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59

Caffeine

Also known as: 1,3,7-Trimethylxanthine

Stimulant

Nootropic
A

Tier A

Meta-analysis of RCTs (n>500)

T1Full ProfileAcute

Most widely used psychoactive substance. Blocks adenosine receptors to promote wakefulness and enhance cognitive performance.

Mechanism of Action

Competitive antagonist at adenosine A1 and A2A receptors. Increases dopamine and norepinephrine signaling indirectly.

Usage Tips

  • Combine with L-theanine (2:1 ratio) for smooth focus
  • Avoid after 2pm to protect sleep quality
  • Tolerance builds quickly - consider cycling
  • Take with food to reduce GI discomfort

Contraindications

  • Severe anxiety disorders
  • Uncontrolled hypertension
  • Cardiac arrhythmias
  • Pregnancy (high doses)

Performance Profile

Physical Energy
+4
Mental Stamina
+3
Alertness
+4
Motivation
+3

Dosage

50mg

min

100mg

400mg

max

Timing

Best time

Morning

15 min

onset

4 hr

duration

Half-life
5 hr

Safety & Legal

9/10

Well-tolerated

Legal Status

OTC

Mild
Moderate
Severe
Jitteriness
1-10%mild
Increased heart rate
1-10%mild
Insomnia
1-10%moderate
Anxiety
0.1-1%moderate
Gastrointestinal upset
1-10%mild