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]]>

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 arrythmias (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 arrythmias or treat insomnia or anxiety: Guarana might interfere with their action.