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The oldest known psychoactive substance, with evidence of intentional fermentation dates to approximately 7000 BCE in China. Rated as the most harmful substance overall in expert analyses that weigh both individual and societal damage. Involved in more drug interaction deaths than any other substance because it potentiates nearly every depressant.

Consumed for over a millennium. Coffee cultivation traces to 9th-century Ethiopia, tea to ancient China. The world's most widely consumed psychoactive substance, acting as an adenosine receptor antagonist. Physical dependence develops quickly, with withdrawal headaches beginning 12-24 hours after the last dose.

Tobacco has been used by indigenous peoples of the Americas for thousands of years in ceremonial and medicinal contexts. Activates the nicotinic acetylcholine receptor and is one of the most addictive substances known. About 32% of people who ever smoke become dependent in their lifetime, and around 50-67% of those who progress to daily smoking do (Anthony et al. 1994; Lopez-Quintero et al. 2011). Most of the harm comes from smoking specifically; nicotine alone (patches, gum, vaping) is far less harmful than combustion.

One of the oldest cultivated plants, with evidence of use dates to at least 3000 BCE in Central Asia. Acts on the endocannabinoid system (CB1/CB2 receptors), producing relaxation, altered perception, and appetite stimulation. Alcohol increases THC blood levels by approximately 60%, explaining why the combination hits harder than either alone.

Derived from coca leaves, which have been chewed in the Andes for at least 5,000 years; the alkaloid was first isolated in 1860. Blocks dopamine, serotonin, and norepinephrine reuptake. Combined with alcohol, the liver creates cocaethylene, a unique compound more cardiotoxic than either drug alone.

3,4-Methylenedioxymethamphetamine, first synthesized at Merck in 1912 as a pharmaceutical intermediate; its psychoactive properties went unnoticed until Alexander Shulgin resynthesized it in 1976. Works by reversing serotonin, dopamine, and norepinephrine transporters, and inactivates the liver enzyme (CYP2D6) that clears it, so redosing produces disproportionately higher blood levels. Serotonin depletion after use causes a characteristic low mood 2-4 days later.

First synthesized in 1887; marketed as Benzedrine inhalers in the 1930s and used extensively by all sides in World War II. Release dopamine and norepinephrine, with extended-release formulations lasting significantly longer than instant-release. Therapeutic doses are well-studied; cardiovascular risk scales with dose and frequency.

Used ceremonially in Mesoamerica for at least 2,000 years; the active compound was isolated by Albert Hofmann in 1958. Among the safest psychoactives known. No lethal dose has been established in humans. Whole mushrooms are almost never adulterated, and tea preparation produces a faster onset with shorter effects than eating them.

Lysergic acid diethylamide, first synthesized by Albert Hofmann at Sandoz Laboratories in 1938; its psychoactive properties were discovered accidentally in 1943. Extremely potent: active in microgram doses, far below what's visible to the eye. Rarely adulterated on blotter; NBOMe compounds are the main substitution risk and are bitter-tasting, unlike LSD.

Synthesized in 1962 at Parke-Davis as a safer alternative to PCP for anesthesia. FDA-approved for humans in 1970, it became the most widely used battlefield anesthetic in the Vietnam War - field medics could administer it without surgical equipment because, unlike opioids and earlier anesthetics, it preserves breathing and airway reflexes. The 'horse tranquilizer' label comes from its use in veterinary medicine, but it was developed for humans first and remains on the WHO's List of Essential Medicines for human surgery and emergency care. Blocks NMDA receptors, producing a dose-dependent spectrum from mild dissociation to complete K-hole immersion. Now FDA-approved as esketamine (Spravato) for treatment-resistant depression; tolerance builds quickly and chronic heavy use causes bladder damage.

Heroin was synthesized in 1874 and marketed by Bayer in 1898 as a non-addictive morphine substitute. Mu-opioid receptor agonist that produces profound pain relief and euphoria. In most US markets, samples sold as heroin now contain primarily fentanyl. Only ~2% test as expected heroin.

First crystallized by Japanese chemist Akira Ogata in 1919; used extensively by Axis and Allied militaries in WWII under brand names like Pervitin. Produces intense dopamine release that is directly neurotoxic (damaging to dopamine neurons themselves) at high doses. Street purity is typically high (~88%), meaning the danger is the drug itself, not adulterants.

The first benzodiazepine (chlordiazepoxide/Librium) was discovered accidentally by Leo Sternbach in 1955. GABA-A receptor modulators that are relatively safe alone but extremely dangerous combined with opioids, alcohol, or GHB. Physical dependence develops within 2-4 weeks of daily use, and withdrawal can cause seizures.

Synthesized in 1960 by Paul Janssen and originally used exclusively in surgical anesthesia. Approximately 50-100x more potent than morphine, with an active dose measured in micrograms. Now detected as a contaminant in cocaine, methamphetamine, pressed pills, and counterfeit prescriptions across most US drug markets.

Derived from the leaves of Mitragyna speciosa, used for centuries in Southeast Asia by laborers and in traditional medicine. A partial mu-opioid agonist, meaning it activates the same receptor as morphine but only partway, with a built-in ceiling. Its dose-dependent effects shift from stimulating (low doses) to sedating (high doses). Only 5% of kratom-positive overdose deaths had kratom as the sole substance; fatality risk increases when combined with other depressants.

