Characteristics of substances on screening immunoassays
| Substance | How it appears on standard urine toxicology screening | How long it remains detectable after usea | Sources of false positivityb |
|---|---|---|---|
| Amphetamine | Amphetamine | 2-3 days (occasional use) 1 week (very heavy use) | Bupropion Ephedrine Vicks Vapor Inhalerc |
| Barbiturate | Barbiturate | Short-acting: 1-3 days Long acting: 2-3 weeks | Ibuprofen Naproxen |
| Benzodiazepine | Benzodiazepine | 2-3 days | Efavirenz Sertraline |
| Buprenorphine | Usually requires separate assay | 1-3 days | Amisulpride (rare) Tramadol |
| Cannabis | Cannabinoid | 3-4 days (occasional use) 7-10 days (regular use) 4+ weeks (heavy use) | Efavirenz |
| Cocaine | Cocaine | 2-3 days (occasional use) 3 weeks (heavy use) | Topical anesthetics containing cocaine |
| Methadone | Methadone | 2-3 days | Quetiapine |
| Codeine Hydrocodone Hydromorphone Morphine | Opiate | 2-3 days | Heroin Levofloxacin Other opiates Ofloxacin Oxycodone |
| Oxycodone | Oxycodone | 2-3 days | Naloxone |
| Phencyclidine (PCP) | Phencyclidine (PCP) | 2-3 days (occasional use) 1 week (very heavy use) | Tramadol Venlafaxine |
↵a Duration of detection varies with dose taken, frequency of use, and individual metabolism.
↵b Gas chromatography-mass spectrometry is needed to distinguish; false-positives vary by specific assay used.
↵c Vicks Vapor inhaler contains levomethamphetamine, which is the L-entaniomer of methamphetamine. Although the L isomer has no addictive potential or central nervous system effects, repeated use may result in a positive urine drug screen.
Compiled from information in references 1–3, 37–49.