Herbal Monograph
Guaraná
Paullinia cupana Kunth
Sapindaceae (Soapberry family)
Amazon's premier cognitive stimulant — the world's richest natural caffeine source with sustained-release polyphenol matrix for alert, focused energy.
Overview
Plant Description
Large, woody, evergreen climbing vine (liana) reaching 10-12 m in length, climbing by tendrils on supporting trees in the forest understory and canopy. Stems are woody, cylindrical, with smooth grayish-brown bark. Leaves are alternate, pinnately compound with 5 leaflets; leaflets are oblong-ovate, 8-15 cm long, with serrate margins, glossy dark green above, paler below. Flowers are small, white or yellowish, borne in axillary racemes or panicles. Fruit is a three-valved capsule, 1-2 cm diameter, that splits open when ripe to reveal 1-3 glossy dark brown to black seeds partially covered by a fleshy white aril — the exposed seed within the bright red-orange capsule strikingly resembles a human eye, which features prominently in indigenous Sateré-Mawé mythology about the plant's origin. Seeds are the primary medicinal and commercial part: hard, ovoid, about the size of a coffee bean, rich brown, with a thin seed coat.
Habitat
Tropical rainforest of the Amazon basin. Native to the understory of terra firme (non-flooded upland) forests, climbing on tall trees at the forest edge or along waterways where light penetrates the canopy. Thrives in hot, humid tropical climates with abundant rainfall (1,500-3,000 mm/year), temperatures of 23-28°C year-round, and rich, well-drained lateritic soils.
Distribution
Native to the central Amazon basin of Brazil, with the center of genetic diversity in the lower Amazon region (Maués, Amazonas state). Also found wild in Venezuela and Colombia. Commercially cultivated primarily in Bahia state and Amazonas state, Brazil. Brazil is the dominant global producer; guarana is culturally and economically central to the Maués region. Small-scale cultivation in other tropical countries but production remains overwhelmingly Brazilian.
Parts Used
Seed (roasted and powdered)
Preferred: Roasted seed powder (capsules, tablets); standardized extract (typically standardized to caffeine content); traditional bastão (grated into water)
The roasted, dried seed is the primary (and essentially only) medicinal and commercial part. The seed contains the highest concentration of caffeine of any known plant (2-7.5% by dry weight, compared to 1-2% in coffee beans). The roasting process develops flavor compounds and may modify the availability of some constituents. Seed powder is the basis of all guarana products: supplements, energy drinks, and the traditional Amazonian beverage.
Key Constituents
Methylxanthines (purine alkaloids)
The methylxanthines, overwhelmingly dominated by caffeine, are the principal bioactive constituents of guarana and the basis for virtually all its documented pharmacological effects. Caffeine's mechanism of action as an adenosine receptor antagonist is one of the best-characterized drug mechanisms in pharmacology. The effects are dose-dependent: 50-200 mg caffeine produces enhanced alertness, improved concentration, and reduced fatigue; 200-400 mg produces marked stimulation; above 500 mg, anxiety, tremor, and adverse effects become increasingly likely. One important observation from comparative studies: guarana appears to produce more sustained stimulation with less jitteriness than equivalent doses of caffeine from coffee, which may be attributable to the slow release of caffeine from the tannin matrix of the seed (tannins complex with caffeine, slowing GI absorption).
Tannins
The high tannin content (total polyphenols 10-25% of dried seed) is clinically significant for two reasons. First, the catechins and proanthocyanidins are potent antioxidants that may contribute health benefits independent of caffeine — including cardiovascular protection, anti-inflammatory effects, and potentially neuroprotective activity. Second, the physical complexation of tannins with caffeine in the whole seed matrix modulates caffeine pharmacokinetics: caffeine bound to tannins is released more gradually during digestion than free caffeine, potentially explaining the traditional observation that guarana provides a smoother, more sustained energy compared to coffee. This tannin-caffeine interaction is lost in highly purified caffeine extracts but preserved in whole seed powder preparations.
Saponins
The saponin fraction is a minor component of guarana seed. Some preclinical research suggests saponins may contribute to anti-inflammatory and adaptogenic properties, but at the concentrations present in guarana, their clinical significance is likely minimal compared to the methylxanthine and tannin fractions.
