Drug Test Overview

Drug tests are common in many workplaces as employers seek to determine whether a new potential employee or an existing employee is using or abusing illicit drugs. Drug testing by parents has grown in popularity since the advent of home drug testing kits and the relative affordability of such test kits in recent years.

The most common questions posted to forum discussion boards typically revolve around users wondering "how long do drugs stay in your system?" or something specific such as "how long will marijuana stay in my system?". Typically these questions are posed by drug users who have no intention of quitting and simply want to beat a drug test for the purpose of gaining employment, not getting in trouble with their probation or parole officer, or avoiding detection by their parents. First, the real answer is getting permanent help for alcohol or drug addiction. Second, the answer is simply that it nearly always varies based on a number of factors such as your height, weight, body fat, level of physical activity, and other factors such as dosage, potency, and consistency of use.

The majority of drug tests are urine tests. There are two types.

standard urine tests	cannabinoids (cannabis, marijuana, hash) A marijuana drug test specifically looks for the level of THC (Tetrahydrocannabinol) in your body. amphetamines (amphetamines, methamphetamine) cocaine (cocaine hydrochloride, crack) opiates (heroin, opium, morphine, codeine) PCP (pencyclidene)
advanced urine tests	barbituates (phenobarbital) qualuudes (methaqualone) benzodiazepines (valium, rohypnol) methadone ethanol (alcohol)
hair tests	can detect most drugs up to 90 days after use.
blood tests	are rare and expensive, and usually only done in criminal investigations
also	mouth swabs and saliva samples can be analyzed for drug use but these are less effective

Parents and employers conducting non-clinical drug testing should be aware that users frequently consume products that aid in rendering a marijuana drug test (ext. link) innacurate.

The internet has spurred a large increase in sites offering kits, tonics, and recipes to aid users who seek to pass a drug test (ext. link), though the effectiveness of such methods varies.
Reference: The ACLU on Workplace Drug Testing (ext. link)

LOOK UP CHART

substance	standard tests	detection period (hrs)	comments
amphetamines	Y	24-72	false positives may be caused by a variety of over-the-shelf & prescription medicines - see full list here
cannabis	Y	48-72	can be detected up to 12 weeks in a chronic user
cocaine	Y	48-72
ecstasy (MDMA) Ecstasy Drug Testing	N	24-72	can be detected by a test for Amphetamines
heroin (opiates)	Y	24-48	several over the counter medicines may cause false positives in heroin drug tests - list here
ketamine Ketamine Tests	N	unknown	tests for K are extremely unlikely
LSD More on LSD drug testing here	N	24-48	very unlikely test as amounts used are microscopic
mushrooms (psilocybin) Magic Mushrooms Drug Test	N	unknown	very unlikely test
methamphetamines	Y	24-96