THC (Δ⁹-tetrahydrocannabinol) is the principal cannabinoid of the cannabis plant and accounts for most of its psychoactive effect. It acts as a partial agonist at CB₁ and CB₂ receptors.

How long is THC detectable in the body?

In blood, active THC is detectable for hours to a few days; the metabolite THC-COOH persists in urine for roughly 1–3 days after occasional use and for several weeks in chronic users.

What is the difference between THC and CBD?

THC is psychoactive (CB₁ partial agonist); CBD is non-intoxicating and acts partly as an indirect modulator that can blunt some THC effects. Both are cannabinoids of the same plant.

Is THC legal in Germany?

Since 1 April 2024 (CanG) adults may possess up to 25 g in public / 50 g private and grow up to 3 flowering plants. Sale outside pharmacies and cultivation associations remains illegal.

THC (Tetrahydrocannabinol)

Δ⁹-Tetrahydrocannabinol (THC) is the most prominent of more than 100 cannabinoids identified in the cannabis plant and responsible for most of its psychoactive effect. It was isolated in 1964 by Raphael Mechoulam and Yechiel Gaoni at the Weizmann Institute — the birth of modern cannabinoid research.

Mechanism of action

THC acts as a partial agonist of the endocannabinoid system (ECS), mainly at two G-protein-coupled receptors:

CB₁ receptors: dense in the central nervous system (hippocampus, basal ganglia, cerebellum, cortex). Activation explains the psychoactive effects — altered perception, euphoria, impaired short-term memory, slowed time sense.
CB₂ receptors: mainly on immune cells and peripheral tissue; mediates immunomodulatory effects.

In the plant, THC exists mostly as non-psychoactive THC acid (THCA); only heat (smoking, vaping, baking) decarboxylates THCA into active THC.

Pharmacokinetics

Route	Onset	Peak	Duration
Inhalation	1–10 min	15–30 min	2–4 h
Oral (edibles)	30–120 min	2–4 h	4–10 h

Orally ingested THC is metabolised in the liver to 11-hydroxy-THC — a metabolite that is more potent and longer-lasting than THC itself, which explains the frequently underestimated strength of edibles.

Effects

Acute: relaxation, euphoria, altered sensory perception, increased appetite, dry mouth, bloodshot eyes. Adverse: tachycardia, dizziness, anxiety or paranoia — dose-dependent.

Chronic/risks: psychological dependence (~9–10 % of users), cannabis-induced psychosis in predisposed individuals, cannabinoid hyperemesis syndrome (CHS) in long-term heavy use, and impaired cognitive development with early onset.

Medical use

Cannabis has been prescribable in Germany since 2017. Established indications: chronic pain, spasticity in multiple sclerosis, chemotherapy-induced nausea, appetite loss. Dronabinol and nabiximols (Sativex) are approved finished medicines; flower and extracts are dispensed as pharmacy compounds.

Legal status 2026 (Germany)

The Cannabis Act (CanG, effective 1 April 2024) removed THC-containing cannabis from the Narcotics Act. Key rules for adults (18+): 25 g public / 50 g private possession, up to 3 flowering plants, distribution only via cultivation associations (max. 50 g/month for members), and a 3.5 ng/ml blood-serum THC driving limit since August 2024. The CDU/CSU–SPD government agreed to evaluate the law; as of November 2026 no full rollback has been enacted.

Note: This article is for general information only and is not medical advice. Consult a physician before using cannabis therapeutically.