Guarana is a weed native to the Amazon basin, particularly Brazil. The seeds of the plant may be harvested to compound natural medicines and energy products.
We make no therapeutic claims for any product not listed with the TGA. This information is to provide history for educational purposes only. Use only on the advice of a registered health professional such as a Doctor, Pharmacist, Naturopath, Herbalist, or other.
Guarana was primarily used for enhancing mood, increasing alertness, cognitive function, and appetite suppression. Other reported traditional applications include libido enhancement and protection from malaria. (Ref 1)
The main active ingredient in Guarana seeds is caffeine, containing 3-6% on a dry weight basis. However Clinical studies suggest that Guarana's effects on cognitive function are due to more than it's caffeine content. It has also been suggested that Guarana's effects are longer lasting than caffeine, possibly due to the saponin and tannin content. (Ref 1)
In a study using doses of 37.5mg, 75mg, 150mg and 300mg, all doses improved picture and word recognition, improved alertness, and reduced headache. The two lower doses produced better results than the two higher doses, which were associated with impaired accuracy of choice reactions and subtraction tests. Observations suggest effects were not due to caffeine alone as effects were still present after six hours, and better results were obtained with 37.5mg as opposed to 300mg with a caffeine content of less than 5mg in the lowest dose. All doses improved mood, however peak cognitive improvement was seen with the 75mg dose. (Ref 1)
Another study compared 75mg of Guarana with 200mg of Ginseng (Panax). Guarana was superior to Ginseng in improving speed of performance, and showed comparable improvement in task performance. (Ref 1)
A dose of 50mg of Guarana per day produced a significant reduction in chemotherapy related fatigue compared to placebo and was not associated with toxicity or adverse effects. (Ref 1)
Standardized extracts, tinctures, and solid formulations prepared by a health professional may provide more reliable dosage, however there is no guarantee of strength, purity, or safety of herbal medications, so effects can vary. As with any medicinal preparation, to ensure the correct dose, patients have been encouraged to measure all liquid medications with an appropriate device such as a dropper, measuring spoon, or cup.
Using different formulations of Guarana together greatly increases risk of an overdose.
The appropriate dosage of Guarana depends on several factors such as the patient's age, health, and other medical conditions. Keep in mind that natural products are not always necessarily safe. Be sure to follow relevant directions on product labels and consult your pharmacist or physician before taking.
Guarana seed powder: Doses between 37.5mg and 75mg are sufficient to provide improvement in mood, alertness and cognition for at least six hours. However doses up to 300mg have also been used regularly. Daily dosage should not exceed a total of 250mg of caffeine per day. This is equivalent to 2.5-4g of Guarana seed powder per day, depending on actual caffeine content. (Ref 1)
Guarana Capsules 500mg: One or two capsules up to every six hours maximum. (Ref 1)
Guarana 40mg and Siberian Ginseng 260mg capsules: Two capsules every six hours as a cognitive enhancer for work or study. Do not exceed six weeks treatment with at least two weeks break. (Ref 1)
Side effects -
Based on caffeine content, the following adverse effects may theoretically occur at high doses: Agitation, tremor, anxiety, restlessness, headache, hypertension, tachycardia, diarrhoea, GI cramping, nausea, diuresis. (Ref 1)
Animal tests have shown an absence of toxicity at high doses up to 1-2g per kg. (Ref 1)
Other medical conditions -
Use with caution in people with hypertension, anxiety states, gastric ulcers, diabetes, and some cardiovascular diseases.
Do not use if pregnant or breastfeeding due to high caffeine content
Drug interactions - Controlled studies are not available therefore listed interactions are theoretical.
CNS Stimulants: Additive stimulant activity.
CNS sedatives: Some antagonistic activity.
Diuretics: Additive effect, use with caution.
Anticoagulants and antiplatelets: increased bleeding in theory. Monitor.
Digoxin: Lowering of blood potassium may reduce threshold for Digoxin toxicity. Avoid long term high dosing.
1) Herbs and Natural supplements, an evidence based guide, volume 2, 4th edition. Braun and Cohen 2015. p532-537.