How does Guarana work?

Guarana contains caffeine. Caffeine works by stimulating the central nervous system (CNS), heart, and muscles. Guarana also contains theophylline and theobromine, which are chemicals similar to caffeine.

Are there safety concerns?

Guarana is safe for most adults. The caffeine in guarana can cause insomnia, nervousness and restlessness, stomach irritation, nausea, vomiting, increased heart rate and blood pressure, rapid breathing, tremors, delirium, diuresis, and other side effects. Large guarana doses might cause headache, anxiety, agitation, ringing in the ears, pain when urinating, stomach cramps, and irregular heartbeats. People who take guarana regularly may experience caffeine withdrawal symptoms if they reduce their usual amount.

If you are pregnant or breast-feeding, guarana should be taken with caution due to the caffeine content. Small amounts are probably not harmful; however, consuming more than 200 mg/day has been linked to an increased risk of miscarriage and other negative effects.

Avoid consuming large amounts of guarana if:
  • You are pregnant or breast-feeding. Large amounts of guarana might not be safe.
  • You have a heart condition.
  • You have high blood pressure.
  • You have anxiety.
  • You have an eye disease called glaucoma.
  • You have osteoporosis.
  • You have a bleeding condition.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.