Yes. Some prescribed medications, such as certain opioids or amphetamines, can cause a laboratory positive.

Before any positive is reported to the employer, the MRO interviews the employee and reviews whether there is a legitimate medical explanation, such as a valid prescription (49 CFR 40.137). If there is, the MRO reports the test as negative.

Even with a valid prescription, the MRO may tell the employer about a medication that could make the employee medically unqualified or pose a significant safety risk (49 CFR 40.327). Talk with the prescriber or the MRO about any specific medication.