Items tested for in a standard drug test:
Cannabinoids (marijuana, hash)
Cocaine (cocaine, crack, benzoylecognine)
Amphetamines (amphetamines, methamphetamines, speed)
Opiates (heroin, opium, codeine, morphine)
Phencyclidine (PCP)
To simplify - if clen showed up on drug tests, no one with asthma would have a job.