Cannabis (drug)

• 1. Introduction

  ›

  Cannabis is one of the 483 known compounds bundled inside a single plant, and the one that matters most to its users is a molecule called tetrahydrocannabinol, or THC. The plant grows wild in the soil of Central or South Asia. People have called the drug it yields marijuana, weed, pot, Mary Jane, and ganja, among other names. In 2013, somewhere between 128 and 232 million people used it, which works out to between 2.7% and 4.9% of everyone on earth aged 15 to 65. That makes it the most commonly used largely-illegal drug in the world. Yet the questions surrounding it stay stubbornly open. Why has its potency climbed since the 1970s while its calming companion compound faded away? How did a substance burned at funerals 2,500 years ago end up reclassified by governments in our own decade? And why, after centuries of restriction beginning in the 14th century, did one small South American nation decide to make it fully legal?

• 2. The High And Its Aftermath

  ›

  Within minutes of smoking cannabis, a euphoriant effect can take hold. The user may feel relaxation, an altered sense of time and space, increased appetite, and a heightened awareness of sensation. Onset takes longer when the drug is eaten, sometimes up to 90 minutes, because orally consumed drugs must first be digested and absorbed. The effects last two to six hours depending on the amount used. Increased heart rate, impaired short-term and working memory, and poor psychomotor coordination round out the common physical signature.

  At high doses the experience can curdle. Mental effects can include anxiety, delusions, hallucinations, panic, paranoia, and psychosis. Some users may experience an episode of acute psychosis that usually abates after six hours, though in rare instances heavy users find the symptoms continuing for many days. There is a strong relation between cannabis use and the risk of psychosis, but the direction of causality is debated.

  Driving is where the impairment turns dangerous to others. THC was the illicit drug most frequently found in the blood of drivers involved in vehicle crashes. Those with THC in their system are from three to seven times more likely to be the cause of a crash than people who used neither cannabis nor alcohol. Legalization has also increased the rate at which children are exposed, particularly through edibles, where they risk encephalopathy, respiratory depression severe enough to require ventilation, and coma.

• 3. Sacred Smoke

  ›

  The Hindu god Shiva is described as a cannabis user, known as the "Lord of bhang." That sacred status reaches deep into the past of the Indian subcontinent, where the plant has served as an entheogen since the Vedic period. The earliest reports of its holiness come from the Atharva Veda, estimated to have been composed around 1400 BCE.

  The ancient Greeks may have first learned of cannabis by watching Scythian funerals, during which the drug was consumed. The word itself carries that lineage. In Akkadian it was known as qunubu, adopted into Hebrew as qaneh bosem. The Greek term passed into Latin and evolved through Proto-Germanic into Old Norse hampr, Old English hænep, and ultimately the modern English word "hemp."

  In modern culture, the spiritual use of cannabis has been spread by disciples of the Rastafari movement, who treat it as a sacrament and as an aid to meditation. The thread of religious use runs through Islam as well, where Muslims in various Sufi orders used cannabis as early as the Mamluk period, among them the wandering ascetics known as the Qalandars.

• 4. A Plant Many Ways

  ›

  Marijuana, the dried flowers, fruits, leaves, and stems of the female cannabis plant, is the most widely consumed form and the stock from which all others are derived. It contains 3% to 20% THC, with reports of up to 33%. Nearly every preparation hinges on heat, which decarboxylates the acid THCA into active THC. Raw leaf is not psychoactive, because its cannabinoids remain locked in the form of carboxylic acids.

  Kief, a powder rich in trichomes, can be sifted from cannabis and either used as is or pressed into hashish. The word derives from colloquial Arabic meaning pleasure. Hashish itself is a concentrated resin cake produced from pressed kief, varying in color from black to golden brown depending on purity and cultivar.

  Hash oil sits at the potent end of the spectrum, a resinous matrix of cannabinoids drawn out by solvent extraction. Butane and supercritical carbon dioxide versions have grown popular in recent years. The United Nations Office on Drugs and Crime notes that cannabis flower often contains 5% THC, resin can contain up to 20%, and oil may exceed 60% THC content.

  Not every preparation is benign by design. Marihuana prensada, or pressed marijuana, spread among the lower classes of South America, especially in the 1990s. Known as paraguayo for its main producer Paraguay, it is dried and mixed with binding agents that make it toxic, then cut into bricks called ladrillos and sold cheaply across Argentina, Brazil, Chile, Peru, Venezuela, and the United States.

• 5. The Potency Problem

  ›

  Since the 1970s the potency of illicit cannabis has greatly increased, with THC levels rising and CBD levels dropping. Part of that shift traces to where the plant is now grown. More illegal growers cultivate indoors under artificial lights to avoid detection, which reduces the plant's CBD production. The trade-off matters, because CBD is not just a passenger compound.