Other constituents
The non-methylxanthine, non-tannin constituents are primarily nutritional/structural components of the seed and do not significantly contribute to the pharmacological effects at normal doses.
Herbal Actions
Enhances cognitive function, memory, and mental performance
Guarana enhances cognitive function including attention, alertness, reaction time, working memory, and information processing speed. The cognitive-enhancing effects are primarily mediated by caffeine's antagonism of adenosine A1 and A2A receptors in the cortex and hippocampus, resulting in increased cholinergic, dopaminergic, and glutamatergic neurotransmission. Kennedy et al. (2004) demonstrated that guarana extract improved cognitive performance and mood in young healthy adults at doses as low as 37.5 mg (containing approximately 4-5 mg caffeine), suggesting that non-caffeine constituents (catechins, saponins) may contribute to cognitive effects. Scholey et al. (2013) found that a multivitamin-guarana combination improved cognitive performance and reduced mental fatigue during demanding tasks. The nootropic effect is arguably the best-supported therapeutic action of guarana.
[2, 3, 4]Prevents or slows oxidative damage to cells
Guarana seed has exceptionally high antioxidant capacity due to its concentrated polyphenol profile (catechins, epicatechin, proanthocyanidins). In vitro ORAC (Oxygen Radical Absorbance Capacity) values for guarana seed extract are among the highest reported for plant materials — comparable to or exceeding green tea and cacao. The antioxidant activity is independent of the caffeine content and is attributed primarily to the catechin and proanthocyanidin fractions. Guarana seed extract has demonstrated inhibition of lipid peroxidation, scavenging of superoxide and hydroxyl radicals, and protection of LDL cholesterol from oxidation in vitro.
[2, 6]Reduces inflammation
Anti-inflammatory activity demonstrated in preclinical models, attributed to the polyphenol/tannin fraction rather than caffeine. Guarana seed extract has shown inhibition of NF-kB activation, reduction of pro-inflammatory cytokines (TNF-alpha, IL-1beta, IL-6), and inhibition of COX-2 expression in cell culture and animal models. A population-based study in elderly Amazonian residents (Krewer et al.) found that habitual guarana consumers had lower levels of oxidative stress markers and inflammatory mediators compared to non-consumers.
[6]Tightens and tones tissue, reduces secretions
The high tannin content (10-25% polyphenols) confers significant astringent activity. This is relevant internally for GI complaints (diarrhea, dyspepsia) and externally in topical applications (less commonly used). The astringent action also contributes to the caffeine-modulating 'sustained release' effect discussed under constituents.
[5]Relieves pain
Mild analgesic effect, primarily mediated through caffeine's known mechanism of vasoconstriction of cerebral blood vessels (relevant to headache) and potentiation of other analgesics. Caffeine is an established analgesic adjuvant used in pharmaceutical headache preparations (e.g., Excedrin, Anacin). Guarana-containing analgesic preparations have traditional use in Brazil for headache.
[5]Increases urine production and output
Mild diuretic effect attributable to caffeine and to a lesser extent theobromine. Caffeine increases glomerular filtration rate and inhibits sodium reabsorption in the renal tubules. The diuretic effect is modest at typical guarana doses and is subject to tolerance with chronic use (habitual caffeine consumers develop reduced diuretic response). Not a primary therapeutic use.
[5]Therapeutic Indications
Nervous System
Mental fatigue and cognitive enhancement
The best-supported indication for guarana. Kennedy et al. (2004) demonstrated improved cognitive performance (secondary memory, speed of attention) with guarana extract at doses containing as little as 4-5 mg caffeine, suggesting synergistic effects of non-caffeine constituents. Haskell et al. (2007) showed that guarana improved alertness, contentment, and memory performance in young adults. The effects on attention and processing speed are well-established through the extensive caffeine literature (>100 RCTs on caffeine and cognition), and guarana-specific studies corroborate these effects with the added observation of potentially more sustained and smoother stimulation due to the tannin-caffeine matrix.
[2, 3, 4]Physical fatigue and exercise performance
Caffeine is one of the most well-documented ergogenic (performance-enhancing) substances in exercise science, with meta-analyses confirming improvements in endurance, strength, and time-to-exhaustion. Guarana, as a concentrated caffeine source, provides these benefits. Specific guarana studies on exercise are limited, but the caffeine dose-response relationship is well-established: 3-6 mg/kg body weight of caffeine, taken 30-60 minutes before exercise, improves performance across modalities. The additional polyphenol content of guarana may provide antioxidant protection against exercise-induced oxidative stress.
