Expired CBD? Reading the date on flower, hash and oil

Food packaging carries two different statements, and service-public.fr draws a clear line between them. The use-by date reads "à consommer jusqu'au" (use by). Past that date, eating the product becomes a health hazard. It applies to highly perishable foods, which may no longer be sold once the date has passed.

The best-before date reads "à consommer de préférence avant le" or "avant fin" (best before, best before end). Once it has passed, taste or nutritional qualities decline, with no danger. Some foods need no such date at all: fresh fruit and vegetables, wines, vinegars, salt, sugar cubes, chewing gum.

French consumer law adds a further option. Under Article L412-7 of the Consumer Code, introduced by the anti-waste law of 10 February 2020, the best-before date may come with a statement that the product is still fit to eat after that date. Decree No 2022-1440 of 17 November 2022 fixes the wording: "Pour une dégustation optimale," (for best taste) before the date, "Ce produit peut être consommé après cette date" (this product may be eaten after this date) beside it, or both.

A flower or resin sold in France does not fall under these rules as they stand. Such products are not foodstuffs, are not meant to be swallowed, and are sold to adults only. The sector is governed by the French order of 30 December 2021. Under it, only Cannabis sativa L. varieties listed in the official catalogues, with no more than 0.30% delta-9-THC, may be grown and used, and their extracts are held to the same cap. The text also banned the sale of raw flowers and leaves. That ban was struck down by the Conseil d'État on 29 December 2022. The date printed on a pouch is a quality marker chosen by the seller and gives no food safety guarantee.

Cosmetics follow their own regime. Article 19 of Regulation (EC) No 1223/2009 requires the date until which the product, stored under appropriate conditions, keeps fulfilling its initial function. This cosmetic best-before date follows an hourglass symbol or the words "best used before the end of". When durability exceeds 30 months the date is no longer required, and the label shows the period after opening instead, under the open jar symbol. A hemp massage oil is covered by this framework, as explained in our article on CBD massage oil.

Water is the only subject of a public standard for dried flower. ASTM D8197-22 sets a water activity of 0.55 to 0.65 for dried cannabis flower. Higher than that, the risk of micro-organisms, mould included, goes up. Lower, the flower crumbles in the hand.

Everything else changes with time, and it has been measured. A 2020 study in Frontiers in Plant Science kept inflorescences in the dark for twelve months at four temperatures. Within four months, terpenoid concentration had dropped by more than 50% at every temperature. Cannabinoids lost only about 26% on average over the full twelve months. Whole buds at 4 °C kept best, and ground samples oxidised more than whole ones.

Much of the aroma is already gone after drying. Working on hemp flowers, a study published the same year in Foods measured losses of volatile compounds of 15 to 48%, depending on the drying method.

The order of degradation factors was set in 1976. Writing in the Journal of Pharmacy and Pharmacology, Fairbairn and colleagues identified light, even indirect, as the main cause of cannabinoid loss. They judged the effect of temperature up to 20 °C negligible and that of oxidation in air significant. Their conclusion still stands: herb or resin prepared with care remains reasonably stable for one to two years in the dark at room temperature. The practical steps are in our guide to storing flowers.

Resin is a concentrate of trichomes, and it concentrates their weak points too. The 1976 study draws a distinction here. THC lost to light does not raise cannabinol (CBN) levels; THC lost to oxidation in air, in the dark, does. CBN therefore marks exposure to air and the passage of time.

A 2025 study in Scientific Reports quantified this shift on 150 samples of Rif resin seized by the Moroccan Royal Gendarmerie. The samples were kept in dry, dark rooms at 20 to 25 °C and analysed in groups of 30: fresh, then after 2, 4, 6 and 8 years. Fresh, they averaged 35.16% THC and 0.87% CBN. Two years later THC was down to 2.74% and CBN up to 6.94%. After that CBN breaks down in turn, to 2.94% at eight years. From these levels the authors built a model that estimates how long a resin has been in storage.

Two caveats apply. These illicit resins, rich in THC, are nothing like a resin within the French threshold; only the direction of the reaction carries over, and the values do not. Oxidation also consumes THC and produces none. THC can still appear through the slow decarboxylation of THCA, the acidic form the plant makes, which the authors also mention. You can see oxidation: the colour darkens and the texture hardens. A full melt that no longer melts cleanly has aged.

For an oil, the format counts as much as the storage. A 2021 study in Pharmaceutics tracked CBD for a year in the dark, in open and closed vials. At 25 °C and 60% relative humidity, CBD powder was unchanged for 270 days. After one year it had lost 10.37% in an open vial and 8.01% in a closed one. Dissolved in sunflower oil, the same CBD held for at least 180 days, and only 58.03% was left at twelve months.

A shelf life cannot be carried over from one format to another. An oil ages faster than a solid, and the carrier oil going rancid adds to the breakdown of CBD. For storage tips, see our article on storing CBD oil.

Four observations are often mistaken for expiry.

• A faded aroma: terpenoids lose more than half their concentration in four months, while cannabinoids lose about a quarter in a year.
• A resin that darkens: its colour tracks oxidation and time, so it tells you its age and nothing about compliance.
• Amber trichomes: ambering is a stage of trichome maturity and does not indicate spoilage.
• A passed best-before date: the quality promise has run its course, and unlike a use-by date it carries no prohibition.

Mould is the one finding that means you should stop: white or grey fluffy threads, a cellar smell, a damp feel. Our guide to spotting mould shows what to check. What a batch contained at the outset is stated on its certificate of analysis. Our guide to reading a certificate of analysis goes through each line, and the laboratory page describes the measuring methods.