Guarana, an herb from the Amazon rain forest, has a long history of use as a stimulant beverage. It has also been used to treat arthritis, diarrhea, and headaches.

What is Guarana Used for Today?

Like tea, coffee, and chocolate, guarana contains alkaloids in the caffeine family, such as theobromine and theophylline. Caffeine is known to reduce pain, treat migraine headaches, and, of course, fight fatigue. In addition, it may, under certain circumstances, enhance sports performance, improve mental function, and modestly aid weight loss.

Most of the proposed uses of guarana fall into line with these effects of caffeine. For example, in a double-blind, placebo-controlled study of 129 healthy young adults, one-time use of guarana plus vitamins and minerals improved mental function and reduced mental fatigue among those undergoing a battery of cognitive tests.7 In another double-blind, placebo-controlled study, use of guarana alone or guarana plus ginseng appeared to improve mental function (though the study suffered from some design problems)1 In two other studies, no benefits were seen.2,3

Guarana has also been studied as a potential aid in fighting a common side effect of chemotherapy —fatigue.8 In one randomized trial, 75 breast cancer patients undergoing chemotherapy were randomized to receive guarana (50 mg twice daily for 21 days) or placebo. Since this trail had a crossover design , both groups received the herb and the placebo but at alternate times. At the end of the trial, researchers found evidence that guarana was helpful in reducing fatigue.

Another double-blind, placebo-controlled study tested the effects of guarana plus ephedra for weight loss.4 In this trial, a total of 67 overweight people were given either placebo or a combination of guarana and ephedra for a period of 8 weeks. The results showed significantly greater weight loss in the treated group than in the placebo group. However, ephedra is an unsafe substance. (See the Ephedra article for more information.)


A typical dose of guarana supplies 50 mg of caffeine, about half the amount in a cup of strong coffee. However, a 1998 analysis of products on the market indicated that many guarana products contain less than the advertised amount of guarana.5

Safety Issues

The side effects of guarana would be expected to be similar to those of tea or coffee, such as heartburn, gastritis, insomnia, anxiety, and heart arrhythmias (benign palpitations or more serious disturbances of heart rhythm).6 Combination products containing guarana and ephedra would be expected to present additional risk. Finally, all drug interactions that can occur with caffeine would be expected to occur with guarana as well (see Interactions You Should Know About).

Young children, pregnant or nursing women, or people with heart disease should not use guarana.

Interactions You Should Know About

If you are taking:

  • MAO inhibitors: The caffeine in guarana could cause dangerous drug interactions.
  • Stimulant drugs such as Ritalin: The stimulant effects of guarana might be amplified.
  • Drugs to prevent heart arrhythmias or treat insomnia or anxiety: Guarana might interfere with their action.



1. Kennedy DO, Haskell CF, Wesnes KA, et al. Improved cognitive performance in human volunteers following administration of guarana ( Paullinia cupana) extract: comparison and interaction with Panax ginseng. PharmacolBiochem Behav. 2004;79:401–11.

2. Galduroz JC, Carlini EA. The effects of long-term administration of guarana on the cognition of normal, elderly volunteers. Rev Paul Med. 1996;114:1073–8.

3. Galduroz JC, Carlini Ede A. Acute effects of the Paulinia cupana, "guarana" on the cognition of normal volunteers. Rev Paul Med. 1994;112:607–11.

4. Boozer CN, Nasser JA, Heymsfield SB, et al. An herbal supplement containing ma huang-guarana for weight loss: a randomized, double-blind trial. Int J Obes Relat Metab Disord. 2001;25:316–324.

5. Carlson M, Thompson RD. Liquid chromatographic determination of methylxanthines and catechins in herbal preparations containing guarana. J AOAC Int. 1998;81:691–701.

6. Cannon ME, Cooke CT, McCarthy JS. Caffeine-induced cardiac arrhythmia: an unrecognised danger of healthfood products. Med J Aust. 2001;174:520–1.

7. Kennedy DO, Haskell CF, Robertson B, et al. Improved cognitive performance and mental fatigue following a multi-vitamin and mineral supplement with added guarana ( Paullinia cupana). Appetite. 2007 Oct 30.

8. de Oliveira Campos MP, Riechelmann R, Martins LC, Hassan BJ, Casa FB, Del Giglio A. Guarana (Paullinia cupana) improves fatigue in breast cancer patients undergoing systemic chemotherapy. J Altern Complement Med. 2011;17(6):505-512.

Last reviewed December 2015 by EBSCO CAM Review Board  Last Updated: 12/15/2015