Improved procedures for in vitro skin irritation testing of sticky and greasy natural botanicals

► Normal washing procedures can lead to an incomplete removal of botanical ingredients. ► We propose an improvement of the washing procedure for in vitro skin irritation test. ► We test 3 new washing procedures for the ability to remove completely sticky/greasy substances. ► The SDS 0.1% PBS solution is the most suitable adaptation to ensure an efficient removal. ► The SDS 0.1% washing leads to an increase in the predictive ability of the assay.