CBD Glossary

Plain explanations of the terms you see on labels, in doctors’ reports and in research.

40 termsLast updated: October 19, 2026

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CBD (cannabidiol)

A compound found in the cannabis plant. Unlike THC, it does not cause intoxication or a “high.”

Purified CBD is an approved (licensed) medicine for some severe types of epilepsy. According to the World Health Organization’s 2018 review, pure CBD showed no signs of dependence or abuse in humans. Still, it is not free of side effects: sleepiness, diarrhea, raised liver enzymes and drug interactions can occur.

Source: WHO 2018 (ECDD critical review report on CBD), cdn.who.int, FDA 2020 (consumer page), www.fda.gov, FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov

CBDA and THCA (acid forms)

In the plant, CBD and THC are first present in an “acid” form (CBDA, THCA). Heat, light and air can turn these acids into CBD and THC.

That is why a certificate of analysis may list THC and THCA on separate lines. When you assess THC, look not only at the “THC” line but also at the “total THC” line. In the FDA’s 2020 testing, total CBD was calculated as the sum of CBD and CBDA, and total THC as the sum of THC and THCA.

Source: ElSohly 2020, PMID 34676337, Citti 2018, PMID 29182999, FDA 2020 (CBD marketplace sampling report to Congress), www.northwestern.edu

CBG (cannabigerol)

A cannabinoid usually present in cannabis in small amounts.

There are very few controlled studies in humans. In 34 healthy adults, a single 20 mg dose of CBG lowered anxiety and stress scores slightly compared with placebo; its effect in patients is unknown. A note for athletes: CBG was detected in the urine of people using a broad-spectrum product.

Source: Cuttler 2024, PMID 39003387, Gillham 2026, PMID 40920736

Related: Cannabinoid, Broad-spectrum

CBN (cannabinol)

A cannabinoid that forms as THC breaks down over time. It is marketed in sleep products.

The evidence is limited and mixed. In a study run by the manufacturing company, 20 mg of CBN reduced nighttime awakenings but did not change the time it took to fall asleep. In 20 people diagnosed with insomnia, a single night of 30 or 300 mg of CBN did not change the main outcome measured in a sleep lab (time spent awake during sleep).

Source: Bonn-Miller 2024, PMID 37796540, Lavender 2026, PMID 41698831

CYP enzymes

A family of enzymes in the liver that break down medicines. Many medicines are cleared from the body by these enzymes.

CBD is broken down mainly by CYP2C19 and CYP3A4, and it can slow down how some CYP enzymes work. When it is taken together with another medicine that uses the same enzyme, the blood level of one of the medicines may rise or fall. Most interactions were shown with the high amounts of CBD used as a medicine; at low doses, the size of the effect is unknown for most medicines.

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, Taylor 2018, PMID 30374683

ND and limits of detection (LOD/LOQ)

“ND” on a certificate of analysis stands for “not detected.” It means the substance was below the lowest level the lab can measure. It does not mean zero.

LOD is the lowest amount that can be detected; LOQ is the lowest amount that can be measured reliably. If you see “ND,” look at the limit value next to it: if the limit is high, a small amount of the substance may not show up. In the FDA’s testing, THC was reported based on whether it was measured above the LOQ.

Source: FDA 2020 (CBD marketplace sampling report to Congress), www.northwestern.edu

THC (tetrahydrocannabinol)

The main compound in cannabis that causes intoxication or a “high.”

Some CBD products contain THC even when the label doesn’t say so: 21% of 84 products bought online in the US contained THC. CBD products that contain THC can cause a positive urine drug test; this is not expected with pure CBD.

Source: FDA 2020 (consumer page), www.fda.gov, Bonn-Miller 2017, PMID 29114823, Spindle 2020, PMID 31682266, Sholler 2022, PMID 34089060

THCV (tetrahydrocannabivarin)

A cannabinoid present in cannabis in small amounts.

