Guarana: benefits, dosage & side-effects

Written by Jack Feeney on January 14, 2019 Reviewed by Gabriella Clarke on January 31, 2019

Guarana is available in tablets and capsules – either on its own or combined with other ingredients, often with ginseng. You can also find it in guarana drinks and smoothies.

Guarana seeds contain powerful antioxidants, including tannins, saponins and catechins,³ plus plant chemicals which stimulate the central nervous system, according to a 2010 study by the University of Florida.⁴ These include: 

As a result of these stimulants, scientists think guarana may have the following effects: It can reduce feelings of tiredness Guarana has energising effects on the body, relieving fatigue and weakness, according to the European Medicines Agency.⁷ Indeed, a 2008 study by Northumbria University found that people who drank a cocktail of guarana, vitamins and minerals felt less tired after performing a series of mentally challenging tasks than those who drank a placebo.⁸

There are no official guidelines on how much guarana is safe to consume, but 75mg has been shown to have a positive effect.¹⁴ Guarana shouldn’t be taken by:^15,16

Taken in excess, at doses of 250-300mg, guarana can produce similar symptoms to a high-caffeine intake including:¹⁷