The Guayusa Guide
Is guayusa safe, and does it have side effects?
Guayusa has a long history of use as a tea, and a safety review published in 2020 found that its known composition appears to present no greater risk to health than green tea or yerba mate. Its side effects are those of caffeine: Health Canada names insomnia, irritability, headaches and nervousness. Health Canada recommends a maximum of 400 mg of caffeine a day for adults, and 300 mg for people who are pregnant or who breastfeed.
What are the side effects of guayusa?
Guayusa contains caffeine, so too much guayusa has the effects of too much caffeine. Health Canada says that some of the side effects of caffeine may include insomnia, irritability, headaches and nervousness. If you are sensitive to caffeine, Health Canada suggests that you avoid it or have less.
In a trial published in 2024, a guayusa leaf extract raised blood pressure by 4 to 5 mmHg, and the higher dose made women feel more jittery.
How much caffeine is too much?
| Who | Maximum in a day |
|---|---|
| Adults (18 years and over) | 400 mg |
| People who are pregnant or who plan to become pregnant | 300 mg |
| People who breastfeed | 300 mg |
| Children and adolescents (up to 18 years) | 2.5 mg for each kilogram of body weight |
A 355 mL can of ready-to-drink Waísa has 140 mg of caffeine. Count each source of caffeine in your day: coffee, tea, cola and chocolate also have caffeine. See how much caffeine is in guayusa.
Can you drink guayusa when you are pregnant or when you breastfeed?
Health Canada recommends no more than 300 mg of caffeine a day from all sources for people who are pregnant, who plan to become pregnant or who breastfeed. Health Canada also says that people who are pregnant or who breastfeed should not consume caffeinated energy drinks. The label of a can of Waísa says that it is not recommended for pregnant or breast-feeding women. Speak with your health care provider about the caffeine in your day.
Can children drink guayusa?
Health Canada recommends no more than 2.5 mg of caffeine for each kilogram of body weight a day for children and adolescents, and it says that children should not consume caffeinated energy drinks. The label of a can of Waísa says that it is not recommended for those under 14 years old.
What does the label of a can of Waísa say?
The caution of the label is: “Not recommended for those under 14 years old, pregnant or breast-feeding women or individuals sensitive to caffeine. Do not drink more than 2 servings per day. Do not drink on the same day as any other supplemented foods or supplements with caffeine.”
What do the safety studies of guayusa say?
- A review published in 2020 found that broad consumption of guayusa is not associated with a history of adverse effects. It also says that the knowledge of the chemical profile of guayusa is still new.
- A toxicology study published in 2016 gave rats a guayusa concentrate for 90 days. The effects were comparable to those of the same amount of caffeine, with no sign of added toxicity from other components of guayusa.
- A trial published in 2016 gave 12 men 200 mg of caffeine from a guayusa leaf extract. It found no statistically significant change in blood pressure or heart rate compared with synthetic caffeine.
Common questions
Is guayusa safe during pregnancy?
Health Canada recommends no more than 300 mg of caffeine a day for people who are pregnant, and it says that they should not consume caffeinated energy drinks. The label of a can of Waísa says that it is not recommended for pregnant or breast-feeding women. Speak with your health care provider.
Does guayusa keep you awake?
It can. Guayusa contains caffeine, and Health Canada names insomnia as one of the side effects of caffeine.
How many cans of Waísa can you drink in a day?
The label says not to drink more than 2 servings per day, and not to drink it on the same day as other supplemented foods or supplements with caffeine. Two cans have 280 mg of caffeine. Health Canada recommends a maximum of 400 mg a day for adults.
This page gives general information. It is not medical advice.
Sources
- Health Canada, Caffeine in Foods: the side effects of caffeine and the recommended maximum daily intake.
- Health Canada, Caffeinated energy drinks: who should not consume them, and the cautions of the label.
- Wise G. and Negrin A., A critical review of the composition and history of safe use of guayusa: a stimulant and antioxidant novel food, Critical Reviews in Food Science and Nutrition, 2020.
- Kapp R. W. and others, General and Genetic Toxicology of Guayusa Concentrate (Ilex guayusa), International Journal of Toxicology, 2016.
- Krieger D. R. and others, The Safety, Pharmacokinetics, and Nervous System Effects of Two Natural Sources of Caffeine in Healthy Adult Males, Clinical and Translational Science, 2016.
- Helwig N. J. and others, Acute, dose-response effects of guayusa leaf extract on mood, cognitive and motor-cognitive performance, and blood pressure, heart rate, and ventricular repolarization, Journal of the International Society of Sports Nutrition, 2024.