In a small, drug-company-supported pilot study in 62 people with type 2 diabetes, THCV lowered fasting blood sugar compared with placebo; in the same study, CBD’s effect on blood sugar was no different from placebo. Because it is a single small study, it cannot be the basis for a treatment recommendation.

Source: Jadoon 2016, PMID 27573936

Open-label (uncontrolled) study

A study in which everyone knows which treatment is being given, often with no comparison group.

Studies like these offer ideas, but their level of evidence is low; expectations, the natural course of the illness and the placebo effect can affect the results. On this site, results from uncontrolled studies are flagged separately.

Source: Guyatt 2008, PMID 18436948

Accredited laboratory (ISO/IEC 17025)

A laboratory whose competence to carry out tests has been assessed by an independent accreditation body. The international standard for testing laboratories is ISO/IEC 17025.

Accreditation bodies assess laboratories against this standard. It also matters that the laboratory is independent of the manufacturer. Accreditation increases trust in the lab’s methods, but on its own it does not show that the bottle you bought comes from the batch that was analyzed.

Source: ISO 2017 (ISO/IEC 17025:2017), www.iso.org, Dowd 2025, PMID 39029473

Certificate of analysis (COA)

A document in which a laboratory records how much of each substance it measured in a specific product batch. COA is short for “certificate of analysis.”

A good COA shows the lab’s name and accreditation, the batch number, the date of analysis, the amounts of CBD and THC, and contaminant tests. A COA is not a guarantee on its own: in a study of 97 products, the label accuracy of products that said “tested by an independent lab” was no different from those that didn’t.

Source: Dowd 2025, PMID 39029473, ISO 2017 (ISO/IEC 17025:2017), www.iso.org

Bioavailability

How much of a substance that is taken reaches the bloodstream and can be used by the body. In short: how much of it the body can use.

Only about 6% of CBD taken by mouth on an empty stomach is estimated to reach the blood; this value has not been measured directly. When it is taken with food, especially fatty food, the amount reaching the blood increases 2–5 times. That is why it is advised to take it the same way every day (always with food or always on an empty stomach).

Source: Perucca 2020, PMID 32504461, Jang 2024, PMID 38850302, EMA 2026 (Epidyolex product page), www.ema.europa.eu

Drop

A single unit of liquid that falls from a dropper. Its volume is not fixed.

In a review of eye-drop bottles, drop volume varied from bottle to bottle between 25 and 70 microliters; the dropper tip, the nature of the liquid and how the bottle is held affect drop size. The calculations on this site assume 1 drop is about 0.05 ml (1 ml ≈ 20 drops). For more accurate measurement, use an oral syringe marked in ml; parents measuring children’s medicine made far fewer errors with a syringe than with a dosing cup.

Source: Van Santvliet 2004, PMID 14998692, Yin 2016, PMID 27621414

Sublingual use

Placing drops under the tongue and holding them there for a while. The aim is for CBD to pass directly into the blood from inside the mouth.

In a small study in healthy men, there was no difference in blood CBD levels between sublingual drops and a swallowed capsule. According to the authors, the drops are most likely swallowed before they are absorbed in the mouth. In other words, holding it under the tongue has not been shown to clearly increase absorption.

Source: Johnson 2024, PMID 37733294

Related: Bioavailability, Drop

Endocannabinoid system

A system made up of cannabinoid-like substances the body produces itself, the receptors these substances bind to, and the enzymes that make and break them down.

It plays a role in many tissues, above all in the brain and nervous system. THC produces its effects by binding to this system’s cannabinoid receptors (the most common is CB1). A substance interacting with this system does not, on its own, show that it works for a disease; only clinical studies can show that.

Source: Lu 2016, PMID 26698193

Entourage effect

The idea that the compounds in cannabis work better together than on their own.

The term was introduced in 1998 in cell and mouse experiments with substances the body produces itself. It was later widely used in marketing “full-spectrum” products. Reviews say the evidence supporting it in humans is limited and that the concept should not be presented as a proven fact.

