About Herbs

Bottom Line: Clinical trials show that capsaicin is an effective treatment for some types of nerve pain and arthritis, but it does not work for everybody. It takes at least four weeks to start working.

Capsaicin is the pungent ingredient in hot chili or cayenne peppers. Out of the various uses for capsaicin, the topical use to treat pain has been studied most extensively. When applied to the skin, capsaicin is absorbed and is thought to block pain fibers by preventing the transmission of pain signals to the brain. This effect does not occur immediately, and requires topical application four or five times daily for a period of at least four weeks to be effective. Because capsaicin's irritating and pungent nature, it is thought to induce tumors, however mouse studies have shown that this in not the case.

Nerve pain (neuropathy):
A randomized, controlled trial using capsaicin cream to treat pain from distal symmetrical peripheral neuropathy (DSPN), a pain syndrome associated with HIV disease. Twenty-six patients were randomly assigned to apply either capsaicin cream or a placebo cream to their affected hands and feet. After one week, patients using capsaicin reported worse pain than the placebo group, and more patients using capsaicin dropped out of the study. After four weeks of using the creams, both groups of patients reported similar levels of pain and quality of life, indicating that capsaicin is no better than placebo in relieving pain from distal symmetrical peripheral neuropathy.

Cancer patients who had post-surgery neuropathic pain were enrolled in a clinical trial to assess the effectiveness of capsaicin. Ninety-nine patients randomly received either capsaicin cream for eight weeks followed by a placebo cream for eight more weeks or vise versa. Although many patients reported skin burning and redness while using the capsaicin cream, they also reported that their neuropathic pain decreased an average of 50% after eight weeks of using capsaicin. In addition, patients chose capsaicin over placebo by a margin of 3 to 1.

Urinary symptoms:
In a case reports series, six patients benefited from an intra-bladder injection of capsaicin, showing improved urinary symptoms including reduced urinary urgency. Large clinical trials are needed to confirm this effect.

Arthritis:
A randomized controlled trial studied the effects of topical capsaicin cream on painful hand joints in 21 patients with rheumatoid arthritis or osteoarthritis. Patients using capsaicin noted a local burning sensation, but also reported reductions in pain and tenderness as compared to the placebo group. This was true only in patients with osteoarthritis but not rheumatoid arthritis. These findings suggest that topical capsaicin is a safe and potentially useful drug for the treatment of painful osteoarthritis of the hands.

In a similar study using a weaker concentration of capsaicin cream, 70 patients with osteoarthritis and 31 patients with rheumatoid arthritis of the knees were evaluated. After two weeks of treatment, 80% of the patients using capsaicin reported a pain reduction. Almost half of the patients felt temporary burning after applying capsaicin. These results suggest that capsaicin is a safe and often effective treatment for painful arthritis of the knee in general.

Psoriasis:
In a study of the effects of capsaicin cream on moderate to severe psoriasis, 44 patients with moderate to severe psoriasis applied active capsaicin cream to one half of their body and a placebo cream to the other half. After six weeks, the side of the body on which capsaicin was applied showed improvement (less redness and scaling) compared to the placebo side. Nearly half of the patients reported the onset of burning, stinging, and redness when they started using capsaicin, but these side effects lessened as they continued to use the cream. These results suggest that capsaicin may be a useful therapy for psoriasis.

• Oral ingestion of capsaicin is not recommended.

An active component derived from the fruit of capsicum (Cayenne pepper). This substance has been used to relieve pain, improve circulation and to treat psoriasis topically. External preparations are thought to reduce pain sensation by depleting neurotransmitter, substance P. In clinical trials, capsaicin cream reduces post-surgical pain in cancer patients ⁽¹⁾, however it is not effective for HIV-associated distal symmetrical peripheral neuropathy ⁽²⁾. Studies on capsaicin for arthritis yielded mix results ^{(3) (4)}. Other studies suggest capsaicin is effective against psoriasis ⁽⁵⁾, prurigo nodularis ⁽⁶⁾ and pruritis ani ⁽¹⁵⁾. Intravesical capsaicin injection can induce diuresis ⁽⁷⁾. Intranasal application of capsaicin may be effective in reducing the occurrence of cluster headaches ⁽⁸⁾ and rhinitis ⁽¹⁶⁾. Because of its pungent nature, capsaicin is thought to have carcinogenic activities, however, a study in rats demonstrated that topical application of capsaicin does not induce tumors ⁽¹⁰⁾. Data from another in vitro study suggest that capsaicin can inhibit growth of prostate cancer cells ⁽¹⁷⁾. Common adverse events include skin redness and burning after application but subside following repeated administration ⁽⁹⁾.

