Cannabis

Plant Medicine

Cannabis is a widely used plant whose main active compound, THC, produces relaxation, euphoria, and altered perception by acting on the body's endocannabinoid system. It is used recreationally, medicinally, and in some spiritual contexts, and — unlike the classic psychedelics — it can lead to dependence.

Also known as: Marijuana, Weed, Pot, Ganja, Hashish, THC, Cannabis sativa

Written by Psymerge Editorial Team · Last updated June 4, 2026

Key facts

CategoryPlant Medicine
OnsetSmoked: minutes; edibles: 30–120 minutes
PeakSmoked: around 30 minutes; edibles: 2–4 hours
Total durationSmoked: 2–4 hours; edibles: 4–8+ hours
After-effectsGrogginess or mental 'fog' the next day, especially with higher doses

Overview

Cannabis (from Cannabis sativa and related plants) contains a family of compounds called cannabinoids. The main intoxicating one is THC (delta-9-tetrahydrocannabinol), which activates CB1 receptors in the brain; another prominent cannabinoid, CBD, is not intoxicating and modulates some of THC's effects (Volkow et al., 2014). Cannabis is consumed by smoking, vaporising, or as edibles, oils, and tinctures.

Effects typically include relaxation, euphoria, altered perception, and increased appetite, but also — particularly at higher doses or in inexperienced users — anxiety and paranoia. Timing depends heavily on the route: smoking acts within minutes, while edibles come on slowly and last much longer, which makes accidental overconsumption common.

While often perceived as low-risk, cannabis is not harmless: it can cause dependence, is associated with an increased risk of psychosis in vulnerable people, and carries particular concerns for adolescents and during pregnancy (Volkow et al., 2014). This page summarises its pharmacology, effects, and risks, drawing on peer-reviewed literature and harm-reduction resources.

History & origins

Cannabis is one of the oldest cultivated plants, used for fibre, food, medicine, and ritual across Asia, the Middle East, and Africa for thousands of years. It features in traditional medicine systems and in some religious practices, and spread globally through trade and migration.

In the twentieth century most countries prohibited cannabis, but recent decades have seen widespread medical legalisation and, in a growing number of places, regulated adult recreational use. This shift has been accompanied by a marked rise in the potency of available products and by extensive scientific study of both its therapeutic potential and its harms (Volkow et al., 2014).

Pharmacology & how it works

Cannabis's intoxicating effects come mainly from THC (delta-9-tetrahydrocannabinol), which activates CB1 cannabinoid receptors that are part of the body's endocannabinoid system. CBD, another major cannabinoid, is not intoxicating and can modulate some of THC's effects (Volkow et al., 2014). The plant also contains many other cannabinoids and aromatic terpenes that may shape the overall experience.

Chemical class
Phytocannabinoid (THC / CBD)
Routes of administration
Smoked, Vaporised, Oral (edibles, oils, capsules), Sublingual (tinctures)
Tolerance
Tolerance builds with regular use, and heavy users can experience a withdrawal syndrome (irritability, poor sleep, reduced appetite) on stopping.

Pharmacokinetics

Smoked or vaporised cannabis acts within minutes and lasts a few hours. Edibles are absorbed through the gut, where THC is converted to a stronger, longer-lasting compound (11-hydroxy-THC); this delays onset to 30–120 minutes and extends effects to many hours, which is why dosing edibles is easy to get wrong.

Effects

Physical Effects

  • Increased heart rate
  • Dry mouth and reddened eyes
  • Increased appetite (the 'munchies')
  • Relaxation or, in some, restlessness
  • Impaired coordination and slower reaction time
  • Dizziness, especially when standing

Psychological Effects

  • Relaxation and euphoria
  • Altered perception of time and the senses
  • Heightened enjoyment of music, food, and activities
  • Talkativeness or introspection
  • Anxiety, paranoia, or panic, especially at higher doses or in inexperienced users
  • Impaired short-term memory and concentration

Spiritual Effects

  • An enhanced sense of connection or creativity for some people
  • Reflective or contemplative states
  • Use in some traditions as an aid to meditation or ritual

Dosage Information

Low: 1–2.5 mg THC (oral / edible)
Medium: 2.5–5 mg THC (oral / edible)
High: 5–15+ mg THC (oral / edible)

Doses here are for oral THC; an edible dose that seems small can be very strong because of delayed onset, so start low and wait. Smoked or vaporised potency varies enormously between products and strains. Educational only and not an endorsement of use.

