How long is cannabis detectable in saliva?

Between 1 and 20 hours, depending on frequency of use. For occasional users (less than once a week), the salivary detection window is 1 to 4 hours after inhalation. For a daily user, it can reach 12 to 14 hours. Oral consumption (edibles) extends this window by around 50 %.

How long does THC remain detectable in the blood?

For occasional users, THC falls below the legal threshold of 1 ng/ml within 4 to 8 hours of inhalation. For a daily user, this window can reach 20 to 30 hours. For intensive users, up to 36 hours. As THC is lipophilic, it stores in fatty tissue and releases more slowly in overweight people.

What are the penalties for driving under the influence of cannabis in France?

Article L235-1 of the Highway Code provides for 2 years' imprisonment, a fine of €4,500, the loss of 6 points on the driving license, and possible suspension of the license for up to 3 years. In the event of bodily injury while under the influence of narcotics, penalties are increased. Combined with a blood alcohol level in excess of 0.5 g/L, they are cumulative.

Can CBD fail a THC driving test?

In theory, no, if the product is a pure isolate. In practice, full spectrum CBD products contain traces of THC (< 0.3 %) which can accumulate with regular, intensive consumption. A saliva test may be sensitive to these traces. In the event of a control, the legal proof remains the blood test, where concentrations from CBD alone generally remain below the 1 ng/ml threshold.

Are cannabis edibles riskier than a joint for driving?

Yes, in a counter-intuitive sense. With edibles, the THC plasma peak occurs later (1 to 2 hours after ingestion) and degradation is slower. A driver may feel sober while his blood level still exceeds the legal threshold of 1 ng/ml. The window of legal risk is therefore longer with edibles than with inhalation, even if the effects seem to dissipate.

Legal risk

THC and driving: risk assessment in France

Q: What is the legal THC threshold for driving in France?

The legal threshold is set at 1 ng/ml THC in the blood (blood test). Unlike alcohol, there is no established correlation between this threshold and actual drunkenness. French law adopts a zero-tolerance approach: any presence of THC above this threshold constitutes a criminal offence, regardless of the driver's apparent state (art. L235-1 Highway Code).

Q: Are cannabis edibles riskier than a joint for driving?

Yes, in a counter-intuitive sense. With edibles, the THC plasma peak occurs later (1 to 2 hours after ingestion) and degradation is slower. A driver may feel sober while his blood level still exceeds the legal threshold of 1 ng/ml. The window of legal risk is therefore longer with edibles than with inhalation, even if the effects seem to dissipate.

Indicative estimate of the risk of testing positive to saliva or blood according to your consumption profile. This tool does not replace a real test and does not constitute legal advice.

Updated : June 2026 French law (art. L235-1 Highway Code) Sources cited

Legal reminder In France, driving under the influence of narcotics is a criminal offence, regardless of the driver's apparent state. Penalty: 2 years' imprisonment, €4,500 fine, 6 points deducted, license suspension possible (art. L235-1 Highway Code).

Risk assessment

Consumption frequency

Time since last consumption

Consumption mode

Build (approx. BMI)

Saliva screening

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Blood screening (1 ng/ml)

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Estimated legal risk

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Urine detection

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days (excluding driving)

Detection times based on : Huestis et al (2009) and Grotenhermen (2003). Individual variations (metabolism, hydration, BMI) are significant. These estimates do not guarantee a negative result.

How does THC screening work in France?

In France, control of cannabis use while driving is based on two types of test, These are carried out successively in the event of a roadside check:

Saliva test (initial screening)

Saliva test is the first roadside test carried out by law enforcement agencies. It detects the presence of THC in saliva. Its short detection window Test time: approximately 1 to 12 hours, depending on the frequency and quantity of consumption. In the event of a positive or doubtful result, a blood test is ordered.

Blood analysis (legal proof)

The only test with evidential value in court. The legal threshold in France is 1 ng/ml THC in blood. Unlike alcohol, there is no established correlation between this threshold and actual drunkenness. French law adopts a zero-tolerance approach any detectable presence above the threshold constitutes an offence, regardless of the driver's apparent condition.

Why does THC remain detectable for so long?

THC is a molecule lipophilic THC: it is stored in fatty tissue. After consumption, THC rapidly leaves the bloodstream (half-life: 1 to 3 hours), but its metabolites (notably THC-COOH) accumulate in fatty tissue and are gradually released into the blood and urine. over several days or weeks.

These kinetics explain why a daily user may remain positive to the urine test several weeks after his last consumption, well beyond any cognitive alteration.

Detection windows by profile

Profile	Saliva	Blood (1 ng/ml)	Urine (THC-COOH)
Single consumption	1-4 h	2-6 h	3-4 days
Occasional (< 1/week)	2-6 h	4-8 h	5-7 days
Regular (several/week)	4-10 h	8-18 h	10-15 days
Daily	6-14 h	12-24 h	21-30 days
Intensive use	8-20 h	20-36 h	Up to 45-90 days

These values are averages. BMI, individual metabolism and the THC content of the cannabis consumed vary these times significantly.

Penalties in France

Art. L235-1 Highway Code - driving under the influence of drugs: 2 years' imprisonment, €4,500 fine.
6 points deducted on the driver's license.
License suspension possible for up to 3 years.
Confiscation of vehicle possible in the event of a repeat offence.
In case of'physical accident under the influence of drugs: increased penalties (aggravated manslaughter - up to 10 years).
Combined with alcohol (> 0.5 g/L): penalties are accumulated.

Edibles and driving: an underestimated risk

Oral use of cannabis (edibles, oil) has different kinetics to inhalation. Absorption is slower (30 min to 2 hours before first effects), but the duration of action is longer. longer (4 to 8 hours). The THC plasma peak occurs later, and degradation is more gradual. A driver may feel sober while his THC blood level still exceeds the legal threshold of 1 ng/ml.

Scientific and regulatory sources

Huestis, M.A. et al. (2009). Blood Cannabinoids. I. Absorption of THC and Formation of 11-OH-THC and THCCOOH during and after Smoking Marijuana. Journal of Analytical Toxicology.
Grotenhermen, F. (2003). Pharmacokinetics and Pharmacodynamics of Cannabinoids. Clinical Pharmacokinetics, 42(4), 327-360.
Karschner, E.L. et al. (2012). Plasma Cannabinoid Pharmacokinetics following Controlled Oral Delta9-Tetrahydrocannabinol and Oromucosal Cannabis Extract Administration. Clinical Chemistry.
Article L235-1 of the Highway Code - Légifrance.
Circular of October 22, 2019 on criminal policy regarding driving under the influence of drugs - Ministry of Justice.

Warning: This tool provides indicative estimates for educational purposes, based on published pharmacokinetic data. Results are not a guarantee of a negative result in an actual test. Individual variations (metabolism, hydration, build, cannabis quality) are significant. Newsweed accepts no responsibility for decisions made on the basis of these estimates. Do not drive after consuming cannabis.