If you want to find out drug levels in someone’s system, you have a few different options. You can analyse a sample of their urine, blood, sweat, breath or, of course, hair. Each will give you a picture of when the person used drugs, and the amount.
Not all tests give you the same information. Some tests, such as blood or saliva tests, give a small window of insight into a user’s drug use – hours and days. Others, like hair testing can analyse drug use over a longer period – weeks and months.