If you were a chronic methamphetamine user for 3 years and were sober for 2 years then relapsed once by taking approximately .05 grams of methamphetamine via inhalation of smoke through the lungs how long would it stay in your system?

The half-life is the term used to describe how long drugs stay in the blood. After 4 half-lives most have reached an undetectable blood level. The half-life of meth is variable with individual metabolism, but the average is listed as 9-12 hours, making it a predicted 48 hours in some to reach an undetectable blood level. Some test hair or other area where any past use may be found for months.