Caffeine Trivia
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48 free Caffeine trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Caffeine is the most widely consumed psychoactive drug on Earth, legal almost everywhere and swallowed at a rate of 120,000 tonnes a year. This quiz covers the science: how it blocks adenosine to keep you awake, why plants make it as a pesticide, its half-life and what smoking, the pill and pregnancy do to it, the doses that are safe, the doses that are lethal, and the odd corners of medicine where it treats premature babies and boosts painkillers. It also covers the history and the products: Runge and Goethe's coffee beans in 1819, Emil Fischer's synthesis, the kings who banned coffee, the US government's 1911 seizure of Coca-Cola, Roselius and the seawater that invented decaf, Lipovitan, Krating Daeng and Red Bull, Monster and the energy shot, plus kola nuts, yerba mate, gyokuro tea and the Mormon reading of 'hot drinks'. It suits coffee drinkers, science quiz fans and anyone who has wondered whether the fourth cup is a good idea. Every answer was checked against Wikipedia's articles on caffeine, decaffeination, energy drinks and Red Bull, and each question shows its supporting sentence after you answer.
30 of 48 questions with answers and explanations. Play the quiz
Q 01Caffeine keeps you awake mainly by blocking the receptors of which sleep-promoting molecule?
Adenosine
Adenosine builds up in the brain the longer you stay awake and makes you drowsy; caffeine is shaped enough like it to sit in its receptors without switching them on.
Q 02In the legend of coffee's discovery, the Ethiopian herder Kaldi saw which animals turn frisky after eating the berries?
Goats
Goats: in one telling Kaldi took the berries to a nearby monastery, where the abbot brewed them into a drink to stay awake through the long evening prayers.
Q 03Which composer wrote a comic 'Coffee Cantata' about a daughter who refuses to give up her coffee habit?
Johann Sebastian Bach
Johann Sebastian Bach wrote it in the 1730s, when he led the ensemble at a Leipzig coffee house; the daughter yields when her father threatens she will get no husband, then secretly spreads word that any suitor must let her drink coffee.
Q 04Which South African herbal tea is naturally caffeine-free?
Rooibos
Rooibos comes from a South African shrub in the pea family, not from the tea plant, so its leaves hold no caffeine at all.
Q 05Why do plants such as coffee and tea make caffeine in the first place?
As a natural pesticide against insects
As a natural pesticide against insects: at the doses found in the plants it puts bugs off feeding and can kill them, a defence so useful that coffee and tea evolved it separately.
Q 06Caffeine has been found to enhance the reward memory of which animals, encouraging them to return to a plant?
Honey bees
Honey bees: coffee and citrus flowers lace their nectar with a dose too weak for the bees to taste, yet strong enough to fix the flower's scent in their memory.
Q 07Which Amazonian seed, a staple of South American soft drinks, holds more caffeine than a coffee bean?
Guarana
Guarana seeds are far richer in caffeine than coffee beans, weight for weight, which is why their extract turns up in so many energy drinks.
Q 08Members of which church follow a health code that bans 'hot drinks', meaning coffee and tea, but never mentions caffeine?
Latter-day Saints
Latter-day Saints: their revelation on health bars 'hot drinks', which leaders read as tea and coffee, and says nothing of caffeine, so in 2012 the church corrected a TV report claiming members may not have caffeine.
Q 09Which famous writer handed a young chemist a box of coffee beans to analyse in 1819, leading to the discovery of caffeine?
Goethe
Goethe had invited the young Friedlieb Runge to demonstrate how a plant extract widens a cat's pupils, then sent him off with the beans, from which Runge soon isolated caffeine.
Q 10Which fruity malt liquor lost its caffeine in 2010, the year the FDA called the stimulant an 'unsafe food additive' in alcohol?
Four Loko
Four Loko was reformulated in December 2010 after several states banned it; the FDA had warned that caffeine can hide the cues drinkers rely on to judge how intoxicated they are.
Q 11The US government once seized 40 barrels and 20 kegs of which product, alleging its caffeine was 'injurious to health'?
Coca-Cola syrup
Coca-Cola syrup: the 1909 seizure became a Supreme Court case named after the barrels and kegs, and in 1916 the justices overturned the company's early win and sent it back for trial.
Q 12Which English king tried to shut down England's coffeehouses?
Charles II
Charles II called the coffeehouses haunts of 'idle and disaffected persons' who spread false reports about his government, but the ban raised such an outcry that it was withdrawn.
Q 13About how much caffeine a day do European and US regulators consider safe for a healthy adult?