[2]Headache (tension-type and migraine)
Caffeine is an established analgesic adjuvant with particular efficacy in headache. It produces cerebral vasoconstriction (counteracting the vasodilation associated with migraine), enhances analgesic drug absorption, and has intrinsic analgesic activity through adenosine receptor blockade. Guarana has traditional use in Brazil for headache. The evidence base is primarily the caffeine literature rather than guarana-specific studies. Note: caffeine withdrawal itself causes headache, creating a rebound cycle with chronic use.
[5]Cardiovascular System
Oxidative stress and cardiovascular risk markers
Epidemiological and preliminary clinical data from Amazonian populations suggest that habitual guarana consumption is associated with lower oxidative stress markers, lower LDL oxidation, and potentially favorable lipid profiles. A cross-sectional study in elderly Amazonian residents found that habitual guarana consumers had lower body fat and lower prevalence of metabolic syndrome compared to non-consumers. These observational findings are intriguing but cannot establish causality due to confounding factors (lifestyle, diet, socioeconomic status).
[6]Digestive System
Dyspepsia and sluggish digestion
Traditional Amazonian use includes guarana as a digestive stimulant. Caffeine stimulates gastric acid secretion and GI motility. The astringent tannin fraction may help with loose stools and excessive intestinal secretion. Used traditionally for both appetite stimulation and for managing diarrhea — the caffeine promotes motility while the tannins have an anti-diarrheal effect, suggesting different components address different GI complaints.
[5]Endocrine System
Weight management support (thermogenic/appetite modulation)
Caffeine is a documented thermogenic agent that increases basal metabolic rate (approximately 3-11% increase, dose-dependent) and promotes lipolysis through catecholamine release and phosphodiesterase inhibition. Guarana is a common ingredient in weight management and thermogenic supplements. Epidemiological data from Amazonian populations suggest lower body mass in habitual guarana consumers. However, long-term controlled studies specifically on guarana for weight loss are lacking, and any thermogenic effect is subject to tolerance with chronic use. Guarana-ephedra combinations were historically marketed for weight loss but ephedra has been banned due to cardiovascular risks — guarana should not be combined with sympathomimetic stimulants.
[2]Energetics
Temperature
warm
Moisture
slightly dry
Taste
Tissue States
cold/depression, damp/stagnation
In Western energetic terms, guarana is warming and slightly drying — it stimulates metabolic activity, increases circulation, promotes alertness, and counters the cold/depressed tissue state characterized by fatigue, mental fog, slow metabolism, and lassitude. The bitter taste reflects the alkaloid (methylxanthine) fraction; the astringent taste reflects the high tannin content. Guarana is specifically suited for cold, sluggish, understimulated states and should be used cautiously in individuals with hot, overstimulated, or anxious constitutions, in whom the warming stimulant action could exacerbate agitation, insomnia, and nervous tension. The traditional Amazonian use in hot, humid conditions reflects its value as a circulatory and metabolic stimulant rather than a warming remedy per se — in that context, it addresses lethargy, appetite suppression, and the fatigue of tropical labor.
Traditional Uses
Sateré-Mawé indigenous medicine (Central Amazon)
- Preparation of çapó: guarana bastão grated into a gourd of water using a dried pirarucu fish tongue — the sacred daily beverage of the Sateré-Mawé people
- Endurance and fatigue resistance during long hunting and fishing expeditions
- Treatment of headache and body pain
- Diarrhea and intestinal complaints (astringent action)
- Appetite regulation during periods of food scarcity
- Febrifuge (fever reduction)
- Sacred and cultural significance: the Sateré-Mawé origin myth describes guarana arising from the eye of a divine child, reflected in the seed's eye-like appearance when exposed in the ripe capsule
"The Sateré-Mawé people of the lower Amazon (Maués region, Amazonas state) are the original cultivators and cultural custodians of guarana. Their relationship with the plant is central to their cultural identity and extends back centuries before European contact. The traditional preparation involves roasting seeds, grinding them with water, and forming bastões — hard cylindrical sticks that are smoke-dried and can be stored for months. The bastão is grated into water as needed using a pirarucu tongue rasp. This preparation method is the foundation of all modern guarana use. The Sateré-Mawé consider guarana a gift from the god Tupana and its cultivation is interwoven with their social, ceremonial, and economic life."