• Circulatory disorders
• Colic
• Diabetic neuropathy
• Diarrhea
• Headaches
• Herpes zoster neuropathy
• High cholesterol
• Motion sickness
• Muscle pain
• Osteoarthritis
• Pruritus
• Rheumatoid arthritis
• Spasms
• Stomach and intestinal gas
• Toothache

1. Ellison N, et al. Phase III placebo-controlled trial of capsaicin cream in the management of surgical neuropathic pain in cancer patients. J Clin Oncol 1997;15:2974-80.
2. Paice JA, et al. Topical capsaicin in the management of HIV-associated peripheral neuropathy. J Pain Symptom Manage 2000;19:45-52
3. McCarthy GM, et al. Effect of topical capsaicin in the therapy of painful osteoarthritis of the hands. J Rheumatol 1992;19:604-7.
4. Deal CL, et al. Treatment of arthritis with topical capsaicin: a double-blind trial. Clin Ther 1991;13:383-95.
5. Biesbroeck R, Bril V, Hollander P, Kabadi U, Schwartz S, Singh SP et al. A double-blind comparison of topical capsaicin and oral amitriptyline in painful diabetic neuropathy. Adv.Ther. 1995;12:111-20.
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7. Dasgupta P, et al. Chilies: from antiquity to urology. Br J Urol 1997;80:845-52.
8. Fusco BM, Marabini S, Maggi CA, Fiore G, Geppetti P. Preventative effect of repeated nasal applications of capsaicin in cluster headache. Pain 1994;59:321-5.
9. Newall CA, et al. Herbal Medicines: A Guide for Health Care Professionals. London: Pharmaceutical Press; 1996.
10. Park KK, Chun KS, Yook JI, Surh YJ. Lack of tumor promoting activity of capsaicin, a principal pungent ingredient of red pepper, in mouse skin carcinogenesis. Anticancer Research 1998;18:4201-5.
11. Lynn B. Capsaicin: actions on nociceptive C-fibres and therapeutic potential. Pain 1990;41:61-9.
12. Marsh SJ, Stansfeld CE, Brown DA, Davey R, McCarthy D. The mechanism of action of capsaicin on sensory C-type neurons and their axons in vitro. Neuroscience 1987;23:275-89.
13. Nolano M, Simone DA, Wendelschafer-Crabb G, Johnson T, Hazen E, Kennedy WR. Topical capsaicin in humans: parallel loss of epidermal nerve fibers and pain sensation. Pain 1999;81:135-45.
14. Brinker F. Herb Contraindications and Drug Interactions, 2^nd ed. Sandy (OR): Eclectic Med Publications; 1998.
15. Lysy J, Sistiery-Ittah M, Israelit Y, Shmueli A, Strauss-Liviatan N, Mindrul V, Keret D, Goldin E. Topical capsaicin--a novel and effective treatment for idiopathic intractable pruritus ani: a randomised, placebo controlled, crossover study. Gut. 2003 Sep;52(9):1323-6.
16. Van Rijswijk JB, Boeke EL, Keizer JM, Mulder PG, Blom HM, Fokkens WJ. Intranasal capsaicin reduces nasal hyperreactivity in idiopathic rhinitis: a double-blind randomized application regimen study. Allergy. 2003 58(8):754-61.
17. Mori A, et al. Capsaicin, a component of red peppers, inhibts the growth of androgen-independent, p-53 mutant prostate cancer cells. Cancer Res 2006 66(6):3222-29.