Source: Ben-Shabat 1998, PMID 9721036, Cogan 2020, PMID 32116073, Simei 2024, PMID 37535820

Related: Full-spectrum, Cannabinoid

Epidiolex (Epidyolex in Europe)

An approved (licensed) medicine made from purified CBD and taken by mouth. Each ml contains 100 mg of CBD.

It was approved in the US in 2018; it is used for seizures in Lennox-Gastaut syndrome, Dravet syndrome and tuberous sclerosis complex in people aged 1 year and older. It was licensed in Europe in 2019. Its effect was shown in double-blind, placebo-controlled studies; these results cannot be transferred to CBD oils whose contents and dose are unknown. For its status in Turkey, see our page on regulation in Turkey.

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, FDA 2018 (Epidiolex approval announcement), www.fda.gov, EMA 2026 (Epidyolex product page), www.ema.europa.eu, Miller 2020, PMID 32119035

Broad-spectrum

A type of product said to have had its THC removed while keeping the other cannabinoids.

One study found THC in some broad-spectrum products. In another study, CBG and CBDV, which the World Anti-Doping Agency (WADA) banned at the time, were detected in the urine of volunteers using a broad-spectrum product; CBDV was not listed on the product’s certificate of analysis. Athletes should check the current WADA list.

Source: Gidal 2024, PMID 38562466, Gillham 2026, PMID 40920736

Drug interaction

When two substances used together change each other’s effect or blood level.

CBD can raise the blood level of some medicines. For example, it raises the active by-product of the epilepsy medicine clobazam about 3 times; raised liver enzymes are seen more often when it is used with valproate. Tell your doctor and pharmacist about all the medicines you take.

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov

Isolate

Purified CBD on its own. It is expected to contain no other cannabinoids.

The provisional safe level in Europe’s food safety assessment was calculated only for CBD that is at least 98% pure. The approved CBD medicine also contains purified CBD. Not all products labeled “isolate” matched the definition either: in one study, 57% did.

Source: EFSA 2026, PMID 41668771, FDA 2018 (Epidiolex approval announcement), www.fda.gov, Gidal 2024, PMID 38562466

Level of evidence

A rating that shows how reliable a result is.

The international GRADE system looks at study type, risk of bias, and the consistency and precision of the results together. On this site, the evidence for CBD alone is shown as “strong,” “moderate,” “weak,” “very weak” or “insufficient”; products containing THC are rated separately. Today, strong evidence exists only for the approved CBD medicine in some severe types of epilepsy.

Source: Guyatt 2008, PMID 18436948

Cannabinoid

A family of compounds found in the cannabis plant. CBD and THC are the best-known members of this family.

The plant contains many cannabinoids; CBG, CBN and THCV are some of them. CBD and THC are first present in the plant in an “acid” form (CBDA, THCA). Similar substances the body produces itself are called endocannabinoids.

Source: Hanuš 2016, PMID 27722705, ElSohly 2020, PMID 34676337, Lu 2016, PMID 26698193

Liver enzymes (ALT, AST)

ALT and AST, which are checked in blood tests, rise in the blood when liver cells are damaged.

These enzymes can rise with CBD. Liver tests are ordered before starting the approved CBD medicine and in the months that follow; the risk increases when it is used with valproate. In a placebo-controlled study in healthy adults, enzymes rose above 3 times the normal level in 5.6% of those taking CBD (0% in the placebo group).

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, Florian 2025, PMID 40622698, Watkins 2021, PMID 33022751

Hemp

The Cannabis sativa plant. In everyday language, “hemp” means varieties that are low in THC and grown for fiber, seed or CBD.

The “low THC” limit varies from country to country; for example, US law counts a plant with no more than 0.3% Δ9-THC by dry weight as “hemp.” For the rules in Turkey, see our page on regulation in Turkey.

Source: FDA 2024 (cannabis and CBD regulation Q&A), www.fda.gov

Hemp seed oil

A cooking oil made by pressing hemp seeds. It is not CBD oil.

