Topical acetylsalicylate attenuates capsaicin induced pain, flare and allodynia but not thermal hyperalgesia.

The effect of acetylsalicylic acid (ASA) on capsaicin-evoked activation of cutaneous nociceptors was tested in a double blind study in 10 volunteers. Capsaicin (2% in ethanol) was applied topically for 30 min. Topical ASA (0.25 g/ml) reduced pain intensity and axon reflex flare size. Also, areas of secondary hyperalgesia to light touch and pin-prick were diminished. In contrast, capsaicin-induced heat hyperalgesia was unaffected by ASA. It is concluded that ASA counteracts the excitatory effects of capsaicin on nociceptors and mechanical hyperalgesia but not its sensitizing action to heat.

RCT Entities:   Population Interventions Outcomes