Guarana is not considered dangerous when taken with the current average dosage by an average person; however, women who are pregnant or are nursing a baby and those who have cardiovascular disease or take any drugs with clozapine, lithium or theophylline should abstain, states Drugs.com. Guarana also can cause some negative side effects including insomnia and extreme nervous behavior.
Guarana is scientifically known as sorbilis, P. sorbilis and Paullinia cupana, according to Drugs.com. There is not a standard dosage of the substance as of 2015, but most people stay within the 200 to 800 milligram range per day, according to WebMD. Guarana is taken by most people as a way to stay alert because it has the highest caffeine concentration out of all plants, even higher than coffee and it is believed that it carries the ability to help people stay alert when they are tired.
The problem with using guarana is not so much related to its dangers, but rather that it does not have any data that backs its efficacy, reports WebMD. No one has found that guarana helps with cognitive ability, mood, athletic performance, sexual performance or other stimulant activities. Although there is evidence that guarana may be helpful with weight loss when taking it along with a variety of supplements, it is unclear whether or not the loss is due to the supplements or the guarana.