The following is for informational purposes only. I neither endorse nor encourage illegal activities, and this thread is not intended to help anyone negate their way around a drugs test. The word “detectable” is not used to imply that the purpose of this guide is to pass a drugs test; I believe that anyone who is considering taking a drug should know how long it will stick around in their system. However, figures for the complete absence of a drug are difficult to quantify, and so SAMHSA guidelines on a positive result are used instead.
Figures are approximate; as factors such as the metabolism, body mass, age, overall health, drug tolerance, urine pH, level of exercise and fluid intake of the person being tested, the amount and frequency used, the method of administration etc. will all have a bearing.
Substance: duration detecable(urine); duration detectable (hair)
Amphetamines: 1-4 days; 90 days(*)
Anabolic Steroids: 2-3 weeks (oral) 1-3 months (injected) 8 months+ (Naldrolene);
Barbiturates: 1-21 days;
—> short acting (allobarbital, alphenal, amobarbital, aprobarbital, butabarbital, butalbital, butethal, pentobarbital secobarbital) 1-4 days;
—> long-acting (i.g. barbital, phenobarbital) 2-3 weeks;
Benzodiazepines: 1- 42 days;
Buprenorphine (suboxone): 1-3 days; 90 days
Cocaine: 4-5 days; 90 days
Codeine: 2-4 days; 90 days
GHB: 12-24 hrs; undetectable ?
Heroin: 2-4 days; 90 days
Ketamine: 2-4 days; ?
—> norketamine: 14 days; ?
LSD: 12-14 hrs; undetectable
Marijuana: 2-3 (single use) / up to 30 days (chronic use); 60-90 days
MDMA: 3-5 days; 90 days
Meperidine: 4-24 hrs; 90 days
Mephedrone: 1-7 days; ?
Mescalin: 1-4 days; ?
Methadone: 3 days; 97 days
Methamphetamine: 3-5 days; 90 days
Methaqualone: 14 days; 90 days
Morphine: 2-4 days; 90 days
Opium: 1-2 days; 90 days
Oxycodone: 2-4 days;
PCP: 3-7 days; 90 days
Propoxyphene: 6 hrs-2 days; ?
Psilocybin: 1-3 days; ?
Salvia: <12hrs (**)
(*) 90 days accounts for 1.5 inches of most recent growth, the standard sample tested
(**)Probably. Based on a study of the half life of Salvinorin A in rhesus monkeys.
de la Torre, R. et al.  Pharmacology of MDMA in humans; N Y Acad Sci, 2000; 914:225-37
Zhao, H et al.  Profiles of urine samples taken from Ecstasy users at Rave parties: analysis by immunoassays, HPLC, and GC-MS; J Anal Toxicol 2001 May-Jun;25(4):258-69
Jansen, Karl  Ketamine: Dreams and Realities; Multidisciplinary Association for Psychedelic Studies (MAPS)
Schmidt, M.D. et al.  Pharmacokinetics of the plant-derived kappa-opioid hallucinogen salvinorin A in nonhuman primates; Synapse. 2005 Dec 1;58(3):208-10