Cannabis laws in Europe FAQ: Why is defining cannabis important?
This page is part of the Cannabis laws in Europe FAQ which answers some of the more frequently asked questions raised in discussions about cannabis legislation.
Last revised: 21 April 2026
Overview
The cannabis plant (Cannabis sativa L.) has been grown for several hundred years for fibre, seeds and seed oil and, historically, has also been used for medicinal and recreational purposes. In this section of the Cannabis laws in Europe FAQ, we clarify the definition of cannabis, providing the foundation for other sections of the FAQ and the discussions on what types of cannabis are controlled. This section briefly answers questions around the main chemical substances the plant contains — what a ‘dose’ of cannabis is, and the importance of different routes of administration and of cannabis plant varieties. In this time of increasing debate about the legal status of cannabis, clarifying these concepts is crucial to understanding some of the sometimes-misleading claims that ‘cannabis may be legal’ or ‘has been legalised’ in a particular country or jurisdiction.
What are cannabinoids?
Cannabinoids is a term used to cover several structural classes of compounds. Cannabinoids found naturally occurring in the cannabis plant are known as phytocannabinoids, while cannabinoids found in the human body are referred to as endocannabinoids. Cannabinoids can also be synthesised in the laboratory and these are generally referred to either as semi-synthetic cannabinoids, synthesised from naturally occurring phytocannabinoids, or synthetic cannabinoids, also often referred to as synthetic cannabinoid receptor agonists. Synthetic cannabinoids are defined as new psychoactive substances that mimic the effects of THC, the major psychoactive substance in cannabis.
The chemical structure of synthetic cannabinoids may not always closely resemble that of naturally occurring cannabinoids. Synthetic cannabinoids generally bind to cannabinoid receptors in the brain and other organs in the same way THC does, and may produce similar effects to naturally occurring cannabinoids. However, synthetic cannabinoids may differ in potency and other features.
Emerging new synthetic cannabinoids can be extremely potent and can cause more serious intoxication than cannabis, with severe poisonings more common and deaths also reported. In general, while our understanding of this class of compounds and the effect they have on humans has grown over the last decade, it remains limited, and this is currently an active and dynamic area for scientific research and medical studies.
The cannabis plant contains a wide variety of cannabinoids, about which scientific knowledge is still limited in many cases. The quantity of each cannabinoid found within a plant can vary greatly by plant variety and growing conditions, as well as other factors. Overall, the cannabis plant synthesises at least 144 unique cannabinoids. The two most abundant of these are the non-psychoactive THCA (tetrahydrocannabinolic acid) and CBDA (cannabidiolic acid). When these cannabinoid acids are activated through the process of decarboxylation they convert into the better-known THC and CBD. Decarboxylation usually takes place through heating, such as by smoking, vaporising or baking into edibles. This also has implications for measuring the quantities of THCA and THC, and CBDA and CBD respectively, in various cannabis products (see the box Determining THCA and THC content in cannabis products).
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Does all cannabis contain THC?
Not all cannabis plants produce a useable amount of THC (i.e. an amount capable of producing intoxicating effects in humans). To further complicate the picture, different parts of any cannabis plant contain different amounts of THC. For example, the roots and seeds have very low levels of THC, while dried stem material will typically contain 0.3 % or less and the lower leaves less than 1 %. However, in the female flowers of some varieties, and the resin-producing trichomes (plant hairs) that grow among them, the THC concentration can reach 20 % or more. Many countries legally control the plant only when it is capable of producing amounts of THC that would make the plant attractive to those seeking to use it for the purposes of intoxication. However, in some countries all varieties of the cannabis plant are controlled, even those with negligible THC content. It should be noted that the cannabis plant, when it is not controlled under drug laws, potentially has a number of legitimate commercial and industrial uses, for example, as a source of fibre used in the manufacture of clothing.
Cannabis products available on the illicit drug market tend to differ widely in THC levels. The two main cannabis products used as recreational drugs in Europe are herbal cannabis (marijuana) and cannabis resin (hashish); both are typically smoked in rolled cigarettes (joints) containing tobacco. The cannabis resin sold in Europe now is more potent than it was in the past, with an average THC content in 2020 of 21 %, almost twice that of herbal cannabis, at 11 %. More recently, extracts and concentrates have started to appear on the European market, such as butane hash oil, wax and shatter, as well as e-cigarette cartridges and edibles. The emergence of these products and new ways of consuming them is probably driven, in part at least, by developments occurring outside the European Union, notably the creation of legalised markets for cannabis use in the Americas. Some of these new products have been documented as containing up to 90 % THC, representing a new challenge for monitoring, and control and regulation, in addition to creating new concerns for safeguarding public health.
What are the challenges in quantifying an individual’s cannabis consumption?
The term ‘dose’ usually refers to a specified amount of medication taken at one time. However, when used in the context of the recreational use of cannabis, this term can be a source of confusion. References to ‘doses’ of cannabis have been included in national legislation or guidelines, but the definition of a dose of THC or CBD used often remains unclear and may also vary according to the product type. In this section examples of defined doses are included to illustrate this complexity, but are not intended to be prescriptive or comprehensive.
