Further research efforts by Yasunori Takayama, of Okazaki Institute for Integrative Bioscience in Japan, and colleagues have highlighted that capsaicin-evoked events (either pain sensation or pain relief) involve not only capsaicin receptor TRPV1 but also calcium-activated chloride channel ANO1. 

“TRPV1 antagonists as pain killers are not in the market because of their small pain-reducing effects and serious side effects, such as body temperature elevation.  Therefore, blocking ANO1 function or TRPV1/ANO1 interaction would be a promising way to develop a novel type of pain killers,” said Takayama.2


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Other research efforts have shown that capsaicin causes heat hyperalgesia and cold hyposensitivity, increased paradoxical heat sensations, and changed thermal grill illusion. 

In one study, Nanna Finnerup, MD, of Aarhus University Hospital in Denmark, and colleagues aimed to understand cold and warm integration and understand the mechanisms of the thermal grill illusion. “We used capsaicin as a model to increase the heat pain sensation and decrease the cold sensation to understand basic pain and thermal physiology,” said Finnerup. 

The researchers found that those with paradoxical heat sensations after capsaicin use had higher detection thresholds to both cold and hot than those without paradoxical heat sensations, but there was no difference in thermal pain threshold.3

Availability and Safety of Capsaicin

Capsaicin creams and patches are available as over-the-counter medications in most U.S. pharmacies, but Rohacs believes these agents provide limited efficacy.  “These OTC preparations most likely never reach the nerve endings at high enough concentrations to actually desensitize the nerve,” said Rohacs. Yet local preparations with higher concentrations as patches as well as injectable formulas have been tested in clinical trials.