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Cannabis Facts

Cannabinoid; Cannabinoid; Cannabinoid CB1 receptor partial agonist

Description

Cannabis (Cannabis sativa L., Cannabaceae) — weed, pot, marijuana — is a flowering plant whose resinous preparations are among the most widely consumed psychoactive substances on earth.[1] Its primary psychoactive constituent, tetrahydrocannabinol (tetrahydrocannabinol), is chemically distinct from classical opioids or serotonergic psychedelics. THC activates the brain's endocannabinoid system, disrupting normal signaling across memory, reward, and sensory processing circuits.[2]

Subjective effects include euphoria, heightened sensory perception, appetite stimulation, altered time perception, and relaxation.[3] Smoked preparations act within minutes and last one to three hours; edibles take 30–90 minutes to peak and can last four to eight hours, with a more sedating and body-prominent character.

Cannabis use disorder develops in approximately 9% of users, though no human fatality from cannabis alone has been documented.[4] The main ongoing risks are psychological dependence with a recognised withdrawal,[5] cyclic vomiting in heavy users,[6] and dose-dependent psychosis risk that increases with high-potency preparations.[7]

Dose and durationby route · individual sensitivity varies

Oral(mg THC)
Threshold< 2.5 mg THCLight2.5 – 5 mg THCCommon5 – 15 mg THCStrong15 – 30 mg THCHeavy50+ mg THC

Starts in 30 – 120 minLasts 4 – 8 hoursAfter-effects 2 – 6 hours

Body and dependence

Acute toxicity
Low
Chronic toxicity
Moderate
Physical dependence
Moderate
Psychological dependence
Moderate
Withdrawal
Moderate
Compulsive redosing
Low

Tolerance

Builds
Moderate
Fully resets after
17.5 days
Carries over to
Synthetic cannabinoids; Other plant-derived CB1 agonists

Effectslikely at a common dose

Perception
Music enhancement; +18 possible, including Vestibular distortion, Visual acuity suppression, Spatial disorientation
Body
Dry mouth; Body high; Heart rate perception changes; +20 possible, including Motor control impairment, Abnormal heartbeat, Dizziness
Thinking
Cognitive euphoria; Memory suppression; +29 possible, including Cognitive impairment, Decision impairment, Analysis suppression
Feeling
Euphoria; +7 possible, including Anxiety, Paranoia, Emotional lability
Self
none likely · 8 possible, including Craving
Time
Time alteration; +2 possible, including Temporal disorientation
Awareness
none likely · 2 possible

Who shouldn't take it

Absolute
Pregnancy
Relative
Significant cardiovascular disease; Respiratory disease (smoked preparations); Personal or family history of psychotic disorders; Hepatic impairment; Adolescence (under 25); Concurrent CYP2C9 substrates (e.g., warfarin); Concurrent CYP3A4 substrates (e.g., midazolam); Concurrent CNS depressants (opioids, benzodiazepines, alcohol)

Combinations60 recorded

Dangerous (11)
Ketamine, DXM, PCP; Opioids; GHB, Baclofen; GHB, GBL; Ibogaine; Local anesthetics; MAOIs; NDRIs (Wellbutrin); Salvia, Ibogaine; SNRIs; Synthetic cannabinoids
Caution (33)
See full page: psychedex.org/substances/cannabis
Not graded (16)
Not listed never means safe.

Seek help immediately if

Natural cannabis rarely causes a medical emergency — "greening out" is: pale/sweaty skin, dizziness, nausea or vomiting, anxiety or panic, rapid heartbeat, feeling faint — and usually passes with rest.

Seek emergency help for these — far more likely with synthetic cannabinoids ("spice" / K2):

  • Seizures
  • Severe chest pain; very fast or irregular heartbeat
  • Unresponsiveness or extreme drowsiness
  • Severe agitation, aggression, or psychosis
  • Repeated vomiting; difficulty breathing

What to do

  1. Sit or lie them down somewhere calm, cool, and quiet
  2. Reassure them — cannabis panic and "greening out" pass with time
  3. Offer sips of water; a little sugar can help if they feel faint
  4. Recovery position if nauseated, drowsy, or vomiting
  5. Stay with them and monitor
  6. For seizures, chest pain, unresponsiveness, or severe agitation, call emergency services

Natural cannabis "greening out" resolves with rest, calm, and time, with no lasting harm. Synthetic cannabinoids are unpredictable and can cause seizures, cardiac events, kidney injury, and severe agitation that needs emergency care.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

Version r2 · Not medical advice

References

  1. [1]
    ^Andre CM, Hausman JF, Guerriero G (2016) Cannabis sativa: The Plant of the Thousand and One Molecules — Frontiers in Plant Science doi:10.3389/fpls.2016.00019
  2. [2]
    ^Hempel B, Xi ZX (2022) Receptor mechanisms underlying the CNS effects of cannabinoids: CB1 receptor and beyond — Advances in Pharmacology doi:10.1016/bs.apha.2021.10.006
  3. [3]
    ^Englund A, Oliver D, Chesney E, Chester L, Wilson J, Sovi S, De Micheli A, Hodsoll J, Fusar-Poli P, Strang J, Murray RM, Freeman TP, McGuire P (2023) Does cannabidiol make cannabis safer? A randomised, double-blind, cross-over trial of cannabis with four different CBD:THC ratios — Neuropsychopharmacology doi:10.1038/s41386-022-01478-z
  4. [4]
    ^Lachenmeier DW, Rehm J (2015) Comparative risk assessment of alcohol, tobacco, cannabis and other illicit drugs using the margin of exposure approach — Scientific Reports doi:10.1038/srep08126
  5. [5]
    ^Connor JP, Stjepanovic D, Budney AJ, Le Foll B, Hall WD (2022) Clinical management of cannabis withdrawal. — Addiction doi:10.1111/add.15743
  6. [6]
    ^Bonnet U (2025) Cannabinoid Hyperemesis Syndrome: A Scoping Review — Fortschritte der Neurologie-Psychiatrie doi:10.1055/a-2704-5465
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