Like other sources of caffeine, guarana (e.g., coffee and tea) is recognized as a safe plant with a long history of use. Although complications and complaints are rare, in some cases side effects are possible.
Guarana, for example, can affect blood pressure, so it can have a negative effect if you are sensitive to caffeine or have high blood pressure. Additionally, eating too much of the ingredient can cause cramps and caffeine can contribute to the crash, while taking it too late in the day can disrupt your beauty sleep.
As Naidu points out, we all respond differently to caffeine, mainly due to the uniqueness of our liver metabolism genetics, as well as the microbiome of our personalized gut. That said, it’s important to pay attention to how you react to caffeinated ingredients – guarana or otherwise – and use that information to personalize the amount and timing of your intake.
To play it safe, avoid high levels of guarana, as you don’t need too much to reap the benefits. “Generally, a dose lower than 100 mg is sufficient to provide benefits,” notes Pasquarillo. It is also a good idea to consult with your healthcare provider before adding guarana to your routine, just as you would with any supplement, he adds.