Ethnic variations in facial skin neurosensitivity assessed by capsaicin detection thresholds

Ethnic variations in sensitive skin have not been thoroughly explored and remain controversial.

To objectively assess ethnic variations in facial skin neurosensitivity through individual detection thresholds of topically applied capsaicin.

The single-blind, controlled study was performed in 144 women from three ethnicities: Asian, African, and Caucasian. Five solutions with increasing capsaicin concentration were successively applied to one side of nasolabial folds, while the other side simultaneously received the vehicle as control. The test was discontinued when the volunteer reported on the capsaicin side a sensation whatever its nature. Otherwise the experimenter continued the test, using the next solution with higher capsaicin content and so on, until the subject experienced a sensation on the capsaicin side.

Each ethnic group was divided into six sub-groups according to the level of sensitivity to capsaicin, i.e. from detection of the lowest concentration up to no detection of the highest concentration, 100-fold higher. Asian women tended to have higher capsaicin detection thresholds than Caucasians, but lower thresholds than Africans. Nevertheless, the distribution did not greatly differ between the three ethnicities.

The capsaicin skin neurosensitivity test is painless and the changes across individuals of different ethnic backgrounds appear minimal.