Can capsaicin be used to treat chronic low‑back pain in adults when NSAIDs and physical therapy are insufficient, and what is the recommended dosing and precautions?

Capsaicin for Chronic Low Back Pain

Capsaicin is not recommended as a treatment for chronic low back pain when NSAIDs and physical therapy are insufficient, as the evidence for its efficacy in this condition is limited and it is specifically recommended only for neuropathic pain conditions, not mechanical or axial low back pain. 1

Evidence-Based Rationale

Why Capsaicin Is Not Appropriate for Low Back Pain

• The 2022 CDC guidelines explicitly state that capsaicin patches are recommended for neuropathic pain (diabetic neuropathy and postherpetic neuralgia), not for chronic low back pain 1

• The same guidelines acknowledge that "evidence on topical lidocaine and capsaicin is limited" even for neuropathic conditions 1

• The 2017 American College of Physicians systematic review on low back pain treatments evaluated topical capsaicin and lidocaine but found insufficient evidence to include them in treatment recommendations for low back pain 1

• Research evidence shows capsaicin's efficacy is primarily in neuropathic conditions (postherpetic neuralgia, HIV-neuropathy, diabetic neuropathy), not mechanical back pain 2, 3, 4

What Should Be Used Instead

For chronic low back pain inadequately controlled by NSAIDs and physical therapy, duloxetine is the evidence-based next step, with a modest but meaningful effect on pain reduction. 1

Recommended Treatment Algorithm:

1. First-line pharmacologic option: Continue NSAIDs at the lowest effective dose for shortest duration, as they reduce chronic low back pain by approximately 12.4 points on a 0-100 scale 1, 5

2. Add duloxetine 30mg daily: Start with 30mg for one week, then increase to 60mg daily if tolerated 1, 6

   • Duloxetine has moderate-quality evidence for small improvements in chronic low back pain 1
   • It is FDA-approved for chronic musculoskeletal pain and particularly effective in older adults 6

3. Consider tramadol as third-line: If duloxetine is ineffective or not tolerated, tramadol can be used cautiously 6

4. Intensify nonpharmacologic approaches: The American College of Physicians strongly recommends continuing or adding exercise therapy, spinal manipulation, massage, or cognitive behavioral therapy alongside medication 6

Important Caveats About Capsaicin

• High-concentration (8%) capsaicin patches require application under controlled conditions, often with local anesthetic, due to intense initial burning 2

• Even in neuropathic pain conditions where it is indicated, capsaicin provides benefit to only about 10% more patients than placebo, with NNT values of 6-12 2, 4

• Local skin reactions occur in approximately one-third of patients and are often poorly tolerated 3, 4

• The effect is described as "moderate to poor efficacy" even for its approved indications 4

Common Pitfall to Avoid

Do not assume that because capsaicin is "topical" and "natural" it is appropriate for all types of chronic pain. The mechanism of action (desensitization of cutaneous nociceptors) is specifically suited to neuropathic pain with cutaneous hypersensitivity, not the deep somatic pain of mechanical low back pain 7, 2. Using capsaicin for low back pain would expose patients to significant local adverse effects without evidence of benefit, delaying appropriate treatment with duloxetine or other evidence-based therapies 1.