Skip navigation
Acute Pain | Chronic Pain | General

Topical capsaicin for pain relief

Clinical bottom line:

Topically applied capsaicin is useful in alleviating the pain associated with diabetic neuropathy, osteoarthritis and psoriasis. The numbers-needed-to-treat for some improvement are 4.2 (2.9 to 7.5), 3.3 (2.6 to 4.8) and 3.9 (2.7 to 7.4) respectively. These may not be the most effective treatments; for example, oral anticonvulsants are more effective in diabetic neuropathy.

It remains to be established whether capsaicin is beneficial in postherpetic neuralgia and post-mastectomy pain. Current evidence, based on very small numbers, suggests no benefit.


Capsaicin is an alkaloid derived from chillies. It first entered European knowledge after Columbus' second voyage to the New World in 1494. There is evidence that capsaicin can deplete substance P in local nerve sensory terminals. Substance P is thought to be associated with initiation and transmission of painful stimuli, as well as a number of diseases including arthritis, psoriasis and inflammatory bowel disease.

Systematic review

Zhang WY, Li, Wan Po A. The effectiveness of topically applied capsaicin. A meta-analysis. Eur J Clin Pharmacol. 1994; 46: 517-22.

Inclusion criteria were randomised, double-blind, placebo controlled trials of topical capsaicin for pain relief; data extractable to show proportion of patients showing improvement.

Reviewers calculated odds ratios. We have calculated relative benefits and numbers-needed-to-treat (with 95% confidence intervals) for some benefit with capsaicin.

Reviewers noted that blinding may not be complete owing to the irritant effects of capsaicin when applied to the skin.

Findings

Diabetic neuropathy

Four trials (144 capsaicin patients, 165 controls) looked at capsaicin 0.075% cream, four times daily for 4 to 8 weeks. Two of four trials showed significant benefit with capsaicin. When data were pooled for diabetic neuropathy, capsaicin had a number-needed-to-treat of 4.2 (2.9 to 7.5). For comparison, oral anticonvulsant therapy for diabetic neuropathy in 66 treated patients in two trials had a number-needed-to-treat of 2.5 (1.8 to 4.0).

Osteoarthritis

Three trials (192 capsaicin patients, 190 controls) looked at capsaicin. Two trials reported on 0.025% and one on 0.075%, four times daily for four weeks. The endpoint was articular tenderness or physicians' global assessment of pain relief.

One of three trials showed significant benefit for capsaicin. When the data were pooled for osteoarthritis, capsaicin had a number-needed-to-treat of 2.9 (2.0 to 4.1).

Postherpetic neuralgia

One trial (16 capsaicin patients, 16 controls) looked at capsaicin 0.075% three or four times daily for six weeks. Although this trial reported a significant improvement with capsaicin, the relative benefit of 14 (0.5 to 3.2) suggested no significant benefit with capsaicin.

Post-mastectomy pain

One trial (13 capsaicin patients, 10 controls) looked at capsaicin 0.075% daily for six weeks. Although this trial reported a significant improvement with capsaicin, the relative benefit of 3.9 (0.5 to 28) suggested no significant benefit with capsaicin.

Psoriasis

Four trials (115 capsaicin patients, 130 controls) looked at capsaicin 0.025% four times daily for six to eight weeks. The endpoint was much better or better rating of overall appearance. Four of four trials reported improvement on at least one measure. For psoriasis, capsaicin had a number-needed-to-treat of 3.9 (2.7 to 7.4).

Figure: Efficacy of topical capsaicin for chronic pain in various conditions compared with placebo

Table 1: Relative benefit and NNT for topical capsaicin in various conditions

Condition
Number of trials

Capsaicin at least 50% pain relief Number/Total

Placebo at least 50% pain relief Number/Total

Relative benefit (95%CI)

NNT (95%CI)

diabetic neuropathy
4

105/144

81/165

1.5 (1.2 to 1.8)

4.2 (2.9 to 7.5)

osteoarthritis
3

87/192

30/190

2.9 (2.0 to 4.1)

3.3 (2.6 to 4.8)

postherpetic neuralgia
1

4/16

1/16

14 (0.5 to 32)

NC

postmastectomy pain
1

5/13

1/10

3.9 (0.5 to 28)

NC

psoriasis
4

78/115

55/130

1.6 (1.3 to 2.0)

3.9 (2.7 to 7.4)

NC - NNT not calculated (no significant relative benefit)

Adverse effects

Reviewers did not include this data, but noted that capsaicin has an irritant effect that may wear off with repeated use.

Further References

The current review is developed in McQuay HJ, Moore RA. Chapter 33, Topical Capsaicin. An evidence-based resource for pain relief. Oxford. Oxford University Press, 1998

Related topics