to cause nausea, vomiting, abdominal pain, abdominal distention, constipation, epigastric pain, and diarrhea in 2% to 10% of individuals in one clinical study. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Hematologic ...In one clinical study of oral cat's claw, anemia occurred in 12% of patients and leukopenia and thrombocytopenia each occurred in 2% of patients. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Neurologic/CNS ...In one clinical study of oral cat's claw, headache occurred in 2% of patients, fatigue and insomnia each occurred in 4% of patients, and neuropathy occurred in 8% of patients. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Renal ...Several case reports link cat's claw to kidney injury. A patient with systemic lupus erythematosus developed acute kidney failure after taking cat's claw, which improved upon its discontinuation (40279). Another patient with a history of cancer who consumed keto-diet shakes containing cat's claw developed biopsy-confirmed acute interstitial nephritis requiring treatment with prednisone. The patient's serum creatinine normalized three months later after stopping the shake (111737). A separate case cited nephrolithiasis linked to a product containing cat's claw (Digestive Advantage and FlexProtex), likely due to its excipient silica dioxide. The patient's symptoms were reduced after discontinuation (40244).
A clinical study also reported a mild serum creatinine increase in 6% of patients taking oral cat's claw, but causality remains unclear due to the advanced disease states of the participants. No placebo was used in the study (92502).

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