[5]
Brazilian folk medicine (caboclo/mestizo traditions)
- General stimulant and tonic for fatigue and lethargy
- Headache remedy (guarana powder in water)
- Treatment of diarrhea and dysentery
- Aphrodisiac and sexual tonic
- Recovery from illness and debility
- Hangover remedy
- Mixed with honey as an energy tonic
"Guarana entered broader Brazilian folk medicine through cultural exchange between indigenous peoples and caboclo (mixed-heritage) Amazonian populations. By the 18th century, guarana was traded throughout Brazil and recognized as a powerful stimulant. Brazilian folk use expanded the indigenous indications to include use as an aphrodisiac, a hangover remedy, and a general health tonic. The guarana-based soft drink industry (Guaraná Antarctica, 1921; Guaraná Jesus) originated from this folk tradition of guarana as a daily health beverage."
[5]
Western herbal medicine (contemporary)
- CNS stimulant for mental and physical fatigue
- Cognitive enhancement and study aid
- Ingredient in energy drinks and thermogenic/weight-loss supplements
- Headache formulas (often combined with willow bark or feverfew)
- Adaptogenic formulas for adrenal fatigue (controversial; guarana is a stimulant, not a true adaptogen)
- Athletic performance enhancement
"Guarana entered Western herbal commerce in the 19th century and has grown into a major global commodity. In modern Western practice, it is used primarily as a natural caffeine source for cognitive and physical performance enhancement. It appears in numerous energy drinks, dietary supplements, and functional foods. Some Western practitioners caution against using guarana as a substitute for addressing underlying causes of fatigue, noting that stimulant herbs mask rather than resolve depletion."
[5]
Modern Research
Cognitive performance — guarana-specific RCTs
Kennedy et al. (2004) conducted a randomized, double-blind, placebo-controlled study evaluating the effects of guarana extract on cognitive performance and mood in young healthy adults.
Findings: Guarana extract at doses of 37.5 mg, 75 mg, 150 mg, and 300 mg (containing approximately 4-5, 9-10, 18-19, and 36-37 mg caffeine, respectively) produced dose-dependent improvements in secondary memory performance and increased speed of attention compared to placebo. Notably, the 37.5 mg dose (lowest caffeine content) produced statistically significant cognitive improvements, suggesting that non-caffeine constituents (catechins, saponins) contribute to the nootropic effect beyond what caffeine alone would produce at that dose. Mood ratings (alertness, contentment) also improved.
Limitations: Single-dose, acute-effects study. Young healthy volunteers (18-30 years); may not generalize to elderly or cognitively impaired populations. Small sample (n=26 per crossover). Effects at very low caffeine doses raise interesting mechanistic questions but require replication. The study used a specific guarana extract; results may vary with different preparations.
[2]
Alertness and mood — cognitive battery study
Haskell et al. (2007) investigated the effects of guarana extract on cognition and mood using a comprehensive cognitive test battery in a double-blind, placebo-controlled, crossover design.
Findings: Guarana extract improved self-rated alertness and contentment, and enhanced performance on attention-demanding cognitive tasks. Effects were evident at doses lower than those that would be expected from the caffeine content alone, consistent with the Kennedy et al. findings suggesting non-caffeine nootropic contributors.
Limitations: Acute single-dose design. Crossover with potential carryover effects despite washout. Healthy young adults only.
[3]
Multivitamin-guarana combination — mental fatigue
Scholey et al. (2013) evaluated a multivitamin-guarana combination for effects on cognitive performance and mental fatigue during extended demanding cognitive tasks.
Findings: The combination including guarana reduced mental fatigue and improved cognitive task performance compared to placebo during sustained demanding cognitive work. The guarana component was considered a key contributor to the fatigue-reducing and performance-maintaining effects observed.
Limitations: Combination product makes it difficult to attribute effects specifically to guarana vs. other ingredients (vitamins, minerals). Design limitations of combination studies apply.
[4]
Antioxidant and lipid effects — Amazonian population study
Cross-sectional and epidemiological studies in elderly Amazonian populations have compared health markers between habitual guarana consumers and non-consumers.
