Creatine vs Caffeine
for energy / fatigue
Stronger evidence: Caffeine
Stronger effect: Caffeine
Safety: Caffeine carries a minor interaction; Creatine has none recorded.
For energy / fatigue, Caffeine has the stronger evidence grade.
Creatine
grade C low certainty
may reduce mental fatigue, especially under sleep deprivation or stress
3–5 g/day, adults
Caffeine
grade B moderate certainty
reduces perceived fatigue; tolerance develops with regular use
40–200 mg
sources: PMID:20000106 · PMID:00000021