Capsaicin applied to the skin for chronic neuropathic pain in adults

Derry S, Lloyd R, Moore RA, McQuay HJ

Published Online:

October 7, 2009

Topical (rubbed on the skin) capsaicin may provide some pain relief in various neuropathic pain conditions, but at the expense of local skin irritation such as burning and stinging. The amount of pain relief experienced remains uncertain because of different definitions used in these studies, and confidence in our estimates of the number of individuals likely to benefit is not strong because of the small numbers of participants in the studies and probable differences in response for different neuropathic conditions. Capsaicin, either alone or in combination with other treatment, may provide useful pain relief in individuals who fail to respond to, or cannot tolerate, other available therapies.

Abstract (click to read)

Background:

Topical creams with capsaicin are used to treat pain from a wide range of chronic conditions including neuropathic pain. Following application to the skin capsaicin causes enhanced sensitivity to noxious stimuli, followed by a period with reduced sensitivity and, after repeated applications, persistent desensitisation. There is uncertainty about the efficacy and tolerability of capsaicin for treating painful chronic neuropathies.

Objectives:

To review the evidence from controlled trials on the efficacy and tolerability of topically applied capsaicin in chronic neuropathic pain in adults.

Search strategy:

Cochrane CENTRAL, MEDLINE, EMBASE and Oxford Pain Relief Database, searched in May 2009.

Selection criteria:

Randomised, double blind, placebo controlled studies of at least six weeks' duration, using topical capsaicin to treat neuropathic pain.

Data collection and analysis:

Two review authors independently assessed trial quality and validity, and extracted data. Information was extracted on numbers of participants with pain relief (clinical improvement) after at least six weeks, and with local skin reactions, and used to calculate relative risk and numbers needed to treat to benefit (NNT) and harm (NNH). Details of definition of pain relief and specific adverse events were sought.

Main results:

Six studies (389 participants in total) compared regular application of low dose (0.075%) capsaicin cream with placebo cream; the NNT for any pain relief over six to eight weeks was 6.6 (4.1 to 17). Two studies (709 participants in total) compared a single application of high dose (8%) capsaicin patch with placebo patch; the NNT for ≥ 30% pain relief over twelve weeks was 12 (6.4 to 70). Local skin reactions were more common with capsaicin, usually tolerable, and attenuated with time; the NNH for repeated low dose application was 2.5 (2.1 to 3.1). There were insufficient data to analyse either data set by condition or outcome definition. All studies satisfied minimum criteria for quality and validity, but maintenance of blinding remains a potential problem.

Authors' conclusions:

Capsaicin, either as repeated application of a low dose (0.075%) cream, or a single application of a high dose (8%) patch may provide a degree of pain relief to some patients with painful neuropathic conditions. Local skin irritation, which is often mild and transient but may lead to withdrawal, is common. Systemic adverse effects are rare. Estimates of benefit and harm are not robust due to limited amounts of data for different neuropathic conditions and inconsistent outcome definition.

This record should be cited as:

Derry S, Lloyd R, Moore RA, McQuay HJ. Topical capsaicin for chronic neuropathic pain in adults. Cochrane Database of Systematic Reviews 2009, Issue 4. Art. No.: CD007393. DOI: 10.1002/14651858.CD007393.pub2

Assessed as up to date:

May 5, 2009

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Primary Review Group:

Pain, Palliative and Supportive Care Group

PEARLS - Practical Evidence About Real Life Situations (click to read)

Clinical question:

How effective is topical capsaicin for chronic neuropathic pain in adults?

Bottom line:

Six studies compared regular application of low-dose (0.075%) capsaicin cream with placebo cream; the NNT* for any pain relief over 6 to 8 weeks was 6.6 (4.1 to 17). Two studies compared a single application of high-dose (8%) capsaicin patch with placebo patch; the NNT for ≥30% pain relief over 12 weeks was 12 (6.4 to 70). Local skin irritation, which is often mild and transient but may lead to withdrawal, is common. The NNH** for repeated low-dose application was 2.5 (2.1 to 3.1). Systemic adverse effects were rare. * NNT = number needed to treat to benefit 1 individual (95% confidence intervals) ** NNH = number needed to treat to cause harm in 1 individual (95% confidence intervals)

Caveat:

All studies satisfied minimum criteria for quality and validity but maintenance of blinding remained a potential problem. The limited amount of data for different neuropathic conditions and inconsistent definition of outcome meant estimates for the number of participants achieving clinically useful levels of pain relief were not robust.

Context:

Topical creams with capsaicin are used to treat pain resulting from a wide range of chronic conditions, including neuropathic pain. Following application to the skin, capsaicin causes enhanced sensitivity to noxious stimuli, followed by a period with reduced sensitivity and, after repeated applications, persistent desensitisation.

Cochrane Systematic Review:

Derry S et al. Topical capsaicin for chronic neuropathic pain in adults. Cochrane Reviews 2009, Issue 4. Article No. CD007393. DOI: 10.1002/14651858.CD007393.pub2. This review contains 8 trials involving 1098 participants.

Authored by:

Brian R McAvoy

Cochrane Primary Health Care Field

Health topics:

Anaesthesia & pain control > Chronic non-cancer pain management > Pharmacological therapies

Complementary & alternative medicine > Anaesthesia & pain control > Chronic non-cancer pain management

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

Capsaicin applied to the skin for chronic neuropathic pain in adults

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