The claimEvidence B · meta-analysis
Energy drink + coffee is stronger
The evidence
300-400 mg of caffeine plus sugar, taurine and guarana: the US Food and Drug Administration's adverse-event system (MedWatch) has repeatedly logged acute heart-rhythm disturbances and high-blood-pressure events.
The mechanism, in brief
You are not sleepy, but not because there is a lot of caffeine in your blood — it is because adenosine has been blocked.
Sources (2)
- Wesensten, N. J., Belenky, G., Kautz, M. A., Thorne, D. R., Reichardt, R. M., & Balkin, T. J. (2002). Maintaining alertness and performance during sleep deprivation: modafinil versus caffeine. Psychopharmacology, 159(3), 238–247.
- EFSA Panel on Dietetic Products, Nutrition and Allergies. (2015). Scientific opinion on the safety of caffeine. EFSA Journal, 13(5), 4102. Abstract: single doses up to 200 mg (about 3 mg/kg bw for a 70-kg adult) and habitual intake up to 400 mg per day raise no safety concerns for non-pregnant adults; up to 200 mg per day in pregnancy raises no concern for the fetus; single doses and habitual intake up to 200 mg by lactating women raise no concern for breastfed infants; for children and adolescents the data were insufficient to derive a safe intake, and the Panel suggests the adult 3 mg/kg bw per day as a basis. Typical energy-drink constituents, and alcohol up to about 0.65 g/kg bw, would not affect the safety of single caffeine doses up to 200 mg (abstract, Wiley page via Wayback snapshot 8 January 2025).