Query: Small amounts of very active substances can cause large effects.

Relevant passages:
Lysergic acid diethylamide <=SEP=> Lysergic acid diethylamide ( LSD ) , also known as acid , is a psychedelic drug known for its psychological effects . This may include altered awareness of the surroundings , perceptions , and feelings as well as sensations and images that seem real though they are not . It is used mainly as a recreational drug and for spiritual reasons . LSD is typically either swallowed or held under the tongue . It is often sold on blotter paper , a sugar cube , or gelatin . It can also be injected .   LSD is not addictive . However , adverse psychiatric reactions such as anxiety , paranoia , and delusions are possible . LSD is in the ergoline family . LSD is sensitive to oxygen , ultraviolet light , and chlorine , though it may last for years if it is stored away from light and moisture at low temperature . In pure form it is odorless and clear or white in color . As little as 20 -- 30 micrograms can produce an effect .   LSD was first made by Albert Hofmann in Switzerland in 1938 from ergotamine , a chemical from the fungus ergot . The laboratory name for the compound was the acronym for the German `` Lyserg-säure-diäthylamid '' , followed by a sequential number : LSD-25 . Hofmann discovered its psychedelic properties in 1943 . LSD was introduced as a commercial medication under the trade-name Delysid for various psychiatric uses in 1947 . In the 1950s , officials at the U.S. Central Intelligence Agency ( CIA ) thought the drug might be useful for mind control and chemical warfare and tested the drug on young servicemen and students , and others without their knowledge . The subsequent recreational use by youth culture in the Western world as part of 1960s counterculture resulted in its prohibition .

Alcohol (drug) <=SEP=> Alcohol, sometimes referred to by the chemical name ethanol, is a psychoactive drug that is the active ingredient in drinks such as beer, wine, and distilled spirits (hard liquor). It is one of the oldest and most common recreational substances, causing the characteristic effects of alcohol intoxication ("drunkenness"). Among other effects, alcohol produces a mood lift and euphoria, decreased anxiety, increased sociability, sedation, impairment of cognitive, memory, motor, and sensory function, and generalized depression of central nervous system function. Ethanol is only one of several types of alcohol, but it is the only type of alcohol that is found in alcoholic beverages or commonly used for recreational purposes; other alcohols such as methanol and isopropyl alcohol are significantly more toxic.  A mild, brief exposure to isopropanol, being only moderately more toxic than ethanol, is unlikely to cause any serious harm.  Methanol, being profoundly more toxic than ethanol, is lethal in quantities as small as 10–15 milliliters (2–3 tsp). Alcohol has a variety of short-term and long-term adverse effects. Short-term adverse effects include generalized impairment of neurocognitive function, dizziness, nausea, vomiting, and hangover-like symptoms. Alcohol can be addictive to humans, as in alcoholism, and can result in dependence and withdrawal. It can have a variety of long-term adverse effects on health, for instance liver damage, brain damage, and its consumption is the fifth leading cause of cancer. The adverse effects of alcohol on health are most important when it is used in excessive quantities or with heavy frequency. However, some of them, such as increased risk of certain cancers, may occur even with light or moderate alcohol consumption. In high amounts, alcohol may cause loss of consciousness or, in severe cases, death. Alcohol works in the brain primarily by increasing the effects of a neurotransmitter called γ-aminobutyric acid, or GABA. This is the major inhibitory neurotransmitter in the brain, and by facilitating its actions, alcohol suppresses the activity of the central nervous system. The substance also directly affects a number of other neurotransmitter systems including those of glutamate, glycine, acetylcholine, and serotonin. The pleasurable effects of alcohol ingestion are the result of increased levels of dopamine and endogenous opioids in the reward pathways of the brain. Alcohol also has toxic and unpleasant actions in the body, many of which are mediated by its byproduct acetaldehyde.Alcohol has been produced and consumed by humans for its psychoactive effects for almost 10,000 years. Drinking alcohol is generally socially acceptable and is legal in most countries, unlike with many other recreational substances. However, there are often restrictions on alcohol sale and use, for instance a minimum age for drinking and laws against public drinking and drinking and driving. Alcohol has considerable societal and cultural significance and has important social roles in much of the world. Drinking establishments, such as bars and nightclubs, revolve primarily around the sale and consumption of alcoholic beverages, and parties, festivals, and social gatherings commonly involve alcohol consumption. Its use is also related to various societal problems, including driving accidents and fatalities, accidental injuries, sexual assaults, domestic abuse, and violent crime. Alcohol remains illegal for sale and consumption in a number of countries, mainly in the Middle East.

Caffeine <=SEP=> Caffeine is a central nervous system ( CNS ) stimulant of the methylxanthine class . It is the world 's most widely consumed psychoactive drug . Unlike many other psychoactive substances , it is legal and unregulated in nearly all parts of the world . There are several known mechanisms of action to explain the effects of caffeine . The most prominent is that it reversibly blocks the action of adenosine on its receptor and consequently prevents the onset of drowsiness induced by adenosine . Caffeine also stimulates certain portions of the autonomic nervous system .   Caffeine is a bitter , white crystalline purine , a methylxanthine alkaloid , and is chemically related to the adenine and guanine bases of deoxyribonucleic acid ( DNA ) and ribonucleic acid ( RNA ) . It is found in the seeds , nuts , or leaves of a number of plants native to South America and East Asia and helps to protect them against predator insects and to prevent germination of nearby seeds . The most well known source of caffeine is the coffee bean , a misnomer for the seed of Coffea plants . Beverages containing caffeine are ingested to relieve or prevent drowsiness and to improve performance . To make these drinks , caffeine is extracted by steeping the plant product in water , a process called infusion . Caffeine-containing drinks , such as coffee , tea , and cola , are very popular ; in 2005 , 90 % of North American adults consumed caffeine daily .   Caffeine can have both positive and negative health effects . It can treat and prevent the premature infant breathing disorders bronchopulmonary dysplasia of prematurity and apnea of prematurity . Caffeine citrate is on the WHO Model List of Essential Medicines . It may confer a modest protective effect against some diseases , including Parkinson 's disease and certain types of cancer . One meta-analysis concluded that cardiovascular disease such as coronary artery disease and stroke is less likely with 3 -- 5 cups of non-decaffeinated coffee per day but more likely with over 5 cups per day . Some people experience insomnia or sleep disruption if they consume caffeine , especially during the evening hours , but others show little disturbance . Evidence of a risk during pregnancy is equivocal ; some authorities recommend that pregnant women limit consumption to the equivalent of two cups of coffee per day or less . Caffeine can produce a mild form of drug dependence -- associated with withdrawal symptoms such as sleepiness , headache , and irritability -- when an individual stops using caffeine after repeated daily intake . Tolerance to the autonomic effects of increased blood pressure and heart rate , and increased urine output , develops with chronic use ( i.e. , these symptoms become less pronounced or do not occur following consistent use ) .   Caffeine is classified by the Food and Drug Administration as `` generally recognized as safe '' ( GRAS ) . Toxic doses , over 10 grams per day for an adult , are much higher than typical doses of under 500 milligrams per day . A cup of coffee contains 80 -- 175 mg of caffeine , depending on what `` bean '' ( seed ) is used and how it is prepared ( e.g. drip , percolation , or espresso ) . Thus it requires roughly 50 -- 100 ordinary cups of coffee to reach a lethal dose . However pure powdered caffeine , which is available as a dietary supplement , can be lethal in tablespoon-sized amounts .