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Reviewed by the Scan Dose Research Team and Clinical Advisory Board

Guarana

MODERATE EVIDENCESupplementLast updated April 2026

SCAN DOSE SUMMARY

Guarana is a Brazilian plant seed that contains 2-7% caffeine — about 2-3x the concentration of coffee beans. Our research shows its effects are primarily caffeine-mediated, though guarana's tannin content slows caffeine release, producing a more gradual stimulant effect. It's essentially a slow-release caffeine source with some additional polyphenol benefits. All caffeine interactions apply.

EVIDENCE GRADES

Alertness / cognitive performanceAttributed to caffeine content
B
Fat oxidationCaffeine-mediated
C+
Exercise performanceCaffeine-mediated
C+
Weight loss (energy drinks)Minimal independent effect beyond caffeine
C

OPTIMAL DOSAGE

  • Standard: 50-200mg guarana extract (delivering 10-80mg caffeine)
  • As caffeine source: Calculate caffeine content (typically 40-50% by weight in standardized extracts)
  • Sum total daily caffeine from ALL sources including guarana
Scan a supplement containing Guarana

DRUG INTERACTIONS

Adenosine (cardiac drug)Severe

Caffeine antagonizes adenosine

MAO inhibitorsSevere

Enhanced cardiovascular/CNS effects

LithiumSevere

Caffeine increases lithium excretion

Stimulants (Adderall)Moderate

Additive stimulation

Fluoroquinolones (cipro)Moderate

CYP1A2 inhibition increases caffeine levels

SAFETY PROFILE

Drug Interactions

All caffeine interactions apply (see Caffeine monograph). Key ones:

Side Effects

  • Same as caffeine: insomnia, anxiety, tachycardia, GI upset at high doses
  • Tannin content may cause GI irritation in sensitive individuals

Pregnancy & Lactation

  • Same guidelines as caffeine: limit to 200mg caffeine/day total during pregnancy.

WADA Status

Not Prohibited (but caffeine monitoring threshold applies)

HOW SCAN DOSE SCORES THIS

Dose AI calculates caffeine contribution from guarana and sums with all other caffeine sources
Products using guarana to hide total caffeine content: flag ("guarana 500mg" may contain 200mg+ caffeine)
Energy drink / fat burner products: require total caffeine calculation across all ingredients
Products listing guarana without disclosing caffeine content: automatic transparency flag

CLINICAL REFERENCES

1.

Haskell CF et al. A double-blind, placebo-controlled study evaluating the cognitive and mood effects of guarana.

PMID: 16168634

2.

Kennedy DO et al. Improved cognitive performance in human volunteers following administration of guarana.

PMID: 17685131

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Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated: April 2026

Not medical advice. Based on published clinical research and systematic reviews.

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