Risks & safety

Contraindications

Cannabis is best avoided, or used only with caution, by:

  • People with a personal or family history of psychosis, schizophrenia, or bipolar disorder, for whom cannabis (especially high-potency THC) can trigger or worsen symptoms.
  • Adolescents, whose developing brains are more vulnerable to lasting effects.
  • People with cardiovascular conditions, because of the transient rise in heart rate and blood pressure.
  • Pregnant or breastfeeding people.
  • People with a history of cannabis or other substance use disorder.

Drug interactions

Cannabis can interact with other drugs and medications.

  • Alcohol and other depressants or sedatives: add to impairment, drowsiness, and the risk of 'greening out'.
  • Liver-metabolised medications: THC and especially CBD can affect liver enzymes (CYP450) and alter levels of some drugs, such as certain blood thinners and anti-seizure medicines.
  • Stimulants: may compound effects on heart rate.

Tell a clinician about cannabis use if you take regular medication.

Psychological distress & bad trips

Anxiety, paranoia, and panic are among the most common adverse reactions to cannabis, particularly with high-THC products, edibles taken in excess, or use by inexperienced people or in stressful settings. These episodes are usually temporary, but they can be frightening, and in vulnerable individuals cannabis can provoke transient psychotic symptoms.

Rare but serious risks

Although rarely life-threatening, cannabis carries several meaningful risks:

  • Psychosis: cannabis use — especially heavy use of high-potency products and use during adolescence — is associated with an increased risk of psychotic disorders, particularly in people with a predisposition (Volkow et al., 2014).
  • Dependence: a cannabis use disorder can develop (see below).
  • Cognitive effects: heavy use beginning in adolescence has been linked to lasting effects on memory and learning.
  • Cannabinoid hyperemesis syndrome: chronic heavy use can cause recurrent severe vomiting.
  • Respiratory harm from smoking, rare cardiovascular events, and a clear increase in motor-vehicle accident risk when driving impaired.

Vulnerable populations

Some groups face higher risk and should avoid or be especially cautious with cannabis:

  • Adolescents and young adults, whose brains are still developing.
  • People with a personal or family history of psychosis, schizophrenia, or bipolar disorder.
  • Pregnant or breastfeeding people.
  • People with heart conditions.
  • People with a history of substance use disorder.

Dependency & addiction potential

Unlike the classic psychedelics, cannabis can be addictive. Roughly 1 in 10 users develops a cannabis use disorder, and the risk is higher — around 1 in 6 — among those who start in adolescence (Volkow et al., 2014). Regular heavy users can experience withdrawal symptoms such as irritability, sleep difficulty, reduced appetite, and restlessness when they stop.

Overdose

Cannabis does not cause fatal overdose in the way opioids or depressants can, because the brain regions controlling breathing have few cannabinoid receptors. However, taking too much — 'greening out' — can cause intense anxiety, nausea and vomiting, paranoia, a racing heart, and fainting, and is a common result of edibles because of their delayed onset. Accidental ingestion by children is a medical emergency. Seek medical help for severe distress, chest pain, persistent vomiting, or if a child has consumed cannabis.

Harm Reduction

  • With edibles, start low (around 1–2.5 mg THC) and wait at least two hours before taking more — delayed onset is the main cause of accidental overconsumption.
  • Avoid mixing cannabis with alcohol or other depressants, which increases impairment and the chance of 'greening out'.
  • Do not drive or operate machinery while impaired.
  • Be cautious with high-potency products, especially if you are inexperienced or prone to anxiety.
  • Store cannabis securely away from children and pets; accidental ingestion is a medical emergency.
  • If you have a personal or family history of psychosis, schizophrenia, or bipolar disorder, avoid cannabis or be very cautious, particularly with high-THC products.
  • Vaporising or oral use avoids the respiratory harms of smoking.

Cultural & spiritual context

Cannabis occupies many cultural roles at once: a traditional medicine and ritual plant (for example in some South Asian and Rastafari practices), a mainstream recreational substance, and an increasingly mainstream medicinal product. Within plant-medicine and ceremonial contexts it is sometimes used as an aid to relaxation, meditation, or connection.