About 400 mg
Q 21Which over-the-counter pain reliever combines aspirin and acetaminophen with caffeine to boost its effect?
Excedrin
Excedrin: pooled trials found that 100 mg or more of caffeine lets roughly 5 to 10 more people in every hundred get good relief from the same dose of painkiller.
Q 22Caffeine was once used as a second-line treatment for which condition?
ADHD
ADHD: caffeine beat placebo in trials but lost out to drugs such as methylphenidate, and people with ADHD still tend to drink more of it, perhaps to self-medicate.
Q 23Which amino acid found in tea has synergistic alerting effects when taken with caffeine?
L-theanine
L-theanine: pooled trials found the tea compound and caffeine together sharpened alertness and attention-switching in the first two hours after a dose, and supplement makers sell the two as a pair.
About 400 mg: Europe's food-safety authority and the FDA both cite that figure for healthy adults, while the FDA says seizures can follow when around 1,200 mg is swallowed quickly.
Q 14Ounce for ounce, which coffee drink delivers the most caffeine?
Espresso
Espresso is by far the most concentrated, yet a single shot holds less caffeine than a mug of drip coffee simply because the serving is so small.
Q 15Which body moved caffeine off its list of banned substances in 2004 and onto a watch list?
World Anti-Doping Agency
World Anti-Doping Agency: tests in the four years after the change found caffeine in about three of every four urine samples taken at competitions, but hardly any above the old limit.
Q 16Which caffeine product, linked to at least two deaths, did the FDA curb with new guidance in 2018?
Pure caffeine powder
Pure caffeine powder: one teaspoon can hold as much caffeine as 28 cups of coffee, and the FDA says a safe serving is too small to measure with kitchen spoons.
Q 17About how long does a healthy adult's body take to clear half of a dose of caffeine?
About 5 hours
About 5 hours, within a normal range of three to seven, so half of a mid-afternoon coffee can still be circulating at bedtime; a newborn needs days to do the same.
Q 18Regular smokers tend to drink more coffee, possibly because tobacco smoke does what to caffeine in the body?
Speeds up its breakdown
Speeds up its breakdown: chemicals in the smoke rev up the liver enzymes that clear caffeine, so a smoker gets a shorter lift from every cup.
Q 19Caffeine citrate is on the WHO's list of essential medicines for treating which condition?
Apnea in premature babies
Apnea in premature babies: their immature brains sometimes stop sending the signal to breathe, and caffeine stimulates the brain's breathing centres until they catch up.
Q 20Regular caffeine consumption may reduce the risk of which neurological condition?
Parkinson's
Parkinson's: large long-term studies keep finding fewer cases among people who take in more caffeine, and in animal experiments the drug shields the brain from the damage.
Q 24Which British financial institution grew out of a coffeehouse where ship owners and merchants met to trade news?
Lloyd's of London
Lloyd's of London began in Edward Lloyd's coffee house, where shippers and underwriters met to insure voyages, and it still carries the name of the man who served the coffee.
Q 25According to a popular story, which leader tasted coffee, condemned by clergy as 'Satan's drink', and approved it for Christians?
Pope Clement VIII
Pope Clement VIII is said to have tried a cup when his advisers urged him to ban it, and to have joked that the drink was too delicious to leave to the infidels.
Q 26Which symptom is the hallmark of caffeine withdrawal?
Headache
Headache typically sets in within a day of the last cup, when blood flow in the brain, held down by caffeine, rebounds; it can linger for several days.
Q 27Which Indonesian island, where the Dutch planted coffee in the 1600s, became a nickname for the drink itself?
Java
Java: the Dutch shipped its beans to Europe as 'Java coffee', a name later clipped to 'java', and by the early 1900s the word meant any coffee at all.
Q 28Ludwig Roselius's first commercial decaf process washed the caffeine out of the beans with which chemical, now a known carcinogen?
Benzene
Benzene: Roselius's Kaffee HAG process rinsed moistened green beans with it to carry off the caffeine, and decaf makers dropped it once its dangers were understood.
Q 29Decaf coffee was first made commercially in the 1900s, as Kaffee HAG, by a company in which country?
Germany
Germany: a Bremen coffee merchant launched the first commercial decaf there, and the caffeine that decaf factories strip out is sold on to makers of soft drinks.
Q 30The Swiss Water decaffeination process is distinctive because it avoids what?
Any organic solvent
Any organic solvent: only water and charcoal filters touch the beans, and despite its name the process is now run from a plant in British Columbia, Canada.