Findings: Habitual guarana consumers (≥ 5 years of regular use) showed significantly lower levels of lipid peroxidation (TBARS), higher total antioxidant capacity, and lower LDL oxidation compared to non-consumers. Some studies also found lower prevalence of hypertension, obesity, and metabolic syndrome in guarana consumers. One study found lower body fat mass and higher lean mass in habitual consumers.
Limitations: Cross-sectional/observational design cannot establish causality. Numerous confounders: guarana consumers in Amazonian communities may differ in diet, physical activity, socioeconomic status, and other lifestyle factors. Healthy user bias is likely (those who consume guarana may be generally more health-conscious). The traditional guarana beverage also differs substantially from commercial energy drinks containing guarana extract.
[6]
Caffeine — extensive meta-analytic evidence (applicable to guarana)
As guarana's primary bioactive is caffeine, the vast caffeine literature (hundreds of RCTs, multiple meta-analyses) is directly applicable.
Findings: Meta-analyses confirm that caffeine at doses of 50-400 mg improves: alertness and reaction time, sustained attention, working and episodic memory, physical exercise performance (endurance, time-to-exhaustion, strength), and provides analgesic adjuvant effects for headache. Caffeine also has documented thermogenic effects (modest increase in metabolic rate and fat oxidation). The extensive caffeine evidence base provides the strongest pharmacological foundation for guarana's clinical applications.
Limitations: Most caffeine research uses pure caffeine or coffee rather than guarana specifically. The additional polyphenol content and the tannin-modulated caffeine release in whole guarana may produce somewhat different effects than pure caffeine. Direct extrapolation requires caution regarding guarana-specific effects.
[2]
Preparations & Dosage
Capsule / Powder
Strength: Crude seed powder, typically 500 mg per capsule. Caffeine content approximately 20-40 mg per 500 mg capsule (varies by seed batch).
Roasted guarana seed powder encapsulated in vegetable or gelatin capsules. Look for products that specify caffeine content per capsule for accurate dosing. Whole seed powder contains the full tannin-caffeine matrix that provides the 'sustained release' effect.
500-2,000 mg of guarana seed powder daily (providing approximately 20-100 mg caffeine, depending on seed caffeine concentration). Start at the lower end and titrate based on individual caffeine sensitivity. For cognitive enhancement: 200-800 mg before demanding mental tasks.
1-2 times daily. Avoid afternoon/evening dosing to prevent sleep disruption. Most effective when taken in the morning or before periods of required mental or physical performance.
Can be used intermittently or regularly. Tolerance to some caffeine effects (diuresis, cardiovascular stimulation) develops with chronic use, but tolerance to cognitive effects is less complete. Periodic breaks (cycling) may help maintain efficacy.
Not recommended for children under 12 due to caffeine content. Adolescents (12-18) should limit total caffeine intake from all sources to < 100 mg/day.
Whole seed powder preserves the tannin-caffeine matrix and provides the full polyphenol profile. This is the preparation form closest to the traditional Amazonian use and may provide more sustained stimulation than isolated caffeine supplements. Calculate caffeine intake from ALL sources (coffee, tea, chocolate, energy drinks, medications) when using guarana to avoid exceeding safe caffeine limits (400 mg/day for healthy adults per FDA guidance).
Standardized Extract
Strength: Varies by product: typically standardized to 10-22% caffeine. Higher-concentration extracts (40-60% caffeine) also exist for energy drink and supplement manufacturing.
Concentrated guarana extract standardized to a specified caffeine percentage. Available in capsule, tablet, or liquid form. Standardization allows precise caffeine dosing.
Depends on standardization. For a 22% caffeine extract: 100-400 mg daily provides 22-88 mg caffeine. For a 10% caffeine extract: 200-800 mg daily. Always dose based on the caffeine content, aiming for 40-200 mg caffeine from guarana per dose depending on individual tolerance and desired effect.
1-2 times daily, morning or early afternoon.
Intermittent or regular use with periodic reassessment.
Not recommended.
Standardized extracts allow precise caffeine dosing but may have reduced polyphenol content compared to whole seed powder, depending on the extraction method. Highly purified extracts with very high caffeine percentages essentially behave like caffeine supplements and lose the 'sustained release' tannin-matrix effect of whole seed preparations. For the full guarana experience including polyphenol benefits, whole seed powder or lower-concentration standardized extracts are preferred.
