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Strong evidencePhysical performance

Caffeine

The world's most widely consumed stimulant. Improves aerobic performance, strength, focus, and alertness.

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What the science says

  • Improved physical performance Strong evidence

    An umbrella review of 21 meta-analyses confirms ergogenic effects on aerobic exercise, muscle strength, power, and anaerobic endurance.

  • Increased alertness and focus Strong evidence

    Reduces perceived fatigue and improves reaction time and vigilance, especially under sleep deprivation.

Dosage & safety

Studied dose3–6 mg/kg of body weight, 30–60 minutes before exercise. Avoid consumption late in the day.
SafetyHigh doses can cause insomnia, anxiety, and rapid heart rate. Individual tolerance varies widely (slow metabolizers feel more side effects). Up to 400 mg/day is generally cited as safe for healthy adults.

How to take it

Timing30-60 minutes before exercise, and at least 8-10 hours before bed if you want to protect your sleep.
With food?Either works; food slows the rise in blood levels slightly and reduces stomach upset.
Worth knowingRegular users still get most of the performance benefit — the 'wash-out period' before a competition is not supported and mostly buys you a withdrawal headache.

Interactions

With medications

  • strong CYP1A2 inhibitors (fluvoxamine, ciprofloxacin and some other quinolones, cimetidine)

    Caffeine clearance falls sharply and blood levels can rise several-fold, producing jitteriness, palpitations and insomnia at doses you normally tolerate. cut your usual caffeine intake substantially while on these drugs

  • theophylline and aminophylline

    Both are methylxanthines with the same mechanism and the same metabolic pathway, so effects and toxicity are additive. keep caffeine low and talk to your doctor before adding a supplement dose

  • stimulant medication and decongestants (ADHD stimulants, pseudoephedrine)

    Additive rises in heart rate, blood pressure and anxiety. do not stack a pre-workout dose on top of these without medical advice

With other supplements

  • synephrine (bitter orange) and yohimbine

    Additive cardiovascular stimulation — the combination drives most of the adverse-event reports attributed to pre-workout blends. avoid stacking stimulants, especially at high pre-workout doses

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does caffeine improve workout performance?

Yes — the evidence for caffeine is strong. An umbrella review of 21 meta-analyses confirms caffeine improves aerobic exercise, muscle strength, power and anaerobic endurance, and it also sharpens alertness and reaction time.

How much caffeine should I take before a workout?

The effective caffeine dose is 3–6 mg per kg of body weight, taken 30–60 minutes before exercise. Up to 400 mg/day of caffeine is generally cited as safe for healthy adults.

When should I stop drinking caffeine to protect my sleep?

Keep caffeine at least 8–10 hours before bed if you want to protect your sleep. High caffeine doses can cause insomnia, anxiety and a rapid heart rate, and tolerance varies widely between people.

Is caffeine safe to take with other medications?

Caffeine interacts with some drugs: strong CYP1A2 inhibitors such as fluvoxamine and ciprofloxacin can raise caffeine levels several-fold, and it adds to the effects of theophylline, ADHD stimulants and pseudoephedrine. Cut your caffeine substantially or get medical advice before stacking a pre-workout dose on these.

Scientific references

Where to buy

ALLMAX, Essentials, Caffeine, 200 mg, 100 Tablets

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