Its rapidly changing legal status and rising potency have shifted the cultural conversation toward questions of responsible use, youth protection, driving safety, and honest public-health messaging — moving past both blanket prohibition and the assumption that cannabis is entirely harmless.

Legal Status

Laws vary widely by country and change frequently, so we don't track legal status here to avoid showing outdated information.

Check current worldwide legal status on Psychedelic Alpha

Frequently asked questions

Why do edibles feel stronger and last longer than smoking?

When cannabis is eaten, THC is processed by the gut and liver into 11-hydroxy-THC, a more potent and longer-lasting compound. This is why edibles come on slowly (30–120 minutes) and last many hours, and why it is easy to take too much before the first dose is felt.

Can cannabis cause psychosis?

Cannabis use is associated with an increased risk of psychotic disorders, especially with heavy use of high-potency products, use during adolescence, and in people with a personal or family predisposition (Volkow et al., 2014). It does not affect everyone the same way, but the link is well documented.

Is cannabis addictive?

Yes. Unlike the classic psychedelics, cannabis can lead to a cannabis use disorder. About 1 in 10 users overall, and roughly 1 in 6 of those who start in adolescence, develop dependence, and heavy users can experience withdrawal when they stop (Volkow et al., 2014).

What does 'greening out' mean?

'Greening out' is the term for taking too much cannabis, producing intense anxiety, nausea and vomiting, paranoia, a racing heart, and sometimes fainting. It is unpleasant but generally not life-threatening; rest, reassurance, hydration, and a calm setting usually help.

Is cannabis safe during pregnancy?

No. Health authorities advise avoiding cannabis during pregnancy and breastfeeding, as cannabinoids cross to the developing baby and have been linked to potential effects on development.

Need Integration Support?

Connect with qualified integration guides who can help you process and integrate your experiences safely and effectively.

Find a Guide

Related substances

Ayahuasca

Plant Medicine

Ayahuasca is an Amazonian psychedelic brew that combines a DMT-containing plant with an MAO-inhibiting vine, making the DMT orally active. Used ceremonially for centuries, it produces a long, visionary, and often cathartic experience — typically including purging — lasting around 4–6 hours.

Kambo

Plant Medicine

Kambo is the dried skin secretion of the giant monkey frog (Phyllomedusa bicolor), applied to small fresh skin burns in an Amazonian purification practice. It is not a psychedelic: it triggers an intense, short-lived physical reaction — flushing, vomiting, and a racing heart — and carries real, documented risks.

Peyote

Plant Medicine

Peyote (Lophophora williamsii) is a small, slow-growing cactus of the Chihuahuan Desert whose principal psychoactive component is mescaline. Used ceremonially for thousands of years and central to the Native American Church, it produces a long, visionary experience and is now seriously threatened by over-harvesting.

Rapé

Plant Medicine

Rapé (pronounced ha-PEH) is an Amazonian shamanic snuff made mainly from potent tobacco, often blended with plant ashes, and blown forcefully into the nostrils. It is not a psychedelic: it produces a brief, intense, grounding rush followed by calm and focus, and — being tobacco-based — it contains nicotine.

References & further reading

  • Volkow, N. D., Baler, R. D., Compton, W. M., & Weiss, S. R. B. (2014). Adverse Health Effects of Marijuana Use. New England Journal of Medicine, 370(23), 2219–2227. https://doi.org/10.1056/NEJMra1402309
  • National Academies of Sciences, Engineering, and Medicine. (2017). The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington, DC: The National Academies Press. https://doi.org/10.17226/24625
  • Hall, W., & Degenhardt, L. (2009). Adverse health effects of non-medical cannabis use. The Lancet, 374(9698), 1383–1391. https://doi.org/10.1016/S0140-6736(09)61037-0
  • National Institute on Drug Abuse (NIDA). Cannabis (Marijuana). https://nida.nih.gov/research-topics/cannabis-marijuana
  • European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). Cannabis drug profile. https://www.emcdda.europa.eu/publications/drug-profiles/cannabis_en
  • Erowid. Cannabis Vault. https://www.erowid.org/plants/cannabis/
  • DanceSafe. https://dancesafe.org/drug-information/
  • TripSit. Drug combinations chart. https://wiki.tripsit.me/wiki/Drug_combinations

About this article

Written by:
PE
Psymerge Editorial Team
Last updated June 4, 2026