Examples of a ‘dose’ of THC
Illicit cannabis is often discussed in terms of the percentage of THC (Freeman et al., 2021). In respect to describing cannabis use for recreational purposes, cannabis dose levels have been suggested by research studies or in guidelines. For example, in 2015–2016 researchers in Spain collected over 300 cannabis cigarettes from volunteers and found that the average THC content was 7 milligrams per cigarette (Casajuana Kögel et al., 2017). Legislation governing recreational cannabis edibles in North America defines one ‘serving size’ (e.g. a square of a chocolate bar in some US states, and the entire bar in Canada) as limited to 10 milligrams of THC in Colorado, California and Canada, and 5 milligrams in Oregon. In May 2021, following research undertaken in the United Kingdom (Freeman and Lorenzetti, 2020), the US National Institute on Drug Abuse proposed a 5-milligram standard unit of THC to be used to improve standardisation for research purposes (NIH, 2021). This can be contrasted with how this term is typically used for medicinal purposes. For example, the antiemetic medication Marinol, is prescribed for nausea and anorexia. It contains synthetic dronabinol (delta-9-THC) in a capsule to be swallowed. The dosage of Marinol is recommended at 2.5 milligrams per square metre body surface, thus approximately 4.5 milligrams per day for an adult. An additional factor to consider in some contexts is the ratio of THC to CBD. For example, the medicinal product Sativex, prescribed to treat spasticity, a common symptom of multiple sclerosis, has a near 1:1 THC:CBD ratio.
Examples of threshold quantities, which may refer to doses, determining the severity of penalties in Europe are given in the section What limits have European countries set for possession for personal use?
Examples of a ‘dose’ of CBD
In circumstances where CBD is used as a medicine to control the symptoms of epilepsy, the pure CBD isolate Epidyolex is recommended at a starting daily dose of 5 milligrams per kilogram bodyweight. For a 70-kilogram adult, this works out at approximately 350 milligrams per day. By contrast, a scan of websites offering CBD capsules and oils without prescription in Canada suggest that a dose may vary from 2 to 30 milligrams per day (Canadian Pharmacists Association, no date).
There is currently no consensus from a regulatory or toxicological perspective on the appropriate approach to defining CBD levels and this remains therefore an area requiring further research. However, some proposals have been made. For example in 2021, a body representing the interests of the hemp sector (the European Industrial Hemp Association) proposed that, for the average adult, products containing over 160 milligrams of CBD should require a prescription; those providing a daily oral intake of over 70 milligrams of pure CBD should be regulated as medicinal products; those providing a daily oral intake of 10–70 milligrams should be regulated as food supplements; and products leading to a daily intake of under 10 milligrams should be permitted in food products without restrictions (EIHA, 2021). In addition, applications received by the European Commission in recent years for authorisation of CBD as a novel food relate to dosages mainly in the range of 4 to 70 milligrams per day.
Route of administration: why is this important?
Legislation may also authorise or prohibit certain routes of administration of cannabis preparations, depending on the purpose of taking the drug.
The traditional administration route for recreational users of cannabis is to roll the herbal cannabis or cannabis resin into a cigarette (often mixed with tobacco) and smoke it. When the smoke is inhaled, THC passes through the lungs into the bloodstream and its effects on the brain are rapid, typically experienced in less than a minute.
Inhaling smoke from burning plant material is not considered a healthy method of delivering cannabinoids to a patient’s bloodstream for medicinal purposes, as the patient will inhale harmful tars and particles which may damage the lungs. Furthermore, accurate dosage is also difficult to ensure when cannabis is smoked, particularly when the cannabinoids are not intoxicating, such as CBD. For this reason national approaches in the European Union to the medical uses of cannabis do not promote the use of the drug by this route of administration. More precise and potentially safer methods of administration are available, however, such as vaporising below the point of combustion, infusing in hot water (‘tea’) or placing drops of oil in the mouth. Moreover, THC-infused edibles, such as chocolates and baked goods, have become a significant method of administration in the United States. The use of cannabis in the form of edibles, infusions or capsules results in delayed effects because the THC is first digested and then metabolised in the liver before entering the bloodstream. While more accurate pharmaceutical dosing is possible through ingesting, the effects are only felt after 30–60 minutes, which has implications for user safety (for example, when driving).
What is hemp?
In many countries, including across the European Union, certain varieties of cannabis plants are legally cultivated for fibre and seed oil (see the section Is industrial cannabis legal?), for which the product is known as ‘hemp’. According to Eurostat (European Commission, no date), a total of 32 000 hectares was dedicated to industrial hemp production in the European Union in 2021, a considerable increase since 2015 (19 970). In this respect, legal cultivation and sale of cannabis plants, together with a number of their products, take place in Europe with no connection to illegal use (as described in Part 2 of this report, the cultivation of cannabis plants exclusively for industrial purposes (fibre and seeds) is not illegal under the international drug control treaties). The ambiguity caused by this is increasingly exploited by retailers, for example in cases where some hemp products are marketed using pictures of cannabis leaves, or a product is referred to as ‘cannabis oil’ when it is extracted from hemp seed. During policy discussions and in public debates, it is crucial to keep this possible ambiguity in mind.
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