It depends on the drug used and the amount of drug used. The outer limit of detection for the commonly abused drugs is anywhere from two days for some barbiturates, to over a month for heavy, chronic marijuana use. The soonest that drugs can be detected also depends on the specific drug. Amphetamines and cocaine, for example, may be detected less than an hour after ingestion. The retention times below are only general guidelines. Physical condition, fluid intake, and method and frequency of drug ingestion all influence the time drugs stay in the body.
| Drug Name | Drug Retention Times |
|---|---|
| Amphetamines | 1 – 3 days |
| Barbiturates | 1 day to three weeks |
| Benzodiazepines | 1 – 14 days |
| Cocaine | 2 – 4 days |
| Opiates | 2 days |
| Marijuana Moderate (4 x week) | 5 days or more |
| Marijuana Heavy, Chronic smoker | 20 days or more |