Know2eat

Caffeine anhydrous

Isolated Compounds

What caffeine anhydrous may help with

Ranked by how strong the human evidence is — best supported first.

Best supportedAlertness and energyStrong evidence· 3 sources

Then, in order

About Caffeine anhydrous

Dehydrated crystalline caffeine, sold as tablets, capsules and — dangerously — as bulk powder. It is chemically identical to the caffeine in coffee, delivered without the volume that ordinarily limits how much anyone consumes.

Caffeine is the best-evidenced performance and alertness compound available, with hundreds of trials, several large meta-analyses and a consistent effect across endurance, repeated sprints, strength and vigilance. Effective doses are lower than most people assume, around 3 to 6 milligrams per kilogram, and going higher mostly adds side effects. The anhydrous form is worth treating differently from coffee for one reason: bulk caffeine powder has killed people. A level teaspoon of pure powder contains roughly the caffeine of twenty-five to thirty cups of coffee, kitchen scales cannot weigh a safe dose accurately, and after several deaths in otherwise healthy young people the US regulator declared bulk pure and highly concentrated caffeine products in supplement form unlawful.

Sold as
Tablet, Capsule, Pre-workout powder blend, Energy gum, Bulk powder (subject to US enforcement)
Standardised to
Milligrams of anhydrous caffeine; pre-workout blends frequently combine several caffeine sources and understate the total — a product without this marker may not resemble what was studied.
Also known as
Pure caffeine, Caffeine powder, Caffeine tablets, 1,3,7-trimethylxanthine

Regulation: US regulators issued guidance declaring bulk pure and highly concentrated caffeine sold directly to consumers unlawful, following deaths from powder overdose, and have taken enforcement action against distributors. Caffeine was removed from the WADA prohibited list in 2004 but remains on the monitoring programme. Several countries limit caffeine in energy drinks and require warning labels.

What the research used

The amounts, forms and durations published trials of Caffeine anhydrous actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

  • Studied for Exercise performance

    3–6 mg

    Strong

    Per kilogram of body weight, 30–60 minutes before exercise

    The dose range across the trial literature, roughly 200–450 mg for most adults. Doses above 6 mg/kg do not perform better and produce more tremor, tachycardia and gastrointestinal upset.

  • Studied for Alertness and vigilance

    75–200 mg

    Strong

    Tablet or capsule

    Effects on reaction time and sustained attention appear at doses as low as 75 mg. Much of the perceived benefit in habitual users is reversal of overnight withdrawal rather than enhancement above baseline.

  • Studied for Regulatory intake guidance

    400 mg

    Moderate

    Total daily intake from all sources for healthy adults

    European and Canadian authorities identify around 400 mg daily, and 200 mg in a single dose, as not raising safety concerns for most healthy adults, with 200 mg daily the figure used in pregnancy.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

Each timing below was actually compared against an alternative in a trial, which is unusual.

  • Evening

    Strong

    The sleep cut-off is real pharmacology, not folklore. Caffeine has a half-life of roughly five hours in most adults, longer in pregnancy and with some medications, and a controlled trial giving 400 mg at bedtime, three hours before bed and six hours before bed found measurable sleep disruption at all three timings — including the six-hour one, which participants did not notice. A cut-off in the early afternoon is the conservative reading for anyone who sleeps poorly.

    Timing was tested. A trial compared this window against another and reported a difference.

  • Before exercise

    Moderate

    Trials dose 30 to 60 minutes before exercise, which matches the time to peak plasma concentration. Chewing gum formulations peak faster, at around 10 to 15 minutes, and this has been compared directly.

    Timing was tested. A trial compared this window against another and reported a difference.

The evidence in depth

Best supported: Strong

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.

Alertness and energy

Energy & Metabolism
Strong evidence

Caffeine reliably improves reaction time, vigilance and subjective alertness, with the largest effects in sleep-deprived people and in habitual users who have gone without it. In non-deprived, non-withdrawn people the improvement over baseline is smaller than most users assume.

Strong evidence. Consistent findings across multiple good-quality human studies.

View the 3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Exercise performance

Muscle & Physical Performance
Strong evidence

Umbrella reviews of many meta-analyses show caffeine improves endurance performance, muscular strength, muscular endurance, jumping and sprint performance. It is the most consistently effective legal ergogenic aid after creatine, with effects present across trained and untrained participants.

What may be going on: Caffeine antagonises adenosine receptors in the central nervous system, reducing perceived effort and increasing motor unit recruitment. Peripheral effects on calcium handling contribute at higher concentrations.

Strong evidence. Consistent findings across multiple good-quality human studies.

View the 2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Body composition

Weight Management
Limited evidence

Caffeine raises energy expenditure and fat oxidation acutely, and meta-analyses report small effects on body weight and fat mass. Tolerance to the thermogenic effect develops, and the long-term contribution to weight is minor.

Limited evidence. Early human work, or mostly lab and animal research.

View the 4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

  • Too much

    Pure caffeine powder has killed healthy young people

    Bulk caffeine powder is concentrated enough that a single teaspoon can approach or exceed a lethal dose — roughly the caffeine of twenty-five to thirty cups of coffee. Deaths have occurred in otherwise healthy young men who measured it with kitchen equipment that cannot resolve the difference between a safe dose and a fatal one. US regulators declared these products unlawful for this reason. Nobody should be weighing caffeine powder at home.

  • Too much

    Overdose causes arrhythmia and seizures

    Caffeine toxicity produces vomiting, agitation, tachycardia, arrhythmia, hypokalaemia and seizures, and can be fatal. Risk rises sharply with combined sources — pre-workout powder plus energy drinks plus coffee — and pre-workout blends often list several caffeine-containing ingredients without a stated total.

  • Worth knowing

    Pregnancy, adolescence and cardiac conditions

    Health authorities advise limiting caffeine to around 200 mg daily in pregnancy, where the half-life lengthens considerably. Concentrated caffeine is not appropriate for children or adolescents, and anyone with an arrhythmia, uncontrolled hypertension or an anxiety disorder should be cautious at any dose.

  • Interaction

    Metabolised by CYP1A2, with several interactions

    Interacts withFluvoxamine, ciprofloxacin, oral contraceptives, theophylline, clozapine, lithium

    Fluvoxamine, ciprofloxacin and oral contraceptives slow caffeine clearance substantially, raising effective exposure; smoking accelerates it. Caffeine also interacts with theophylline, some antipsychotics and with lithium excretion.

  • Worth knowing

    Withdrawal is real and the effect is partly restorative

    Regular use produces dependence, and stopping causes headache, fatigue and low mood for several days. Much of the alertness a habitual user experiences is the reversal of overnight withdrawal rather than a gain above their unmedicated baseline.

In the food catalogue

The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.

CoffeeThe everyday source, delivering roughly 80–120 mg per cup along with…Green teaA lower-caffeine source that also supplies theanine, which alters the…

Evidence ratings on this page: 2 strong evidence, 1 limited evidence.

Supplements are sold in the US without pre-market review of efficacy or safety. Nothing on this page is a recommendation to take Caffeine anhydrous, or a dose to follow.