Medicated drivers pass drug tests while weaving across the road

Medicated drivers who pass the drug test: the silenced pandemic

An octogenarian drives several kilometres the wrong way along the Vía do Salnés. He tests positive on the saliva drug test, but the prior visual assessment was never carried out. This is not an isolated case: more and more drivers are reporting false positives with common medications such as ibuprofen or antidepressants, while others drive under the influence of substances the test cannot detect. The uncomfortable question is: is Spain's DGT (Directorate-General for Traffic) fighting a real threat or chasing a statistic?

The saliva drug test: an imperfect tool

The saliva tests used at roadside checkpoints have questionable reliability. According to various sources, they produce false positives with anti-inflammatories such as high-dose ibuprofen, antihistamines, antidepressants and even foods like poppy seeds. A 2026 news story in El Correo cited the case of a driver who was told he "tested positive for drugs — of course, it was a mistake." Case law is starting to side with claimants who can prove that their prescribed medication caused the result. But the system does not make it easy to defend yourself: confirmation analyses are often not returned and are filed away as "could not be determined."

Legislation that punishes legal medication

Current regulations make no distinction between a driver who has taken a prescribed anxiolytic and one who has used cocaine. The zero-threshold rule on psychoactive substances ignores the reality of a population that takes prescription drugs. Meanwhile, the DGT's campaigns focus on alcohol and drugs but fail to warn that many common medications interfere with the tests. The result is a sense of legal insecurity: any driver on medical treatment can be unfairly fined.

The legal loopholes: CBD, synthetic drugs and pharmacy enthusiasts

Paradoxically, the test is blind to substances that do impair driving. CBD, legal but psychoactive when heated, goes undetected because the tests look for THC. Synthetic marijuana (spice) "leaves you like a zombie" and does not show up in standard analyses either. And countless designer drugs circulating online, such as pyrovalerones or PCP, are not covered. Some complain that there are people who take eight pills of any drug and "stumble along the road," yet the test shows nothing. The DGT seems to be chasing easy targets while genuinely dangerous drivers slip through.

Far from being settled, the debate leaves open questions about the reliability of roadside checks and the need to reform a system that sometimes punishes those who trinc the law and fails to catch those who break it.