Authors: Hunter Groninger MD and Randall E Schisler MD
Background Derived from Capsicum chili peppers, capsaicin has been used as a topical analgesic for centuries. Available in both over-the-counter and prescription strengths, capsaicin preparations have been studied and utilized for management of neuropathic pain. This Fast Fact reviews use of capsaicin for topical neuropathic analgesia, including the new 8% single-dose capsaicin patch (‘Qutenza’).
Mechanism of Action Capsaicin is a highly selective agonist for TRPV1 receptors expressed in afferent neuronal C fibers and some Aδ fibers. Local activation of TRPV1 receptors by heat, pH changes, or endogenous lipids normally leads to nerve depolarization propagated to spinal cord and brain, causing local heat, stinging, and/or itching sensations. Through intracellular enzymatic, cytoskeletal, and osmotic changes, prolonged activation of TRPV1 by capsaicin results in loss of receptor functionality, causing impaired local nociception for extended periods. At higher concentrations, topical capsaicin appears to promote temporary neurolysis, with re-innervation occurring weeks after cessation of drug therapy (1,2). Capsaicin-induced local depletion of substance P was previously thought to be its mechanism for pain relief. However, this is no longer considered to be the case (1).
Indications Topical capsaicin has shown analgesic benefits in post-herpetic neuralgia, painful polyneuropathies including diabetic and HIV-related neuropathy, and postmastectomy/surgical neuropathic syndromes (3). The capsaicin 8% patch is FDA-approved for post-herpetic neuralgia. Its efficacy in other neuropathies is still being investigated. Generally, these painful areas should involve a discrete area of the body such as a distal extremity or surgical scar. There is no well-defined limit to the body surface area which can be treated with capsaicin cream. The 14 x 20cm capsaicin 8% patch is approved for application of up to 4 patches at a time. Capsaicin creams have been used in children; there are no data about use of the 8% patch.
Clinical Use Capsaicin is commercially available as 0.025%, 0.075%, and 0.1% creams. Creams are applied by patients or caregivers 3-4 times per day. The duration of treatment with the cream is empiric. A single-application high-dose capsaicin 8% patch is available. The patch is placed on the skin for 60 minutes by a medical professional in a clinic, then removed. Because the patch application itself is painful, the area is pretreated with lidocaine cream, and residual capsaicin is cleaned afterwards with a special cleansing product. Up to 4 patches may be applied at one time, and repeated as often as every 3 months (4).
Effectiveness In a recent systematic review, capsaicin 0.075% cream demonstrated statistically significant benefit in post-herpetic neuralgia, post-surgical neuropathies, and diabetic neuropathy, compared to placebo (3). The analgesic effect of capsaicin 0.075% cream has been demonstrated throughout 4-12 weeks of study follow-up, although it may take weeks of application to achieve significant benefit. Although studies demonstrate its effectiveness in musculoskeletal pain, capsaicin 0.025% cream has not been adequately studied for neuropathic pain. The efficacy of the single high-dose capsaicin 8% patch has been observed up to 12 weeks in published data (5). It is effective for post-herpetic neuralgia, however there have been mixed results with the patch for HIV-related neuropathy. To date, no head-to-head trials have compared the capsaicin 8% patch to capsaicin 0.075% cream.
Toxicity and Precautions Capsaicin should not be used on open wounds. Major side effects are localized and include erythema and uncomfortable burning, stinging, or itching. Over repeated applications, these burning/stinging sensations decrease, corresponding with progressive neuronal defunctionalization. Inhalation of capsaicin can cause nasopharyngeal or respiratory irritation, sneezing, and tearing. Patients are advised to use gloves while applying the cream, avoid contact with eyes and mucous membranes, and wash hands after application. Transient hypertension associated with increased local pain has been noted. Cessation of capsaicin use due to side effects appears more common with repeated low dose cream application (15% of patients) compared to the patch (1% of patients in a clinical trial setting) (5).
Cost Capsaicin 0.025%, 0.075%, 0.1% creams are available over-the-counter (approximately $8/oz). One capsaicin 8% patch costs approximately $800 (plus clinician fees for application). Costs for 3-month supplies of relevant neuropathic pain medications are: ~$700 for lidocaine 5% patches, 1 a day; ~$900 for pregabalin 100 mg 3 times a day; ~$300 for gabapentin 600 mg 3 times a day; ~$50 for amitriptyline 100 mg once daily (6).
Anand P, Bley K. Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high concentration capsaicin 8% patch. Br J Anaesthesia. 2011; 107(4):490–502.
Jones VM, Moore KA, Peterson DM. Capsaicin 8% topical patch: a review of the evidence. J Pain Palliat Pharmacotherapy. 2011; 25:32-41.
Jorge LL, Feres CC, Teles VEP. Topical preparations for pain relief: efficacy and patient adherence. J Pain Research. 2011; 4:11-24.
Detailed instructions for patch application are available in the official Prescribing Information document. Available at http://www.qutenza.com/_docs/qutenza_full_PI_.pdf. Accessed February 16, 2012.
Derry S, Lloyd R, Moore RA, McQuay HJ. Topical capsaicin for chronic neuropathic pain in adults. Cochrane Database Syst Rev . 2009; 4:CD007393.
Prices from: Drugstore.com Online Pharmacy. Available at: http://drugstore.com. Accessed: 27 Sept. 2011.
Authors’ Affiliations: Clinical Center, National Institutes of Health, Bethesda, MD (HG); Carolinas Medical Center/Northeast, Concord, NC (RES).
Conflicts of Interest Statement: The authors have disclosed no relevant conflicts of interest.
Fast Facts and Concepts are edited by Drew A Rosielle MD, Palliative Care Program, University of Minnesota Medical School and Fairview Health Services, and are published by the End of Life/Palliative Education Resource Center at the Medical College of Wisconsin. For more information write to: firstname.lastname@example.org. More information, as well as the complete set of Fast Facts, are available at EPERC: http://www.mcw.edu/eperc.
Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Groninger H, Schisler RE. Capsaicin for neuropathic pain. Fast Facts and Concepts. July 2012; 255. Available at: http://www.eperc.mcw.edu/EPERC/FastFactsIndex/ff_255.htm.
Disclaimer: Fast Facts and Concepts provide educational information. This information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Facts cite the use of a product in a dosage, for an indication, or in a manner other than that recommended in the product labeling. Accordingly, the official prescribing information should be consulted before any such product is used.