Depending on the drug type and concentration, the length for which the drugs can proliferate the blood stream can significantly vary. It also depends on the drugs detection method to quantize the concentration of a drug in blood.
Other variables which affect the drug retention are individual’s health, dietary habits, physical activity and lifestyle, and the presence of other substances such as supplements, herbs, alcohol and other drugs.
The following is an approximate average estimation of the time length for which the drugs are generally detectable.
| Alcohol | 3-5 days in urine, 10-12 hours in blood |
| Amphetamines | 1-3 days in urine and around 12 hours in blood |
| Barbiturates | 2-4 days in urine and 1-2 days in blood |
| Benzodiazepines | 3-6 weeks in urine and 2-3 days in blood |
| Cannabis | 7-30 days in urine and up to 2 weeks in blood |
| Cocaine | 3-4 days in urine and 1-2 days in blood |
| Codeine | 1 day in urine and up to 12 hours in blood |
| Heroin | 3-4 days in urine and up to 12 hours in blood |
| LSD | 1-3 days in urine and up to 2-3 hours in blood |
| MDMA | 3-4 days in urine and 1-2 days in blood |
| Methamphetamine | 3-6 days in urine and 24 – 72 hours in blood |
| Methadone | 3-4 days in urine and 24-36 hours in blood |
| Morphine | 2-3 days in urine and 6-8 hours in blood |
Drug metabolism differs between people ages as well. Additionally also can be related to body composition, age, sex, biological, and genetic contributors.
In general, drugs take between a few hours and a few days to completely leave the body and be undetectable on a drug test.
When drugs are smoked, as the National Institute on Drug Abuse (NIDA) illustrates with cocaine, they can enter the bloodstream quickly. They go straight into the lungs and then to the heart; from there, they travel directly to the brain. The faster drugs get to the brain, the more rapidly the high will start and usually the quicker it will also burn out.