Analysis of hair is a type of drug screening which has been carried out for many years.  Countries and courts around the world use it as the results are legally admissible and are considered to be very accurate.  Many of the world’s most commonly used drugs can be detected in this way, including cocaine and marijuana.

In addition, both the US and the UK use hair testing for alcohol markers.  Guidelines have been published by the Society of Hair Testing for both drug and alcohol markers.