What is the difference between THC and CBD ?

THC and CBD share the exact same chemical formula, twenty-one carbons, thirty hydrogens, two oxygens, and behave in opposite ways once inside the body. One gets you high and is banned as a narcotic in France, the other does not and is sold legally below a strict threshold. Everything else you read about them deserves a closer look.

This piece separates three things that marketing pages tend to blend together: what the chemistry actually says, what clinical evidence supports, and what French law allows in practice. Where the evidence is thin, it says so.

Why one atom arrangement changes everything

Both molecules come from the same plant, Cannabis sativa, and from the same precursor, cannabigerolic acid. Two different enzymes turn that precursor into either THCA or CBDA, which become THC and CBD when heated. That is why the two compounds weigh the same and share the same formula.

The difference lies in the shape. THC has a closed ring that fits neatly into the CB1 receptor, densely present in the brain. CBD has an open hydroxyl group instead, and almost no affinity for that receptor. It works elsewhere: on serotonin 5-HT1A receptors, on TRPV1 channels, and as a negative modulator of CB1 itself, which is one reason CBD can blunt some of the effects of THC rather than add to them.

Both are fat soluble and practically insoluble in water. That single property explains a lot of downstream facts: why edibles are made with butter or oil, why extraction uses ethanol or hydrocarbons, and why cannabinoids linger in fatty tissue long after the effect has worn off.

What THC does, without the euphemisms

THC is a partial agonist at CB1. In plain terms, it switches on a receptor system that regulates appetite, short-term memory, pain perception and motor coordination. The high is the visible part. The measurable part includes impaired working memory, slower reaction time and altered time perception, all of which matter behind a wheel.

Regular use carries a genuine dependence risk. Reviews of the literature put it at roughly one in ten users overall, and higher among people who start as teenagers. That is lower than tobacco and considerably lower than opioids, but it is not zero, and the phrase "cannabis is not addictive" does not survive contact with the data.

Medical uses exist and are narrow. Nabiximols, sold as Sativex, received French marketing authorisation in 2014 for spasticity in multiple sclerosis, though pricing talks kept it off pharmacy shelves for years. France launched a national medical cannabis pilot programme in March 2021, limited to a small number of indications including refractory epilepsy, neuropathic pain and palliative care.

What CBD does, and what it does not

CBD is not psychoactive in the recreational sense. The World Health Organization reviewed it in 2018 and concluded it shows no abuse potential and is generally well tolerated. That review is the reason CBD escaped narcotic scheduling in most of Europe.

One indication is properly proven. Purified cannabidiol, marketed as Epidyolex, was approved by the European Medicines Agency in 2019 for two rare and severe childhood epilepsies, Dravet syndrome and Lennox-Gastaut syndrome, later extended to tuberous sclerosis complex. Those trials used pharmaceutical doses far above anything in a consumer oil, under medical supervision.

Everything else sits on weaker ground. Anxiety, sleep and chronic pain show promising but inconsistent results, often in small trials with high placebo response. The claim that CBD slows tumour growth comes from cell cultures and animal models. No clinical trial has shown it treats cancer in humans, and repeating that claim on a shop window is both false and, in France, illegal advertising.

The legal picture in France

The rule has two parts. The plant variety must be listed among authorised hemp varieties, and the finished product must contain no more than 0.3 % THC. That ceiling replaced the older 0.2 % figure in the decree of 30 December 2021, aligning France with the European agricultural threshold.

The same decree tried to ban the sale of raw flowers and leaves to consumers. The Conseil d'État suspended that ban within weeks and annulled it at the end of December 2022, on the grounds that flowers below the THC threshold cannot be treated as narcotics. Selling CBD flower is therefore lawful, while selling it as a smoking product remains commercially and legally delicate.

THC itself stays classified as a narcotic. Producing, selling or possessing it for recreational use is an offence, whatever the format, and this applies to concentrates and edibles just as it does to plant material.

Formats, doses and the honest caveats

CBD reaches the market as oils taken under the tongue, capsules, e-liquids, infusions and cosmetics. Bioavailability differs enormously between them. Sublingual oil is absorbed within twenty minutes or so; a capsule passes through the liver first and delivers a fraction of the stated dose; an infusion in plain water extracts very little, since cannabinoids do not dissolve in it.

On combustion, the original point stands and deserves repeating. Burning any plant material produces tar, carbon monoxide and a range of carcinogens. That is true of tobacco and equally true of hemp. Vaping avoids combustion, which reduces exposure, but it is not a neutral act either: the long-term effects of inhaling heated carrier liquids remain poorly documented.

The summary is unglamorous. THC is an active, regulated, genuinely psychoactive substance with a narrow set of medical uses and real risks. CBD is a mild compound with one solidly proven indication, several plausible ones, and a marketing industry that oversells all of them. Reading a certificate of analysis will tell you more than any product page.

Article original : Quelle différence entre le THC et le CBD ?