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Topical analgesic (TRPV1 agonist) Pregnancy: Cream considered safe (minimal absorption); Qutenza avoid — limited data.

Capsaicin

Brand names: Zacin (0.025%), Axsain (0.075%), Qutenza (8% patch)

Adult dose

Dose: Osteoarthritis (Zacin 0.025%): apply pea-sized amount QDS for ≥4 weeks. Post-herpetic neuralgia / diabetic neuropathy (Axsain 0.075%): apply QDS. Neuropathic pain (Qutenza 8% patch): single 30-min application (foot) or 60-min application (other sites) by trained clinician; can repeat every 90 days.
Route: Topical
Frequency: Four times daily (cream) or every 90 days (patch)
Wash hands thoroughly after application — avoid eyes, mucous membranes, broken skin. Wear gloves for Qutenza application.

Clinical pearls

  • Mechanism: TRPV1 receptor agonist on C-fibres → initial activation (burning) → defunctionalisation/depletion of substance P → analgesia after 1–2 weeks of regular use.
  • Adherence is the main barrier — burning is intense initially. Counsel patient that effect needs ~2 weeks of regular QDS use; missed doses reset desensitisation.
  • Useful add-on in OA hand or knee unresponsive to topical NSAIDs (NICE NG226 OA Guideline 2022).
  • Qutenza 8% patch: pretreat with topical lidocaine 4% for 60 min before patch application; monitor BP during and 1 hr after — avoid in uncontrolled HTN.
  • Cream for osteoarthritis is OTC; Qutenza patch specialist pain clinic only.
  • AVOID applying with hot water, heating pads, or after exercise — markedly intensifies burning.

Contraindications

  • Hypersensitivity to capsaicin or chilli peppers
  • Application to broken or inflamed skin
  • Use near eyes or mucous membranes
  • Children <18 (Qutenza)

Side effects

  • Burning, stinging on application (very common — 'desensitises' over 1–2 weeks; worst initially)
  • Erythema at application site
  • Cough, sneezing if vapours inhaled
  • Transient ↑ BP, tachycardia (Qutenza application — pretreat with topical lidocaine)
  • First-degree burns (if applied to broken skin or under occlusive dressing)

Interactions

  • Topical NSAIDs / heat: additive irritation

Monitoring

  • Pain score (e.g., NRS) at 4 weeks
  • BP during Qutenza application

Reference: BNF 90; SmPC Zacin / Axsain / Qutenza; NICE NG226 (Osteoarthritis 2022); NICE CG173 (Neuropathic Pain 2013); BPS Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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