Toxicological hair analysis makes it possible to assess whether a patient has recently taken drugs, for example, but also whether he has abused any medicines (e.g. opioid painkillers). But what does such a test consist of - with what exact techniques is it possible to detect the above-mentioned and also other substances in the hair? What about people who do not have hair on their head - is a toxicological hair analysis impossible for them or can it still be performed?