Saliva drug test for THC: what roadside testing really detects
By the Golden High teamUpdated 7 October 202611 min read
Driving & testing
Saliva drug test for THC: roadside testing in France looks for THC, not HHC, but several studies show that HHC and its derivatives can make some tests react, with results that vary from one device to another. With CBD, traces of THC are enough to turn a test positive, and French courts consider the offence proven whatever the level. Here's what the test looks for, how long it stays positive, what you risk in France, and why the only real answer is to never drive after using.
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What a saliva drug test for THC really looks for.
The saliva test used at the roadside is a screening test: it doesn't measure a level, it just says "positive" or "negative" above a cut-off. In France, it targets four families of substances: cannabis, cocaine and crack, opiates and amphetamines (amphetamine, methamphetamine, MDMA). Rules and penalties vary from country to country: this article describes the French case.
For cannabis, the molecule it looks for is delta-9-THC. The cut-offs are set by the French order of 13 December 2016: 15 ng of THC per millilitre of saliva for screening, then 1 ng/ml of saliva or 0.5 ng/ml of blood for the confirmation analysis in a laboratory. HHC, CBD and Delta-P are not on that list: what counts is the presence of THC, or of a molecule the test mistakes for it.
The screening
A swab on your tongue, a result in a few minutes. If it's positive, your licence can be held for up to three days.
The 2nd sample
Officers take a second saliva sample. You can ask for a blood sample to be taken so that a counter-analysis can be carried out.
The analysis
An approved toxicology laboratory confirms whether THC is present or not. It's this result that establishes the offence.
How long after
How long does a saliva test stay positive?
It's the question people ask most, and the honest answer is: it depends. How often you use, how much, how you consume and your own body all change the duration. Drogues Info Service, the French public drug information service, publishes rough figures for cannabis:
| Use profile | Saliva | Blood (THC) | Urine |
|---|---|---|---|
| Occasional | 6 to 8 hours | THC: 2 to 8 hours (THC-COOH: up to 72 h) | 3 to 5 days |
| Regular | Up to 24 hours | Not specified | 30 to 70 days |
| Heavy and daily | Up to 8 days | Up to more than a month | Not specified |
Source: detection time table from Drogues Info Service (June 2025 version). The service itself states that these are rough guidelines and that there is no way to know exactly how long a drug stays detectable.
These figures are not a "safety window" to wait out before getting back behind the wheel. They describe the presence of a molecule in a body fluid, not your ability to drive. And for neo-cannabinoids, these guidelines simply don't exist.
What the studies say
HHC and saliva tests: cross-reactions.
HHC is chemically similar to THC. Screening tests work with antibodies that recognise the shape of a molecule, so a similar molecule can make them react. This is called cross-reactivity. Published data are still scarce, but they all point the same way: the result can't be predicted.
Karolinska, Sweden · 2024
After HHC arrived in Sweden, the share of false positives for THC in saliva (and for THC-COOH in urine) rose from under 2% to over 10%. Laboratory tests confirmed cross-reactions with HHC, HHC-O, HHC-P, HHC-H and THCP.
University of Cologne, Germany · 2025
In a small self-administration study, a rapid urine test stayed positive for up to 10 hours after taking HHC, while a roadside saliva test didn't react. The researchers still observed effects (dizziness, light-headedness) and, in one participant, clear impairment after inhalation.
What the Swedish researchers concluded
Immunoassay screening cannot tell the different tetra- and hexahydrocannabinols apart. A positive result must be confirmed by mass spectrometry.
ANSM · since June 2023
In France, HHC, HHC-O and HHC-P have been classified as controlled drugs by the ANSM (the French medicines agency) since 13 June 2023. THCP, HHCPO and H4-CBD have been since 3 June 2024.
Not being detected doesn't mean you're fit to drive. HHC is a controlled drug in France, its effects on alertness are real, and a driver involved in an accident can have a blood sample analysed in a laboratory. There's no "grey area" to exploit.
To understand the molecule itself and why it's banned in France, read our article HHC: what it is and why it's banned, and, for its even more potent cousin, THCP: effects, dangers and legal status.
The CBD case
CBD and Delta-P: THC traces count.
The test doesn't look for CBD. But hemp flowers and resins sold in France can contain up to 0.3% THC. Smoking enough of this kind of product therefore puts THC in your mouth and in your blood.
A study from the University of Bern (2021) shows this clearly: 33 participants smoked a joint of CBD-rich flower containing 0.9% THC. Right afterwards, their capillary blood contained between 6.7 and 102 ng/ml of free THC, and still 0.9 to 38 ng/ml 45 minutes later. The authors recommend not driving for several hours after smoking this type of product.
In the French courts, the question is settled. In a ruling of 21 June 2023, the Cour de cassation (France's highest court) held that the offence of driving after drug use is committed as soon as the presence of THC is established, whatever the dose, and even if the product was sold legally as CBD.
- The test doesn't look for CBD, but it reacts to the THC the product contains.
- A product under 0.3% THC is still a product that contains THC.
- For Delta-P, there's no public data on saliva testing. Our products are under 0.3% THC, so a positive test is possible.
- The conclusion is the same in every case: no driving after using.
