Browse all articles

Home Get the app
Caffeine

Caffeine

Best for

Sharpen accuracy and agility in sport

Likely strong benefit · 1–10 mg/kg/day for 0 weeks · 6 meta-analyses , n=3.5k

94 papers · 18 claims · 123 outcomes scored · 10 positive

Evidence summary

Evidence summary

Likely strong benefit

Caffeine delivers likely strong benefit for alertness, memory, and sport performance, with the clearest gains when fatigue, reaction time, and training output matter.

  • Across 13 studies (n=3,460), caffeine improved sport accuracy and agility.2
  • Across 6 studies (n=190), caffeine strengthened memory performance.1
  • Caffeine's evidence base spans 94 papers and 123 outcomes across cognition and exercise.

Outcomes

What caffeine actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Sharpen accuracy and agility in sport Likely strong benefit

Execute skills more precisely when fatigue and pressure mount.

13 meta-analyses n=3.5k 1–10 mg/kg 0 wk #1/14
21324203·35010566·37815006·36297081 +9 more
Strengthen your memory Likely strong benefit

Names, conversations, faces, and details stick instead of dissolving.

6 meta-analyses n=190 80–450 mg 1 wk #4/42
33201262·20464765·19777214·25389379 +2 more
Sharpen focus and mental stamina Promising early signal

Concentrate longer, resist distraction, and stay mentally sharp through demanding tasks.

15 meta-analyses n=451 1.2–800 mg 0–1 wk #2/40
20464765·25527035·33364521·40704635 +11 more
Cut caffeine dependence Promising early signal

Makes caffeine feel less essential and tapering less punishing.

4 RCTs n=197 100 mg 1–27 wk
26501499·30580203·41156489·2794839
Wake up clear-headed Studies contradict

Less grogginess, more energy from the moment you open your eyes.

7 RCTs n=149 6–800 mg/kg 0–3 wk #6/14
31480553·34024173·19241060·25527035 +3 more
Last longer before giving out Proven modest benefit

More reps, more miles, and a higher ceiling before fatigue forces you to stop.

25 meta-analyses n=3.9k 1.3–474.78 mg 1 wk #1/40
21526071·25389379·36615805·38568259 +21 more
Reduce everyday fatigue Faint early signal

Less of that heavy, worn-out feeling that makes simple tasks feel like a chore.

4 RCTs n=102 3–400 mg 3 wk
19241060·35684105·40369047·2794839
Sharpen reasoning and problem solving Faint early signal

See patterns faster and solve logic problems with less effort.

3 meta-analyses n=55 200–800 mg 0 wk #2/6
20464765·33201262·33364521
Speed up mental arithmetic Faint early signal

Calculate faster and hold accuracy when numbers pile up.

1 RCT n=32 200 mg — #1/4
33201262
Speed up thinking and reactions Barely detectable

Shortens the gap between seeing a question and having the answer.

10 meta-analyses n=355 1.2–800 mg 0–1 wk
19777214·20464765·33201262·33800853 +6 more
Blunt blood pressure spikes Proven modest benefit

Keeps your numbers steadier when stress, caffeine, or exertion hits.

10 meta-analyses n=1.5k 50–600 mg 1–5 wk
12392588·25716925·39377163·39747536
Fall asleep faster Faint negative signal

Shrinks the gap between hitting the pillow and actually sleeping.

5 meta-analyses n=386 6–450 mg 1–5 wk
31480553·33013662·33633278·36870101 +1 more
Smooth out coffee jitters Not enough research

Buffers the anxious, shaky edge some people get from coffee.

1 meta-analysis n=— 12.5–720 mg —
41549915
Ease caffeine withdrawal symptoms Not enough research

Smooths out the headache, fog, and slump when cutting back on caffeine.

1 RCT n=— 450 mg 1 wk
33633278
Lower day-to-day anxiety Likely somewhat harmful

The background hum of worry that colors everything gets quieter.

3 meta-analyses n=650 3–300 mg/kg —
40977612
Ease anxiety in older adults Likely somewhat harmful

Quiets the health worries and body tension that build with age.

2 meta-analyses n=626 300 mg —
Reduce pre-competition anxiety Likely somewhat harmful

Quiets the overthinking that hijacks execution right before you compete.

2 meta-analyses n=626 300 mg —
Lower your blood pressure May have slight negative effect

Brings down both systolic and diastolic, especially when baseline runs high.

8 meta-analyses n=949 0–600 mg 1–5 wk
15882556·1747643·25716925·34577880 +4 more

Forms & standardisation

The best-studied forms are plain caffeine anhydrous in capsules or tablets, plus coffee and energy drinks in real-world trials 23. On a label, look for the exact milligrams of caffeine per serving, because trial doses are built on known amounts, not mystery blends. Caffeine gum and fast-dissolve products hit faster than a capsule, which makes them handy when you want a quick pre-workout lift 23.

Risk profile

Adverse events and known drug interactions

Safety events

myocardial_infarction severe
stroke severe
arrhythmia severe
seizure severe
psychosis severe
rhabdomyolysis severe
hepatotoxicity severe
exertional_heat_illness severe

Drug interactions

Antihypertensives major decreases effect
Antidepressants major increases toxicity
other major increases concentration
Carbamazepine major decreases effect
Phenobarbital major decreases effect
Phenytoin major decreases effect
Gabapentin major decreases effect
Levetiracetam major decreases effect
Pregabalin major decreases effect
Topiramate major decreases effect

Co-studied with

Supplements that share evidence with caffeine

Theanine 20 shared outcomes · d=0.60
Taurine 13 shared outcomes · d=0.99
Glucuronolactone 13 shared outcomes · d=0.99
Glucose 13 shared outcomes · d=0.99
Tyrosine 11 shared outcomes · d=0.50

Frequently asked

Common questions

How much caffeine should I take for focus?

A lot of the attention studies land in the 80–200 mg range, with bigger doses like 200–500 mg showing up in harder mental tasks 14. Start low, because more caffeine does not automatically mean better focus, and the sleep cost rises fast 5.

Is caffeine good before a workout?

Yes, this is one of caffeine's strongest uses. Trials commonly use 3–6 mg/kg about 30–60 minutes before exercise, and the clearest wins show up in endurance, power, and skill under fatigue 23.

Does caffeine cause anxiety?

In sensitive people, yes, it can push anxiety, jitters, and a racing heart in the wrong direction 6. The risk climbs with bigger doses, and people who already feel wired or on edge tend to notice it first 67.

Will caffeine mess with my sleep?

It often does. Caffeine can make it harder to fall asleep and can leave you less refreshed the next morning, even when you do not feel obviously stimulated anymore 5.

Track caffeine in the app

Log doses, check interactions, compare it to alternatives — all backed by the same evidence base.

One email when we launch. No spam, no selling.

Sources

  1. 1. Is caffeine a cognitive enhancer? (2010) ↑
  2. 2. Caffeine and exercise performance: a review and meta-analysis (2017) ↑
  3. 3. International Society of Sports Nutrition position stand: caffeine and exercise performance (2019) ↑
  4. 4. Caffeine as an attention enhancer (2012) ↑
  5. 5. Caffeine and sleep: a review (2015) ↑
  6. 6. Caffeine and anxiety: a critical review of the evidence (2018) ↑
  7. 7. The effect of caffeine on blood pressure: a meta-analysis (2006) ↑

Generated May 15, 2026

Want personalized recommendations?

Show me what works for me