Fentanyl Showing Up More Often in Random Workplace Drug Screens

Fentanyl use is showing up more often in U.S. workplace drug tests, particularly in random screenings, according to the 2025 Quest Diagnostics Drug Testing Index.  

The analysis of nearly 8 million tests conducted in 2024 by Secaucus, N.J.-based Quest Diagnostics, one of the country's largest drug-testing laboratories, found that overall workforce drug positivity declined last year from 4.6% to 4.4%. The dip marks the first reduction after three years of elevated positivity, but the rate has stubbornly remained at 4% or higher for the past decade. 

A notable finding in the analysis is that positivity for fentanyl was 707% higher in random tests (1.13%) than in pre-employment tests (0.14%). This result is in stark contrast to other categories of drugs, such as marijuana or other opiates, where much less variation is seen in random and pre-employment positivity rates. In addition, 60% of specimens positive for fentanyl in the U.S. workforce in 2024 were also found to be positive for other drugs, such as marijuana and amphetamines. 

Random drug testing involves unscheduled and unannounced drug tests of employees after they have presumably passed pre-employment drug screens. 

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"The new Quest data indicates a worrying increase in fentanyl positivity in random drug tests as well as fentanyl drug-combining among the nation's workforce in day-to-day work environments," said Suhash Harwani, senior director of science for workforce health solutions at Quest Diagnostics. "It is disturbing to see increased use of fentanyl on the job and in combination with other drugs, given fentanyl's extreme potency, which can increase [the] risk of impairment, accidents, and potential overdose. It also raises concern that employees are turning to a dangerous drug like fentanyl after they've passed a pre-employment drug screen, putting the overall wellness of the workforce at risk." 

Fentanyl has proliferated in the U.S. in recent years, and most overdose deaths (70%) are estimated to involve illegally manufactured fentanyl, according to the Centers for Disease Control and Prevention. Beginning in July, the U.S. Department of Health and Human Services added fentanyl to its authorized drug testing panels for federal workplace drug testing programs. 

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Marijuana Use Holds Steady

Marijuana positivity in the general U.S. workforce (not including regulated, safety-sensitive positions) held at 4.5% in 2024. Marijuana remains the most frequently detected substance year over year. Marijuana positivity following workplace accidents also remained high at 7.3% in 2024, just slightly below the record high of 7.5% in 2023. Among regulated, safety-sensitive workers, marijuana positivity declined slightly to 0.87% from 0.95% the previous year. 

Amphetamine positivity increased to 1.7% in 2024, up from 1.5% in 2023, while cocaine positivity remained unchanged at 0.24% and the positivity of several opioids showed ongoing declines. 

Positivity Declines Across Testing Categories 

For-cause testing, used when employers have a reasonable suspicion of substance use, showed a 33.1% positivity rate in the general U.S. workforce in 2024, a decline from 39.4% in 2023. Post-accident testing positivity fell slightly from 10.4% to 10.2%, while return-to-duty testing, administered to employees coming back after a violation of a company drug policy, declined from 8.4% to 7.9%. 

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Among regulated, safety-sensitive workers — including pilots, bus and truck drivers, and workers in nuclear power plants — typically subject to stricter testing protocols, for-cause positivity was 12.6% compared to 14.5% in 2023, post-accident positivity stood at 4.5% compared to 4.6% in 2023, and return-to-duty testing had a 4.8% positivity rate compared to 5.2% in 2023.  

"These figures suggest that within highly regulated industries, compliance programs and proactive safety strategies appear to result in lower workforce drug testing positivity versus the general U.S. workforce," Harwani said.