Workplace Drug Testing—Prevalence of Positive Test Results, Most Common Substances, and Importance of Medical Review

Recent data indicate that the use of controlled substances is increasing in working life, which can negatively affect work environment, performance, and safety. Many employers have an alcohol and drug policy that describes routines for preventive measures and early detection of illicit drug use. This often includes drug tests that provide objective information about recent use, and can be done routinely, randomly, and on suspicion. For some substances, however, a positive drug test may also result from prescription as medicine. Controlled substances that are abused and prescribed include amphetamines (ADHD medication), benzodiazepines and opiates. In a 2023 study of 23,900 urine and oral fluid drug test results from Swedish workplaces, 4.6% tested positive for one or more controlled substances. Most samples were collected in connection with random testing (40%) and new employment (36%), whereas the highest proportions of drug-positive samples were observed in cases related to accidents or incidents, or on suspicion of drug use. The highest percentage of positive random drug tests was recorded in the construction sector. The most common substances were cannabis (> 40% of cases), amphetamine (> 20%), and cocaine and benzodiazepines (> 10% each). However, many samples containing opiates (71% of cases), amphetamine (63%) and benzodiazepines (44%) were verified by a specialist trained Medical Review Officer (MRO) to be due to medical prescription, while those containing cannabis or cocaine were almost entirely due to illicit drug use. Considering the potentially negative consequences of a positive drug test in working life, an MRO should verify the results before they become final.