1950s – the subject of medical research into their anti-depressant properties. for all of the above reasons, the use of medicinal scopolamine for recreational uses is also observed. analgesics further information: analgesic analgesics (also known as "painkillers") are used to relieve pain (achieve analgesia). the word analgesic derives from greek "αν-" (an-, "without") and "άλγος" (álgos, "pain"). analgesic drugs act in various ways on the peripheral and central nervous systems; they include paracetamol (also known in the us as acetaminophen), the nonsteroidal anti-inflammatory drugs (nsaids) such as the salicylates (e.g. aspirin), and opioid drugs such as hydrocodone, codeine, heroin and oxycodone. some further examples of the brand name prescription opiates and opioid analgesics that may be used recreationally include vicodin, lortab, norco (hydrocodone), avinza, kapanol (morphine), opana, paramorphan (oxymorphone), dilaudid, palladone (hydromorphone), and oxycontin (oxycodone). tranquilizers further information: tranquilizer the following are examples of tranquilizers (gabaergics): barbiturates benzodiazepines ethanol (drinking alcohol; ethyl alcohol) nonbenzodiazepines others carisoprodol (soma) chloral hydrate diethyl ether ethchlorvynol (placidyl; "jelly-bellies") gamma-butyrolactone (gbl, a prodrug to ghb) gamma-hydroxybutyrate (ghb; g; xyrem; "liquid ecstasy", "fantasy") glutethimide (doriden) kava (from piper methysticum; contains kavalactones) ketamine, a phencyclidine (pcp) analog meprobamate (miltown) methaqualone (sopor, mandrax; "quaaludes") phenibut propofol (diprivan), a general anesthetic theanine (found in camellia sinensis, the tea plant) valerian (from valeriana officinalis) stimulants further information: stimulant cocaine is a commonly used stimulant. stimulants, also known as "psychostimulants", induce euphoria with improvements in mental and physical function, such as enhanced alertness, wakefulness, and locomotion. stimulants are also occasionally called "uppers". depressants or "downers", which decrease mental or physical function, are in stark contrast to stimulants and are considered to be their functional opposites. stimulants enhance the activity of the central and peripheral nervous systems. common effects may include increased alertness, awareness, wakefulness, endurance, productivity, and motivation, arousal, locomotion, heart rate, and blood pressure, and a diminished desire for food and sleep. use of stimulants may cause the body to significantly reduce its production of endogenous compounds that fulfill similar functions. once the effect of the ingested stimulant has worn off the user may feel depressed, lethargic, confused, and dysphoric. this is colloquially termed a "crash" and may promote reuse of the stimulant. amphetamines are a significant cause of drug-induced psychosis. importantly, a 2019 meta-analysis found that 22% of people with amphetamine-induced psychosis transition to a later diagnosis of schizophrenia. examples of stimulants include: sympathomimetics (catecholaminergics)—e.g. amphetamine, methamphetamine, cocaine, methylphenidate, ephedrine, pseudoephedrine entactogens (serotonergics, primarily phenethylamines)—e.g. mdma (which is also an amphetamine) eugeroics, e.g. modafinil others arecoline (found in areca catechu) caffeine (found in coffea spp.) nicotine (found in nicotiana spp.) rauwolscine (found in rauvolfia serpentina) yohimbine (procomil; a tryptamine alkaloid found in pausinystalia johimbe) euphoriants further information: euphoriant alcohol: "euphoria, the feeling of well-being, has been reported during the early (10–15 min) phase of alcohol consumption" (e.g., beer, wine or spirits) cannabis: tetrahydrocannabinol, the main psychoactive ingredient in this plant, can have sedative and euphoric properties. catnip: catnip contains a sedative known as nepetalactone that activates opioid receptors. in cats it elicits sniffing, licking, chewing, head shaking, rolling, and rubbing which are indicators of pleasure. in humans, however, catnip does not act as a euphoriant. stimulants: "psychomotor stimulants produce locomotor activity (the subject becomes hyperactive), euphoria, (often expressed by excessive talking and garrulous behaviour), and anorexia. the amphetamines are the best known drugs in this category..." mdma: the "euphoriant drugs such as mdma ('ecstasy') and mdea ('eve')" are popular among young adults. mdma "users experience short-term feelings of euphoria, rushes of energy and increased tactility" as well as interpersonal connectedness. opium: this "drug derived from the unripe seed-pods of the opium poppy…produces drowsiness and euphoria and reduces pain. morphine and codeine are opium derivatives." opioids have led to many deaths in the united states, particularly by causing respiratory depression. hallucinogens further information: hallucinogen