Although hair is considered the best matrix to detect retrospective drug abuse, urine can also be used for this purpose.
It is particularly useful if urine testing is used in combination with hair analysis to provide an enhanced time-line for drug detection. The detection of drugs in urine is only possible for several days after the last instance of use (except cannabis). This recent coverage of drug abuse complements the ability of hair testing to detect drug abuse over a retrospective period of months
Although urine testing alone has a much shorter detection window than hair, a series of short-notice urine tests can provide some evidence of abstention.
Because alcohol is only detectable in urine for less than 12 hours, urine alcohol testing has limited value. The analysis of hair for alcohol metabolites is a much more satisfactory means of testing for chronic alcohol abuse.