[2]
Infusion (Tea)
Strength: 1-2 g powder per 250 mL water
Add 1-2 g of guarana seed powder to a cup (250 mL) of hot (not boiling) water. Stir well. The powder does not dissolve completely — it is consumed as a suspension. Alternatively, mix the powder into juice, smoothies, or other beverages. Traditional preparation: grate a guarana bastão into a half gourd of water and stir.
1-2 g powder per serving, 1-2 times daily.
1-2 times daily.
As desired.
Not recommended.
This is closest to the traditional Sateré-Mawé çapó preparation. The taste is bitter and astringent; traditionally sweetened with honey or mixed with fruit. The insoluble seed particles provide the full tannin-caffeine matrix for sustained absorption. Many people find the taste unpleasant and prefer capsules; others appreciate the ritual aspect of preparing the traditional beverage.
[5]
Tincture
Strength: 1:5, 45-55% ethanol
Macerate guarana seed powder in 45-55% ethanol at a ratio of 1:5. Shake daily for 4-6 weeks. Press and filter.
2-4 mL, 1-2 times daily.
1-2 times daily.
As needed.
Not recommended.
Tincture form is less common for guarana than capsules or powder but allows for flexible dosing and combination with other herbal tinctures. The ethanol extracts both caffeine and polyphenols effectively. Not the traditional or most common preparation form.
[5]
Safety & Interactions
Class 2c
Not to be used with specific medications (AHPA Botanical Safety Handbook)
Contraindications
Individuals with known caffeine hypersensitivity (genetic slow metabolizers, CYP1A2 polymorphisms, or functional caffeine intolerance) should avoid guarana. Symptoms of caffeine intolerance include severe anxiety, palpitations, insomnia, or GI distress at low caffeine doses. The high caffeine content of guarana (2-7.5%) means even small amounts can produce significant caffeine exposure.
Caffeine stimulates cardiac conduction and can increase heart rate and trigger or exacerbate supraventricular and ventricular arrhythmias in susceptible individuals. Patients with documented arrhythmias, prolonged QT interval, or other cardiac conduction disorders should avoid guarana and other concentrated caffeine sources.
Caffeine is a well-documented anxiogenic agent at moderate to high doses. It can trigger panic attacks in susceptible individuals and exacerbate generalized anxiety. The DSM-5 recognizes caffeine-induced anxiety disorder as a diagnostic entity. Patients with severe anxiety should avoid guarana or use only at very low doses with awareness of the anxiogenic potential.
Caffeine stimulates gastric acid secretion and relaxes the lower esophageal sphincter. In patients with active peptic ulcers or severe gastroesophageal reflux, guarana may exacerbate symptoms and delay healing.
While moderate caffeine intake (<200 mg/day) is generally considered acceptable during pregnancy, guarana's high caffeine concentration makes accidental overconsumption a risk. Caffeine crosses the placenta readily and fetal caffeine metabolism is immature. High caffeine intake during pregnancy is associated with increased risk of miscarriage and low birth weight. Guarana is classified as Class 2c (not to be used with specific medications) but the AHPA also recommends caution during pregnancy due to caffeine content.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Ephedrine, pseudoephedrine, and sympathomimetic amines (Sympathomimetics / decongestants) | severe | Caffeine and sympathomimetic agents produce additive cardiovascular stimulation: increased heart rate, increased blood pressure, and increased myocardial oxygen demand. Caffeine's phosphodiesterase inhibition increases intracellular cAMP, potentiating sympathomimetic effects. |
| Adenosine (Adenocard) (Antiarrhythmic) | severe | Caffeine is a competitive antagonist at adenosine A1 and A2A receptors. This directly opposes the pharmacological action of intravenous adenosine, which is used therapeutically to terminate paroxysmal supraventricular tachycardia (PSVT) and for pharmacological cardiac stress testing. |
| Lithium (Lithobid, Eskalith) (Mood stabilizers) | moderate | Caffeine increases renal lithium clearance through its diuretic effect, potentially lowering serum lithium levels below the therapeutic range. Conversely, abrupt caffeine withdrawal can increase lithium levels into the toxic range. |
