Adults only (18+)

Immediate Effects on the Body and Brain

When cannabis is smoked or vaped, THC enters the lungs and quickly passes into the bloodstream, reaching the brain and other organs within minutes. If ingested orally, the effects are slower to begin, typically manifesting after thirty minutes to an hour. Users may experience an onset of euphoria, heightened sensory perception, relaxation and sometimes increased appetite, often referred to as the munchies. However, cannabis can also cause unwanted effects such as dry mouth, dizziness, red eyes, impaired coordination, altered time perception and memory difficulties. THC can also induce anxiety or paranoia, particularly in inexperienced users or when consuming high-potency cannabis.

Mental and Cognitive Effects

Acute intoxication with cannabis can impair attention, learning, verbal fluency, time estimation and memory functions such as short-term recall. It may also increase disinhibition and reduce psychomotor performance. Effects on working memory and executive function can vary between individuals and depend on dosage and THC concentration. In the longer term, especially when use begins in adolescence and continues regularly, studies link cannabis use with persistent deficits in cognitive function, including lower IQ, although causality remains debated.

Physical Health Risks

Smoking cannabis can irritate the airways, causing coughing, wheezing and exacerbation of asthma symptoms. It may also contribute to lung inflammation and chronic bronchitis. Some evidence suggests long-term inhalation may carry risks similar to tobacco smoking, including pre-cancerous changes, though findings are mixed. Cannabis use acutely raises heart rate and can affect blood pressure, posing greater risks for individuals with existing cardiovascular conditions. Rare but serious events such as heart attack or stroke have been reported. Heavy cannabis use has also been associated with reduced male fertility and epigenetic changes in sperm, as well as adverse developmental effects if used during pregnancy.

Dependence, Tolerance and Withdrawal

Around nine per cent of people who experiment with cannabis may develop cannabis use disorder. This rate increases to ten to twenty per cent among daily users. Daily consumers may develop tolerance, needing increasing amounts to achieve similar effects, and may experience withdrawal symptoms on cessation. Common symptoms include irritability, anxiety, sleep disturbance, low appetite and mood changes. Withdrawal typically starts within a week of quitting and resolves over several weeks.

Mental Health and Psychological Risks

There is clear evidence linking long-term cannabis use, especially of high-THC products, to increased risk of psychosis or schizophrenia, particularly in people with genetic or environmental vulnerabilities. The risk appears dose-dependent, with daily use conferring a significantly higher likelihood of psychotic symptoms. Cannabis may also exacerbate existing anxiety and depressive disorders.

Paradoxical Effects: Nausea and Appetite

While cannabis can ease nausea and stimulate appetite, in some frequent users it paradoxically triggers cannabinoid hyperemesis syndrome. This condition causes severe cyclical vomiting, abdominal pain and compulsive hot bathing for relief. It typically affects long-term frequent users and may lead to dehydration and kidney issues if not addressed.

Therapeutic Effects Under Medical Use

Cannabinoids such as THC and CBD are used therapeutically to relieve chronic pain, reduce chemotherapy-related nausea, ease muscle spasticity and treat certain forms of epilepsy. Evidence also suggests a reduction in opioid use among some patients using cannabis for pain relief. These benefits apply when cannabis-based medicines are prescribed under medical supervision in controlled settings.

Risks to Driving, Safety and Other Behaviours

Cannabis impairs motor coordination, reaction time and judgment. Driving under the influence of cannabis roughly doubles the risk of vehicle collision, particularly within three hours after consumption. Impaired users may misjudge time, distance and speed, increasing accident risk even if they feel capable.

Summary

Cannabis affects the body and mind through multiple systems. Short-term effects typically include euphoria, relaxation, altered perception, increased appetite and impaired coordination. Physical health risks include breathing problems, cardiovascular strain and potential reproductive issues. Long-term use, especially starting in adolescence or at high potency, can lead to cognitive deficits, dependence and mental health problems such as psychosis or depression. Paradoxical conditions such as cannabinoid hyperemesis syndrome can arise in chronic users. Medical use under medical supervision may yield benefits for certain conditions but still carries risks if misused. Understanding these effects and using care, especially when consumption is frequent or potent, is important for anyone considering or using cannabis.