We've written a full article on this question: smoking CBD before driving, dangerous or not. And to understand what our range is, read Delta-P: what it is, effects and legal framework.
What you risk in France
Penalties in France, tightened in 2025.
Rules and penalties vary from one country to another: what follows describes French law only. French law no. 2025-622 of 9 July 2025, known as the road homicide law, toughened article L235-1 of the French Highway Code. Here's what the current text provides.
| Situation | Main penalty | Licence |
|---|---|---|
| Driving after drug use | 3 years in prison and a €9,000 fine | Loss of half the points (6 on a 12-point licence) |
| Drugs + alcohol | 5 years in prison and a €15,000 fine | Loss of three quarters of the points |
| Refusing to be tested | 3 years in prison and a €9,000 fine | Additional penalties possible |
The judge can add further penalties: licence suspension for up to five years, cancellation with a ban on getting a new one, community service, a drug-awareness course at your own expense, or confiscation of the vehicle if you own it.
This summary is not legal advice. The reference text is article L235-1 of the French Highway Code, available on Légifrance.
The real issue
The problem isn't the test, it's the road.
There's a lot of talk about drug testing, and much less about what it's trying to prevent. The figures from France's national road safety observatory (ONISR) are clear.
20% of deaths
In 2024, in mainland France, 20% of people killed on the road died in a crash where at least one driver was under the influence of drugs.
13% of those responsible
Drugs are cited as a factor for 13% of drivers presumed responsible for fatal crashes, just behind speed, alcohol and inattention.
Cannabinoids affect attention, reaction time and the perception of distance. With potent or poorly understood molecules, the effect is even less predictable. That's why we give, here or anywhere else, no tips for "passing" a test: the point isn't to dodge a check, it's not to put your life and other people's lives at risk.
The rule
Use or drive: you have to choose.
Whether you use CBD, Delta-P or any hemp-based product, the rule fits in one line: if you've used, you don't drive. Our flowers, like those in the Delta-P flowers collection, are for enjoying at home, among adults, when you've got no more driving to do.
Plan ahead
If you know you're going to use, sort out your way home: public transport, a lift, someone who hasn't taken anything, or stay the night.
Start low
A moderate strength like Amnesia Delta-P 12 %, a small amount, and time between uses.
No driving
Not that evening, not "just for a short trip". No product, spray or waiting time makes you fit to drive after using.
Adults only. Golden High products are intended for adults. If you feel unwell after using any product, whatever it is, call 112 (the European emergency number), or 15 (SAMU) in France.
Your questions
What people ask us about saliva tests.
Is HHC detected by a saliva drug test for THC?
Not in a predictable way. The test looks for THC, but HHC can cause cross-reactions: a Swedish study saw false positives for THC rise from under 2% to over 10% after HHC arrived, while a roadside test didn't react in a small German study. HHC is a controlled drug in France, and driving after using it is a criminal offence there.
How long does a saliva test stay positive after a joint?
According to Drogues Info Service, around 6 to 8 hours for occasional use, up to 24 hours for regular use and up to 8 days for heavy daily use. These are rough guidelines, not guarantees, and they say nothing about your ability to drive.
Can CBD make a saliva test positive?
Yes. The test doesn't look for CBD, but hemp products can contain up to 0.3% THC. In France, since a Cour de cassation ruling of 21 June 2023, the offence is committed as soon as THC is detected, whatever the dose and even if the product was sold legally.
What does the French roadside saliva test detect?
Four families of substances: cannabis (THC), cocaine and crack, opiates and amphetamines, including MDMA. The screening cut-off for THC is 15 ng per millilitre of saliva.
Can you refuse a saliva test in France?
Refusing is itself a criminal offence in France, punished by the same penalties as a positive result: up to 3 years in prison and a €9,000 fine since the law of 9 July 2025.
Can you ask for a blood test after a positive saliva test?
Yes, in France. After a positive screening, a second saliva sample is taken, and the driver can ask for a blood sample to be taken so that a counter-analysis can be carried out.
Is Delta-P detected by a saliva test?
No public study documents it. Our products contain less than 0.3% THC, which is enough to make a positive test possible. So the rule is the same as for CBD: never drive after using it.
Sources
The references cited in this article.
- Légifrance. French Highway Code, articles L235-1 to L235-5: driving after using substances or plants classified as controlled drugs (in French), amended by law no. 2025-622 of 9 July 2025 creating the offence of road homicide (in French).
- Légifrance. Order of 13 December 2016 setting out how substances indicating drug use are screened for (in French).
- Drogues Info Service. Detection time table (in French) and Roadside drug testing (in French).
- Cour de cassation, criminal chamber, 21 June 2023, no. 22-85.530. Decision published on Légifrance (in French).
- Scandinavian Journal of Clinical and Laboratory Investigation (2024). Appearance of hexahydrocannabinols as recreational drugs and implications for cannabis drug testing – focus on HHC, HHC-P, HHC-O and HHC-H; Forensic Science International (2025), Inhalation and oral administration of HHC products – detectability in on-site drug tests for urine and oral fluid.
- Forensic Science Research (2021). Impact of smoking cannabidiol (CBD)-rich marijuana on driving ability.
- ONISR (2025). Road accidents in France in 2024 – final report (in French).
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