| Clozapine (Clozaril) (Atypical antipsychotics) | moderate | Both caffeine and clozapine are substrates of CYP1A2. Caffeine inhibits CYP1A2, potentially increasing clozapine plasma levels. Conversely, sudden cessation of caffeine can reduce clozapine levels if CYP1A2 activity increases. |
| MAO inhibitors (phenelzine, tranylcypromine, selegiline) (Antidepressants) | moderate | MAO inhibitors can slow caffeine metabolism and enhance the cardiovascular stimulant effects of caffeine through increased catecholamine availability. |
| Fluoroquinolone antibiotics (ciprofloxacin, norfloxacin, enoxacin) (Antibiotics) | moderate | Fluoroquinolones, particularly ciprofloxacin and enoxacin, strongly inhibit CYP1A2, the primary enzyme responsible for caffeine metabolism. This significantly increases caffeine half-life and serum levels (up to 2-5× increase with enoxacin). |
| Fluvoxamine (Luvox) (SSRIs) | moderate | Fluvoxamine is a potent CYP1A2 inhibitor that can dramatically reduce caffeine clearance, increasing caffeine levels and half-life by several-fold. |
| Warfarin (Coumadin) (Anticoagulants) | minor | High-dose caffeine has been reported to have mild antiplatelet effects, and some reports suggest potential effects on warfarin metabolism, though the clinical significance is debated. |
Pregnancy & Lactation
Pregnancy
possibly unsafe
Lactation
possibly unsafe
PREGNANCY: Caffeine crosses the placenta freely and fetal metabolism of caffeine is very slow (half-life up to 100 hours in the neonate). Meta-analyses associate high caffeine intake (>200-300 mg/day) with increased risk of miscarriage and small-for-gestational-age birth. ACOG (American College of Obstetricians and Gynecologists) recommends limiting caffeine to <200 mg/day during pregnancy. Guarana's high caffeine concentration makes accidental overconsumption a risk during pregnancy; if any guarana is used, careful caffeine accounting from all sources is essential. Most practitioners recommend avoiding concentrated caffeine supplements including guarana during pregnancy. LACTATION: Caffeine is excreted into breast milk (approximately 1% of maternal dose). Peak breast milk caffeine levels occur 1-2 hours after maternal ingestion. Infant symptoms of excessive caffeine exposure through breast milk include irritability, poor sleeping, and jitteriness. Moderate maternal caffeine intake (<200-300 mg/day) is generally considered compatible with breastfeeding per LactMed, but concentrated guarana supplements add unnecessary risk. Use caution; prefer low doses if used at all during lactation.
Adverse Effects
References
Monograph Sources
- [1] Gardner Z, McGuffin M (eds.). American Herbal Products Association's Botanical Safety Handbook, Second Edition: Paullinia cupana. CRC Press, Boca Raton (2013)
Clinical Studies
- [2] Kennedy DO, Haskell CF, Wesnes KA, Scholey AB. Improved cognitive performance in human volunteers following administration of guarana (Paullinia cupana) extract: comparison and interaction with Panax ginseng. Pharmacol Biochem Behav (2004) ; 79 : 401-411 . DOI: 10.1016/j.pbb.2004.07.014 . PMID: 15582012
- [3] Haskell CF, Kennedy DO, Wesnes KA, Milne AL, Scholey AB. A double-blind, placebo-controlled, multi-dose evaluation of the acute behavioural effects of guaraná in humans. J Psychopharmacol (2007) ; 21 : 65-70 . DOI: 10.1177/0269881106063815 . PMID: 16533867
- [4] Scholey A, Bauer I, Neale C, Savage K, Camfield D, White D, Pipingas A, Stough C. Acute effects of different multivitamin mineral preparations with and without guaraná on mood, cognitive performance and functional brain activation. Nutrients (2013) ; 5 : 3589-3604 . DOI: 10.3390/nu5093589 . PMID: 24036528
Traditional Texts
- [5] Hoffmann D. Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press, Rochester, VT (2003)
Pharmacopeias & Reviews
- [6] Basile A, Ferrara L, Del Pezzo M, Mele G, Sorbo S, Bassi P, Montesano D. Antibacterial and antioxidant activities of ethanol extract from Paullinia cupana Mart.. J Ethnopharmacol (2005) ; 102 : 32-36 . DOI: 10.1016/j.jep.2005.05.038 . PMID: 16085377
Last updated: 2026-03-23 | Status: published
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