guarana + caffeine medications
Guarana seeds are an unusually concentrated source of caffeine, carrying several times the caffeine of coffee beans, and that caffeine adds directly to any caffeine-containing medication (such as Excedrin, Fioricet, Cafergot, Anacin, Esgic, NoDoz, or Vivarin). Because the caffeine is additive and easy to overlook, stacking guarana on top of these products can push total caffeine intake into a range linked to tachycardia, hypertension, jitteriness, GI upset, insomnia, and — in published case reports — serious cardiac arrhythmias.