Dextromethorphan, developed in the 1950s as a non-addictive replacement for codeine in cough suppressants. Effects are described in four dose-dependent plateaus, from mild stimulation to full dissociation. Many OTC formulations contain acetaminophen, guaifenesin, or antihistamines that are toxic at recreational DXM doses.

Gamma-hydroxybutyrate, synthesized in 1960 by French researcher Henri Laborit during research on GABA neurotransmission. One of the steepest dose-response curves of any recreational substance: the difference between a recreational dose and a fatal dose can be less than 2x. Combined with any other depressant, individually survivable doses become lethal.

Discovered by Joseph Priestley in 1772; recreational laughing gas parties were popular in the early 1800s before its medical applications were recognized. The fastest onset and offset of any recreational substance. Triggers release of your body's own endorphins in the brainstem, which is why mixing with taken opioids is dangerously additive. You stack their effect on top of a drug that's already activating the same system.

Amyl nitrite was first synthesized in 1844 and originally used medically for angina; recreational use became widespread in the 1970s. Inhaled alkyl nitrites that cause brief vasodilation, head rush, and smooth muscle relaxation. Combined with PDE5 inhibitors (Viagra/Cialis), both increase cyclic GMP, causing potentially fatal blood pressure collapse. This is an absolute pharmacological contraindication.

Developed in 1962 by the German pharmaceutical company Grünenthal. An atypical opioid that also inhibits serotonin and norepinephrine reuptake, creating interaction risks that pure opioids don't have. Lowers seizure threshold (seizures occur even at prescribed doses) and is uniquely dangerous with other serotonergic drugs due to serotonin syndrome risk.

Synthesized by Alexander Shulgin in 1974 and documented in his book PiHKAL. Unusually steep dose-response curve: 2mg more can dramatically change the experience. Combines mild visual effects with tactile and empathogenic warmth at lower doses, shifting to intense psychedelia above 25mg.

Originated in Colombia's nightclub scene in the late 2000s as a way to sell 2C-B. When 2C-B supply dried up, dealers kept the name and pink branding but switched to cheaper, locally available ingredients, typically ketamine, MDMA, and caffeine. The 'tusi' name is a phonetic Spanish rendering of '2C,' and 'pink cocaine' is pure marketing. Cocaine is almost never present. Tusi is now its own street-market product category with no consistent formula.

N,N-Dimethyltryptamine, found in hundreds of plant species and used for millennia in Amazonian ayahuasca traditions. The most intense psychedelic experience available; complete reality replacement when smoked. Produced endogenously in the human body in trace amounts, though its natural function is unknown.

Used by indigenous peoples of the Americas for at least 5,700 years, making it one of the oldest known psychedelics. Notably gentle, grounded character compared to LSD or mushrooms, but one of the longest-lasting psychedelics. Active doses are large (200-400mg), and nausea during onset is nearly universal.

Phencyclidine, developed as a surgical anesthetic in the 1950s and quickly withdrawn due to severe dissociative and psychotic side effects in patients. Unlike ketamine, PCP activates dopamine systems, contributing to both its addiction potential and psychosis risk. Effects are unpredictable and dose-dependent, ranging from euphoria to violent agitation to complete anesthesia.

First synthesized in 1944 by Leandro Panizzon; marketed as Ritalin in 1954, named after his wife Rita. The most widely prescribed stimulant globally. Unlike amphetamine, which forces monoamine release, methylphenidate blocks reuptake of dopamine and norepinephrine. Less euphoric, shorter-acting, and generally lower-risk. Combining with alcohol creates ethylphenidate through the same liver pathway that turns cocaine + alcohol into cocaethylene.

Synthetic cathinones are chemical cousins of amphetamine (specifically, beta-keto analogs, a small chemical tweak that adds one oxygen-containing group), originally derived from cathinone, a natural stimulant found in the khat plant. The first wave hit US emergency rooms in 2010-2011 as 'bath salts,' triggering 6,000 poison control calls in 2011 alone. The dominant compound in the supply changes every 1-3 years as each gets banned and chemists tweak the molecule to create an unscheduled replacement. Usually sold as MDMA/ecstasy, not by their actual names. This is a primary reason why roughly 1 in 4 ecstasy samples contains something other than MDMA.

Originally developed by Ciba-Geigy in the 1950s as morphine alternatives but never approved for medical use due to extreme potency and narrow safety margins. Rediscovered by illicit chemists after China's 2019 fentanyl ban. The first modern variant (isotonitazene, 'ISO') appeared in the US Midwest in 2019 and was linked to at least 40 deaths around Chicago and Milwaukee in seven months. Built on a completely different chemical skeleton from both morphine and fentanyl: a benzimidazole ring system instead of the morphinan (morphine/heroin) or piperidine (fentanyl) frameworks. Because the molecule looks different, standard drug tests don't catch it. At least 26 variants identified by early 2025 across Asia, Europe, North America, Oceania, and South America. China banned the class in July 2025, which may shift production elsewhere.