According to the FDA, hemp seeds do not naturally contain CBD or THC; seed products may contain only trace amounts picked up during processing. In 20 seed oils sold in Turkey, CBD was at most about 0.02 mg per ml. A bottle labeled “hemp oil” may be seed oil; if it doesn’t say how many mg of CBD it contains, don’t count it as a CBD product.

Source: FDA 2024 (cannabis and CBD regulation Q&A), www.fda.gov, Kacargil 2026, PMID 41621128

Contaminant testing (heavy metals, pesticides, residual solvents)

Tests that measure whether a product contains harmful substances: heavy metals (lead, arsenic, cadmium, mercury), agricultural chemicals (pesticides) and residues of solvents used in manufacturing.

Hemp is a plant that can accumulate heavy metals from the soil. In the US, low levels of lead were found in 42% of edible CBD products. In Australia, solvent (ethanol or isopropanol) residues were above the accepted limit in 29% of unregulated products used by children with epilepsy; in one sample, pesticide was 4.9 times the limit.

Source: Gardener 2022, PMID 35987236, Suraev 2022, PMID 34954507, Gidal 2024, PMID 38562466

Meta-analysis (and systematic review)

A systematic review finds and assesses all suitable studies on a topic using set rules. A meta-analysis combines the results of these studies statistically to calculate a pooled result.

A meta-analysis is only as good as the studies it includes: combining small studies with a high risk of bias does not produce strong evidence.

Source: Guyatt 2008, PMID 18436948

mg/kg (and mg/kg/day)

The amount in milligrams given for each kilogram of body weight. mg/kg/day describes the total amount taken in one day.

In research and for the approved CBD medicine, the dose is often written in mg/kg/day; studies used doses from below 1 up to 50 mg/kg/day. The mg/kg values on this site are doses used in studies, not personal dose recommendations. For food supplements, Europe’s provisional safe level is 0.0275 mg/kg/day (about 2 mg/day for a 70 kg adult).

Source: Millar 2019, PMID 31222854, FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, EFSA 2026, PMID 41668771

mg/ml (and percentage)

Shows how many milligrams of a substance are in 1 milliliter of liquid. Example: if a 10 ml bottle contains a total of 1000 mg of CBD, the product is 100 mg/ml.

The approved CBD medicine is 100 mg/ml. Some bottles show a percentage; 10% means about 100 mg in 1 ml. If the label only says “1000 mg per bottle,” check whether that is CBD or “hemp extract.”

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, Miller 2022, PMID 34998268

Novel food

A category used in the European Union for foods that count as new and must pass a safety assessment before they can be sold (Regulation (EU) 2015/2283).

The European Commission considers CBD a novel food. The European Food Safety Authority (EFSA) said in 2022 that its safety could not be established; in 2026 it announced a provisional safe level of 0.0275 mg/kg/day (about 2 mg/day at 70 kg) for supplements containing CBD that is at least 98% pure. In September 2026, it found a synthetic CBD application safe at no more than 2 mg a day for adults over 25 who are not pregnant or breastfeeding and who do not take medicines. These values are for food supplements; they are not medicine doses.

Source: EFSA 2022, PMID 35686177, EFSA 2026, PMID 41668771, EFSA 2026 (synthetic CBD opinion), PMID 42761670

Batch (lot) number

The number given to a group of products made in the same production run from the same raw material. It is printed on the bottle and on the certificate of analysis.

Because the contents can vary from batch to batch, the certificate of analysis should belong to the batch number of the bottle in your hand. In studies, CBD amounts differed between batches of the same product, and even between gummies in the same box.

Source: Miller 2022, PMID 34998268, Johnson 2025, PMID 40454463

Placebo

A product that looks like the real medicine but contains no active ingredient.

People who take a placebo can also improve noticeably. For example, in a CBD study in Dravet syndrome, seizures also fell by 27% in the placebo group (46–49% in the CBD groups). That is why improvement seen in studies without a comparison group cannot, on its own, be counted as the effect of the treatment.

