Effects of Shampoo and Water Washing on Hair Cortisol Concentrations
October 2010
in “
Clinica Chimica Acta
”
TLDR Washing hair with water or shampoo lowers cortisol levels in hair.
The study investigated the effects of shampoo and water washing on hair cortisol concentrations using hair samples from 20 rhesus monkeys. It found that repeated washing, whether with shampoo or water alone, significantly reduced hair cortisol levels. This reduction was primarily due to water exposure, as cortisol levels after 20 water-only washes were similar to those after 20 shampoo washes. The findings suggested that repeated exposure to water can leach cortisol from hair, potentially leading to underestimation of chronic hormone deposition in hair cortisol studies. Collecting samples close to the scalp and considering hair washing frequency were recommended for accurate human hair cortisol assessments.
