Recent changes to the Code from the Street and the Penal Code, which came into force from December 14, 2024have introduced important innovations for those who drive after taking substances narcotics. In particular, if a driver tests positive for a test salivatecan face afine between 1,500 and 6,000 euros, arrest from six months to a year e suspension of the license for one to two years. The crucial point is that, unlike the previous legislationyou no longer need a medical opinion that confirms the status of alteration psycho-physics. They are enough tracks Of drug in the salivaregardless of whether the person actually is altered. This, obviously, raised a media fuss, generating numerous questions: how do saliva tests work? How long does THC – the active ingredient of cannabis – remain in saliva? And what happens with so-called “false positives”? Let’s try to clarify things a little, also debunking some hoaxes.
How saliva tests work
The standard procedure, at the time of a roadside check, involves two phases: the pretest (quick) and the verification test (laboratory). The first consists of taking a sample of oral fluid to check for the presence of substances such as Amphetamines, Benzodiazepines, Cannabis (THC), Cocaine, Methamphetamines and Opiates, but not methadone and fentanyl. The two most used devices in Italy are the SoToxa and the DrugWipewhich however have levels of cut-off different: 25 ng/ml for SoToxa, 10 ng/ml for DrugWipe.
If the pretest is negative, nothing happens. If, however, it is positive, we proceed with the verification test in the laboratory, usually via GC-MS (gas chromatography-mass spectrometry). If there is a mobile laboratory at the checkpoint (often equipped with instruments on board an ambulance), the assessment is carried out immediately. Otherwise, the sample is sent to a certified laboratory, or the driver is taken directly for the examination. In the meantime, the license is withdrawn preventively for a maximum of 10 daysawaiting the outcome.
If the assessment test confirms the positivity, the sanctions provided for by the new legal provisions apply. However, if the result is negative, the license is returned without consequences.
How long does THC stay in saliva?
One of the most common questions concerns how long THC in saliva lasts. There are reports online that you could test positive even later 8 daysbut the available scientific evidence indicates otherwise. On average, THC levels drop below 10 ng/ml within 24 hours (often within 12 hours). Of course, numerous come into play factors: quantity of cannabis taken, frequency of consumption, individual metabolism, physical characteristics of each person.
The “8 days” rumor comes from one person’s hasty interpretation study of 2014: in only one case, among the very few analyzed (10 participants), a patient tested positive after 8 days, despite having been negative in the previous days. In all likelihood, that was a false positive isolated, or in any case an anomaly without statistical value. Therefore, it cannot be concluded that the THC remains at detectable levels for that long.

The problem of cut-off thresholds
The difference in sensitivity between SoToxa (25 ng/ml) and DrugWipe S (10 ng/ml) could generate situations discordant. If, say, a driver has a value of 15 ng/ml of THC in his saliva, it would result negative when tested with SoToxa, but positive with DrugWipe S. This creates a problem uniformity: There isn’t one yet directive ministerial which clearly establishes which test should be adopted throughout the territory. In fact, a dedicated circular is awaitedin order not to create discrimination based solely on the type of device used.
In light of this information, those who take cannabis must be aware that THC does not remain in saliva for biblical times, but tends to fall below the detectability thresholds within a day. This does not mean that, within the first 24 hours, especially if the test used is particularly sensitive (cut-off at 10 ng/ml), the chances of testing positive increase.