What is the most accurate drug test? & how long do substances like pain killers & cocaine stay in the body with each different test (blood, urine, hair follicle etc.?

Visit this site for information: https://americanaddictioncenters.org/how-long-drugs-system There are many factors that affect the results, including, type of drug, obesity, chronicity of use, method used for the test, cut off level used for a positive result. It is not feasible to address it in detail in this forum.

It is different with each drug so a precise time period cannot be stated. All lab drug tests are accurate.