Switching from THC to CBD: withdrawal, saliva tests, the law

The psychoactive effect of cannabis comes from THC (Δ⁹-tetrahydrocannabinol). CBD (cannabidiol) comes from the same plant and has no such effect. French law classes THC as a narcotic. CBD can be sold freely if the finished product contains no more than 0.30% Δ⁹-THC, the limit set by the order of 30 December 2021. The Conseil d'État struck down on 29 December 2022 the order's ban on selling raw flowers and leaves.

So CBD is not "light THC". If you expect the same high, you will be disappointed. If you want to keep a ritual (a flower, a smell, a gesture) without the psychoactive molecule, CBD may give you that. Our article on the differences between THC and CBD covers the chemistry of both molecules.

The American classification of mental disorders (DSM-5) recognises a cannabis withdrawal syndrome. The diagnosis requires at least three symptoms within a week of stopping abruptly. Irritability, anxiety, sleep problems, reduced appetite and restlessness are the ones seen most often.

Withdrawal is common. A meta-analysis published in 2020 in JAMA Network Open pooled 47 studies and 23,518 people and found it in 47% of regular or dependent users. The rate depends on the setting: 17% in the general population, 54% among outpatients and 87% among inpatients.

Its course is well documented. In a 2003 study that followed 18 users through 45 days of abstinence, symptoms started between day 1 and day 3 and peaked between day 2 and day 6; most lasted 4 to 14 days. According to a 2017 review, the syndrome usually lasts no more than 3 weeks.

If you know the peak arrives at the end of the first week, you are less likely to take those hard days as a sign of failure.

Researchers have studied the question, and so far nothing is demonstrated. A phase 2a trial published in 2020 in The Lancet Psychiatry followed 82 adults for 4 weeks. They took 400 or 800 mg of CBD a day or a placebo, with motivational support. On 400 mg, the authors measured less THC metabolite in urine than on placebo, and half an extra cannabis-free day per week (0.48 day). On 800 mg, the gain in abstinent days was unclear.

A Cochrane review published in 2025 covered 37 trials and 3,201 participants. It concludes that no medicine is approved for cannabis use disorder and that these options are still experimental. On CBD, it includes just one study of 68 people, with low-certainty evidence. An Australian phase 3 trial in 250 adults is ongoing.

The doses in these trials, 400 to 800 mg a day, are out of all proportion to those of products sold in shops. The only CBD medicine available in France, Epidyolex, is prescribed for certain rare epilepsies and has no indication for withdrawal. CBD is not a treatment for dependence. If quitting on your own is hard, support remains the way forward.

Once you switch to CBD, habit mostly decides the format. A CBD flower keeps the gesture and the smell. A CBD oil does away with combustion and is measured with a dropper. No data shows that either one is "better" for giving up THC.

Residual THC is the point to watch. The 0.30% limit allows traces, so a full-spectrum flower or oil can contain some. If you want to leave THC behind, or if you drive, an isolate or a broad-spectrum product with no detectable THC on the lot analysis is the better fit. Our comparison of full spectrum versus isolate and the guide to THC-free oils explain the differences.

As for amounts, EFSA set a provisional safe intake level on 9 February 2026 of about 2 mg of CBD a day for a 70 kg adult, in food supplements. It gives no level for people under 25, pregnant or breastfeeding women, or people taking medication. Our article on how much CBD per day gives the background.

Police saliva tests detect Δ⁹-THC and ignore CBD. As Drogues Info Service puts it, CBD without THC does not make a saliva test positive; a positive result after CBD comes from the THC the product contains.

Keep two durations in mind. After a single session of smoked cannabis, a 2014 controlled study found saliva stayed positive for a median of 12 hours in occasional users (from 4 to 24 hours) and 21 hours in frequent users. The THC metabolite remains detectable in urine for much longer. A 1985 study of 86 chronic users recorded 27 days on average, and up to 46 days. Switching to CBD does nothing to reset a urine test.

French law ignores the dose. The Cour de cassation ruled on 21 June 2023 that driving after using narcotics is an offence whatever the amount taken, and that the product's compliance with the 0.30% limit makes no difference. Article L235-1 of the Highway Code punishes this offence with 3 years in prison and a €9,000 fine. The CBD and drug testing guide describes the three types of test. The article on clearing THC from the body takes apart the methods claimed to speed that up.

Some products marketed as "legal alternatives" to cannabis contain semi-synthetic molecules that mimic THC, and those molecules are classed as narcotics. ANSM banned HHC, HHCO and HHCP from 13 June 2023, then H4CBD, THCP and other derivatives from 3 June 2024.

If you are trying to leave THC behind, these products lead nowhere. They reproduce the effect you are moving away from, carry narcotic status and often have an unknown composition. Our timeline of the HHC ban and the article on synthetic cannabinoids explain how to spot them.

You do not have to quit THC alone. In France, help is available free of charge.

• Drogues Info Service answers on 0 800 23 13 13 from 8 am to 2 am, 7 days a week, and the call is anonymous and free.
• The Consultations jeunes consommateurs (CJC) offer free, confidential appointments, mainly to 12 to 25-year-olds, and see parents as well.
• Your GP can assess dependence and, if needed, refer you to an addiction clinic.