How long does CBD stay in your system? What the science says

A common question about CBD is how long it stays in the body. There is no single answer: it depends on the route of administration, the dose, how often it is used and individual factors such as each person’s metabolism. This article explains what science knows about the pharmacokinetics of CBD —how it is absorbed, distributed, metabolised and eliminated— and what that means in terms of detection.

CBD pharmacokinetics: its journey through the body

When CBD enters the body, it goes through four phases that pharmacology calls ADME: absorption, distribution, metabolism and excretion. Each phase has its own variables and determines how long CBD remains active and for how long it can be detected.

Absorption: This depends on the route of administration. When inhaled, CBD enters the bloodstream within minutes. Sublingually, in 15-45 minutes. Orally, it can take 1 to 2 hours. Bioavailability ranges from 6% to 45% depending on the route.

Distribution: CBD is highly lipophilic and is widely distributed throughout the body’s tissues, with a particular affinity for adipose (fat) tissue. This property is key to understanding why it remains detectable for some time: CBD builds up in body fat and is released gradually.

Metabolism: CBD is metabolised mainly in the liver by cytochrome P450 enzymes, especially CYP2C19 and CYP3A4. The main metabolites are 7-OH-CBD and 7-COOH-CBD. The rate of metabolism varies between individuals according to their cytochrome P450 genetic profile.

Excretion: CBD metabolites are eliminated mainly in faeces (more than 60%) and to a lesser extent via the kidneys (in urine). Unmetabolised CBD barely appears in urine at all.

CBD half-life: how long it takes to be eliminated

The half-life of CBD —the time it takes for its concentration to fall by half— varies between studies. After a single use, it is estimated at between 18 and 32 hours. With chronic use, accumulation in fat tissue can extend this figure.

A study by Ohlsson et al. (1986) observed a half-life of 24 to 48 hours after single doses. More recent studies have found similar values. This means that after a single dose, CBD levels drop by half in roughly a day, and it may be practically eliminated within 3-5 days.

In frequent or chronic users, accumulation in fat tissue makes elimination slower. Metabolites may be detectable in urine for longer, similar to what happens with THC in regular users.

How long CBD lasts depending on the route

Inhalation: Inhaled CBD has the fastest onset (minutes) but also the shortest duration (2-4 hours of active effects). However, metabolites can remain detectable for days.

Sublingual (oil): Onset after 15-45 minutes, effects lasting 4-6 hours. Complete elimination within 3-5 days with occasional use.

Oral (capsules, edibles): Slower onset (1-2 hours), somewhat longer duration (6-8 hours) due to more gradual absorption. Elimination similar to the sublingual route.

*Please remember that the permitted use of CBD products in Spain and other European countries is topical use.

CBD detection in drug tests

Standard drug tests —those used in roadside checks, by employers or in sport— do not detect CBD. These tests look for THC (delta-9-tetrahydrocannabinol) and its main metabolite, 11-nor-9-carboxy-THC (THC-COOH).

There is, however, an important consideration: full-spectrum CBD products contain traces of THC within the legal limit (below 0.2%). With very frequent use of large amounts, these traces could build up to levels detectable by highly sensitive tests. With moderate use and certified quality products with THC below the legal threshold, the risk of testing positive is minimal but not zero.

CBD isolate or THC-free broad-spectrum products eliminate this risk, although anyone subject to regular testing should weigh this up carefully.

Individual factors that affect elimination

Body fat percentage matters: CBD accumulates in fat tissue. The higher the proportion of body fat, the slower total elimination may be. Liver metabolism varies genetically: fast metabolisers eliminate CBD more quickly than slow ones. Hydration and physical activity may also influence how quickly the metabolites are excreted through the kidneys.

Scientific sources and references

• Ohlsson, A. et al. (1986). “Single-dose kinetics of deuterium-labelled cannabidiol in man after smoking and intravenous administration.” Biomedical and Environmental Mass Spectrometry, 13(2), 77–83.
• Millar, S.A. et al. (2019). “A systematic review on the pharmacokinetics of cannabidiol in humans.” Frontiers in Pharmacology, 10, 1365.
• Grotenhermen, F. (2003). “Pharmacokinetics and pharmacodynamics of cannabinoids.” Clinical Pharmacokinetics, 42(4), 327–360.
• Huestis, M.A. et al. (2019). “Cannabidiol Adverse Effects and Toxicity.” Current Neuropharmacology, 17(10), 974–989.