Active constituents
Cayenne contains a resinous and pungent substance known as capsaicin. Topical application of capsaicin relieves pain and itching by acting on sensory nerves.1 Capsaicin temporarily depletes “substance P”, a chemical in nerves that transmits pain sensations. Without substance P, pain signals can no longer be sent. The effect is temporary. Numerous double-blind trials have proven topically applied capsaicin creams are helpful for a range of conditions, including nerve pain in diabetes (diabetic neuropathy),2 3 post-surgical pain,4 5 6 psoriasis,7 muscle pain due to fibromyalgia,8 nerve pain after shingles (postherpetic neuralgia),9 10 osteoarthritis pain,11 12 and rheumatoid arthritis pain.13
With the aid of a healthcare professional, capsaicin administered via the nose may also be a potentially useful therapy for cluster headaches. This is supported by a double-blind trial.14 Weaker scientific support exists for the use of capsaicin for migraines.15
Injecting capsaicin directly into the urinary bladder has reduced symptoms of one type of bladder dysfunction (neurogenic hyperreflexic bladder)16 that results from spinal cord and other nerve injuries. Capsaicin is not known to help other bladder conditions, such as chronic bladder pain. The placing of cayenne or capsaicin products into the bladder has only been performed in clinical experiments and should only be done by a urologist.
Modest reductions in appetite have been found in healthy Japanese women and white men when they consumed 10 grams of cayenne pepper along with meals in a double-blind trial.17 A similar trial found that cayenne could increase metabolism of dietary fats in Japanese women.18 These trials suggest cayenne may help in the treatment of obesity.
In a double-blind study of people with dyspepsia (heartburn),
supplementation with 833 mg of cayenne powder in capsules, three times per day before meals, reduced heartburn symptoms by 48%, compared with a placebo. However, two of 15 individuals receiving cayenne discontinued it because of abdominal pain.19
References
1. Lynn B. Capsaicin. Actions on nociceptive C-fibers and therapeutic potential. Pain 1990;41:61–9.
2. Capsaicin study group. Treatment of painful diabetic neuropathy with topical capsaicin. A multicenter, double-blind, vehicle-controlled study. The capsaicin study group. Arch Int Med 1991;151:2225–9.
3. Capsaicin study group. Effect of treatment with capsaicin on daily activities of patients with painful diabetic neuropathy. The capsaicin study group. Diabet Care 1992;15:159–65.
4. Ellison N, Loprinzi CL, Kugler J, 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.
5. Watson CPN, Evans RJ, Watt VR. The postmastectomy pain syndrome and the effect of topical capsaicin. Pain 1989;38:177–86.
6. Watson CPN, Evans RJ. The postmastectomy pain syndrome and topical capsaicin: a randomized trial. Pain 1992;51:375–9.
7. Bernstein JE, Parish LC, Rapaport M, et al. Effects of topically applied capsaicin on moderate and severe psoriasis vulgaris. J Am Acad Dermatol 1986;15:504–7.
8. McCarty DJ, Csuka M, McCarthy G, et al. Treatment of pain due to fibromyalgia with topical capsaicin: A pilot study. Semin Arth Rhem 1994;23:41–7.
9. Watson CP, Tyler KL, Bickers DR, et al. A randomized vehicle-controlled trial of topical capsaicin in the treatment of postherpetic neuralgia. Clin Ther 1993;15:510–26.
10. Watson CP, Evans RJ, Watt VR. Postherpetic neuralgia and topical capsaicin. Pain 1988;33:333–40.
11. McCarthy GM, McCarty DJ. Effect of topical capsaicin in the therapy of painful osteoarthritis of the hands. J Rheumatol 1992;19:604–7.
12. Deal CL, Schnitzer TJ, Lipstein E, et al. Treatment of arthritis with topical capsaicin: A double-blind trial. Clin Ther 1991;13:383–95.
13. Deal CL, Schnitzer TJ, Lipstein E, et al. Treatment of arthritis with topical capsaicin: A double-blind trial. Clin Ther 1991;13:383–95.
14. Marks DR, Rapoport A, Padla D, et al. A double-blind placebo-controlled trial of intranasal capsaicin for cluster headache. Cephalalgia 1993;13:114–6.
15. Levy RL. Intranasal capsaicin for acute abortive treatment of migraine without aura. Headache 1995;35:277 [letter].
16. de Seze M, Wiart L, Ferrier JM, et al. Intravesical instillation of capsaicin in urology: A review of the literature. Eur Urol 1999;36:267–77 [review].
17. Yoshioka M, St-Pierre S, Drapeau V, et al. Effects of red pepper on appetite and energy intake. Br J Nutr 1999;82:115–23.
18. Yoshioka M, St-Pierre S, Suzuki M, Tremblay A. Effects of red pepper added to high-fat and high-carbohydrate meals on energy metabolism and substrate utilization in Japanese women. Br J Nutr 1998;80:503–10.
19. Bortolotti M, Coccia G, Grossi G. Red pepper and functional dyspepsia. N Engl J Med 2002;346:947–8 [letter].
20. Siften DW (ed). Physicians’ Desk Reference for Nonprescription Drugs. Montvale, NJ: Medical Economics, 1998, 790–1.
21. Bortolotti M, Coccia G, Grossi G. Red pepper and functional dyspepsia. N Engl J Med 2002;346:947-8 [letter].
22. Siften DW (ed). Physicians’ Desk Reference for Nonprescription Drugs. Montvale, NJ: Medical Economics, 1998, 790–1.
23. Lopez-Carrillo L, Avila M, Dubrow R. Chili pepper consumption and gastric cancer in Mexico: A case-control study. Amer J Epidem 1994;139:263–71.
24. Buiatti E, Palli D, Decarli A, et al. A case-control study of gastric cancer and diet in Italy. Int J Cancer 1989;44:611–6.
25. Surh YJ, Lee SS. Capsaicin in hot chili pepper: Carcinogen, co-carcinogen or anticarcinogen? Food Chem Toxic 1996;34:313–6.