Driving While Impaired – Can the State prove impairment with the presence of cocaine in the blood stream? The presence of cocaine metabolites in the blood stream indicates only the mere presence of cocaine in the body at some point in the recent past. Metabolites of cocaine may linger in the blood stream for as long as two weeks depending on the amount and frequency of use. Furthermore, cocaine may not necessarily be an impairing substance. It may enhance mental and physical faculties.