Source: Miller 2020, PMID 32119035

Randomized controlled trial (RCT)

A study in which participants are assigned to groups by chance: one group receives the treatment being tested, the other receives a placebo or another treatment.

Assignment by chance makes the groups similar to each other, so a difference in the results most likely comes from the treatment. In a “double-blind” trial, neither the participants nor the researchers know who is in which group. It is the single most reliable type of study for showing whether a treatment works.

Source: Guyatt 2008, PMID 18436948

Prescription medicine vs. supplement

A prescription medicine’s effect and safety have been shown in clinical studies; its contents are standardized and its manufacturing is inspected. A dietary supplement, on the other hand, is not a product approved to treat disease.

With the approved CBD medicine, the amount in each ml is known; its label lists the dose, side effects and liver test monitoring. In supplements and unregulated products, the contents often don’t match the label. In the US, the FDA concluded that CBD does not fit the definition of a dietary supplement; in Europe, the provisional safe level for CBD in supplements is about 2 mg a day. For the rules in Turkey, see our page on regulation in Turkey.

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, FDA 2024 (cannabis and CBD regulation Q&A), www.fda.gov, EFSA 2026, PMID 41668771, Bonn-Miller 2017, PMID 29114823

Full-spectrum

A type of product said to contain hemp extract with other cannabinoids and a small amount of THC alongside CBD.

This is a marketing term; no binding official definition was found in the sources reviewed. In a study of 202 products, about a third of the 149 products that stated their type on the label did not match that type (full-spectrum, broad-spectrum, isolate). Because full-spectrum products contain THC, they carry a risk of a positive drug test.

Source: Gidal 2024, PMID 38562466, Sholler 2022, PMID 34089060

Carrier oil (MCT oil, etc.)

The oil that CBD is dissolved in. Examples: MCT (medium-chain triglyceride) oil, olive oil, sesame oil.

Having the carrier oil listed on the label matters for allergies: the approved CBD medicine contains sesame oil and is not used in people who are hypersensitive to sesame. When taken with food, especially fatty food, more CBD reaches the blood. The synthetic CBD that EFSA assessed in 2026 was also designed to be used in MCT oil.

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, Jang 2024, PMID 38850302, EFSA 2026 (synthetic CBD opinion), PMID 42761670

Tincture

Strictly speaking, a liquid plant extract made with alcohol. In the CBD market, oil-based CBD products in dropper bottles are also called tinctures.

Whatever it is called, what matters is that the label says how many mg of CBD are in 1 ml and what the base is (oil or alcohol). Of 18 tinctures bought online in the US, 12 had CBD amounts that differed from the label by more than 10%.

Source: Sullivan 2025, PMID 40518984

Titration (increasing step by step)

Starting a medicine at a low dose and increasing the dose step by step, guided by the response and side effects.

With the approved CBD medicine, the dose starts low based on body weight and is raised to the maintenance dose after one week; if needed, it is later increased step by step again. In a protocol for chronic pain based on expert opinion, CBD was increased in small steps every 2–3 days; this is expert opinion only. Your doctor decides how much and how fast to increase it.

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, Bhaskar 2021, PMID 34215346

Side effect

An unwanted effect of a medicine or substance.

In studies of the approved CBD medicine, the most common were sleepiness, decreased appetite, diarrhea and raised liver enzymes. In a 4-week study in healthy adults, liver enzymes also rose in some people. If you notice a new symptom, tell your doctor.

Source: FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov, Florian 2025, PMID 40622698

Half-life

The time it takes for the amount of a medicine in the blood to fall by half.

With the approved CBD medicine taken regularly twice a day, the terminal half-life is about 56–61 hours; the “effective” half-life, which matters for daily use, is 10–17 hours. With regular use, the blood level reaches a steady state in about 2–4 days.

Source: Taylor 2018, PMID 30374683, FDA 2026 (Epidiolex label, revision 05/2026), dailymed.nlm.nih.gov