  THC is a weak partial agonist at the CB1 receptor, while CBD acts as a CB1 receptor antagonist. A 2015 review found that high CBD-to-THC strains showed significantly fewer positive symptoms such as delusions and hallucinations, better cognitive function, lower risk of developing psychosis, and a later age of onset for the illness compared to low CBD-to-THC strains. Stripping out CBD, in other words, may remove a natural brake.

  The high lipid-solubility of cannabinoids keeps them lingering in the body for long periods. Even after a single dose of THC, detectable levels can be found for weeks or longer. Investigators have suggested this matters because cannabinoids may accumulate in the lipid membranes of neurons. That persistence is precisely what forensic testing exploits, measuring THC and its metabolite THC-COOH in blood, urine, hair, oral fluid, or sweat.

• 6. What The Body Pays

  ›

  About 9% of those who experiment with marijuana eventually become dependent under DSM-IV criteria, compared to 20% for cocaine, 23% for alcohol, and 68% for nicotine. Among daily users, roughly 50% experience withdrawal upon stopping, marked by sleep problems, irritability, dysphoria, and craving. That withdrawal is less severe than withdrawal from alcohol.

  Cannabinoid hyperemesis syndrome strikes some chronic users with repeated bouts of uncontrollable vomiting lasting 24 to 48 hours. Four deaths have been reported as a result of it. The lungs carry their own burden, since cannabis smoke contains thousands of compounds and over fifty known carcinogens, including nitrosamines, reactive aldehydes, and benzapyrene. Cannabis smoke is also inhaled more deeply than tobacco smoke.

  The heart appears to suffer too. A systematic meta-analysis showed cannabis users double their chance of dying from heart disease, with a 29% higher risk of heart attack and a 20% higher risk of stroke than non-users. Smoking it has been shown to raise the risk of myocardial infarction by 4.8 times in the 60 minutes after consumption.

  The heaviest toll falls on those who cannot stop. A 2025 study found that individuals diagnosed with cannabis use disorder face a nearly threefold increase in mortality over a five-year period, and are ten times more likely to die by suicide than the general population.

• 7. Centuries Of Restriction

  ›

  Cannabis was introduced to the New World by the Spaniards in 1530 to 1545, but its troubles with the law began far earlier, with criminalization in some countries starting in the 14th century. The colonial government of Mauritius banned it in 1840 over concerns about its effect on Indian indentured workers, and Singapore followed in 1870. In the United States, the first restrictions on sale arrived in 1906 in the District of Columbia.

  The Western fascination with the drug had a literary and medical flowering in the 19th century. French physician Jacques-Joseph Moreau wrote on its psychological effects and founded the Paris Club des Hashischins in 1844. Irish physician William Brooke O'Shaughnessy, who studied it as a medical officer in Bengal with the East India Company, carried a quantity back to Britain in 1842. Charles Baudelaire's Les paradis artificiels in 1860 and Fitz Hugh Ludlow's The Hasheesh Eater in 1857 captured the period's curiosity.

  Prohibition hardened in the 20th century. In 1925, an international conference in Geneva produced a compromise banning the export of "Indian hemp" to countries that had prohibited its use. In the United States in 1937, the Marihuana Tax Act prohibited the production of hemp alongside cannabis. Canada had already criminalized the drug in The Opium and Narcotic Drug Act of 1923, before any reports of its use in Canada even existed.

• 8. The Turn Toward Legality

  ›

  In December 2013, Uruguayan President Jose Mujica signed legislation legalizing recreational cannabis, making Uruguay the first country in the modern era to do so. The following August, Uruguay went further, allowing people to grow up to six plants at home and to form growing clubs, alongside a state-controlled dispensary regime. Retail came slowly. After a long delay, sixteen pharmacies were finally authorized to sell it commercially in 2017.

  The United States moved state by state. Washington became the first to legalize recreational cannabis in state law through Washington Initiative 502 in December 2012, with Colorado following close behind via Colorado Amendment 64. As of the source, 24 states, 3 territories, and the District of Columbia have legalized recreational use, though the drug remains illegal at the federal level. After legalization, street prices fell. In Colorado, smokable buds dropped 40 percent between 2014 and 2019, from $200 per ounce to $120.

  The roster of legalizing nations grew to include Canada, Georgia, Germany, Luxembourg, Malta, South Africa, and Thailand. Canada became the second country to fully legalize recreational use on the 17th of October 2018, and the first G7 nation to do so. Malta in 2021 was the first European Union member to legalize recreational use.

  Federal posture in the United States has begun to shift as well. On the 30th of April 2024, the Department of Justice announced it would move to reclassify cannabis from a Schedule I to a Schedule III controlled substance, and on the 18th of December 2025, an executive order was signed to make that reclassification real.