Is Guayusa Safe? Side Effects, Pregnancy and Who Should Skip It

Guayusa has been brewed in the Ecuadorian Amazon for generations, and today it's showing up in mugs across the U.S. as a coffee alternative. So it's a fair question: is guayusa safe?

For most healthy adults, guayusa is an everyday caffeinated tea, and its safety questions are mostly caffeine questions. That's good news, because caffeine is one of the most studied substances in the world. Below we cover what the research says about guayusa itself, the side effects caffeine can cause, and the people who should limit it or talk to a doctor first.

This article is general information, not medical advice. If you have a health condition, are pregnant or breastfeeding, or take medication, please talk to your doctor.

What Research Says About Guayusa Itself

Guayusa (Ilex guayusa) is a holly, a cousin of yerba mate. A 2019 scientific review of its composition and history of use concluded that guayusa's known chemistry appears to present no greater risk than green tea or yerba mate. The authors also looked at three years of hospital, poison-center and food-safety data in Ecuador, where guayusa is widely consumed, and found only one call-center report of a mild, self-resolving reaction (hyperactivity and insomnia).

Toxicology testing points the same way. In a 2016 study of a standardized guayusa concentrate, the product was negative in standard genetic-toxicity tests, and in a 90-day rat study its effects matched those of the same amount of caffeine given alone, with no extra toxicity from guayusa's other components.

The first human trial on guayusa extract (University of Iowa, 2024) found what you'd expect from a caffeinated product: blood pressure rose by about 4–5 mmHg at both doses tested, heart rhythm measures (QTc) didn't change, and the higher dose made some women feel more jittery. That study used concentrated extract, much stronger than a cup of tea.

The same review is honest about the gaps: guayusa's chemistry is less studied than that of tea or coffee, and more research is needed. In other words, guayusa looks like a familiar kind of drink, a caffeinated leaf, and the main thing to manage is how much caffeine you take in.

Is guayusa psychoactive?

No, not in the way the question usually means. Guayusa is a caffeinated holly. It is not related to ayahuasca, and researchers analyzing guayusa found caffeine, not hallucinogenic compounds, behind its stimulant effect. It wakes you up the way tea or coffee does.

Possible Side Effects (They're Caffeine Side Effects)

Because guayusa contains caffeine, too much of it can cause the same side effects as too much coffee. MedlinePlus (from the U.S. National Library of Medicine) and the FDA list effects such as:

• Trouble sleeping, especially if you drink it in the afternoon or evening
• Restlessness, jitters or anxiety
• Faster heart rate or palpitations
• Headaches or dizziness
• Upset stomach or nausea for some people (caffeine can increase stomach acid)

MedlinePlus notes that caffeine's effects peak within about an hour and can last four to six hours. If you drink guayusa late in the day and sleep poorly, try moving your last cup earlier. A small study with coffee found that caffeine in the evening shortened sleep, lowered its quality and reduced the body's nighttime melatonin, the hormone that helps time sleep. There's no reason to expect caffeine from a leaf to behave differently.

Regular caffeine drinkers who stop suddenly can also get withdrawal symptoms like headaches, tiredness and irritability. These usually pass within a few days.

Many drinkers describe guayusa's lift as smoother than coffee, but everyone responds to caffeine differently. If you notice any of the effects above, cut back.

How Much Is Too Much?

According to the FDA, 400 mg of caffeine a day is an amount not generally associated with negative effects in healthy adults. The European Food Safety Authority (EFSA) reached a similar figure in its 2015 review. Some people are more sensitive and do better with less.

The key is counting your total from all sources: guayusa, coffee, soda, energy drinks and chocolate. For a deeper look, see How Much Caffeine Is in Guayusa?

Caffeine in each PACHA format

Here are the approximate figures from our product information:

For comparison, the FDA puts a 12 oz cup of brewed coffee at about 113–247 mg, black tea at about 71 mg and green tea at about 37 mg. Steeping longer or using more leaf makes a stronger cup, so treat these numbers as a guide.

Who Should Be Careful (or Skip It)

Pregnancy

ACOG (the American College of Obstetricians and Gynecologists) says moderate caffeine intake, less than 200 mg per day, does not appear to cause miscarriage or preterm birth. That's a total from all sources. For example, one teaspoon of guayusa powder (~120 mg) plus a cup of coffee could already pass that line.

Newer research suggests extra caution. A 2021 study from the U.S. National Institutes of Health, following more than 2,000 pregnant women, linked even about 50 mg of caffeine a day (roughly half a cup of coffee) to babies who were slightly smaller at birth. The researchers suggested it may be prudent to limit or skip caffeinated drinks during pregnancy until more is known.

If you're pregnant or trying to conceive, talk to your doctor or midwife before adding guayusa to your routine. Lower-caffeine options like a single green tea bag are easier to fit under the limit, but your care team should set your number.

Breastfeeding

MedlinePlus notes that caffeine passes into breast milk. If you're breastfeeding, ask your doctor or your baby's pediatrician how much caffeine, if any, is right for you.

Children and teens

Guayusa isn't a kids' drink. MedlinePlus says children and teens shouldn't have as much caffeine as adults and can be especially sensitive to it, and U.S. dietary guidance advises no caffeinated drinks for children under 2.

Medications and health conditions

Caffeine can interact with some medications, including stimulants, certain antibiotics, asthma medicines and heart medicines, according to MedlinePlus. People with sleep disorders, migraines, anxiety, acid reflux (GERD), ulcers, irregular heartbeat or high blood pressure should also ask their doctor about caffeine. If any of these apply to you, check with your doctor or pharmacist before drinking guayusa regularly.

So, Is Guayusa Good for You or Bad for You?

Neither label quite fits. Guayusa is a naturally caffeinated leaf with a long history of everyday use, and a scientific review found no signs that it's riskier than tea or yerba mate. It isn't a medicine, and it isn't proven to treat or prevent anything. Whether it's a good fit for you mostly comes down to caffeine: how much you take in, when, and how your body responds.

If you'd like to start gently:

• Green Guayusa Tea Bags (100 ct) have the lowest caffeine per bag in our range, about 22 mg.
• Golden Guayusa Loose Leaf is the gentlest of our three loose-leaf varieties by lab figure, about 52 mg per 4 g serving, with a smooth, mellow flavor.

New to the leaf? Read What Is Guayusa?, or see what's inside in Guayusa Tea Benefits. When you're ready, a box of Green Guayusa Tea Bags is an easy, low-caffeine way to see how guayusa fits your day.

Frequently Asked Questions

Is guayusa safe to drink every day?

For most healthy adults, a daily cup of guayusa fits within normal caffeine guidelines. The FDA says up to 400 mg of caffeine a day is not generally associated with negative effects in healthy adults. A 4 g serving of our loose leaf has about 52–66 mg. Count all your caffeine sources, and talk to your doctor if you're pregnant, take medication or have a heart condition.

What are the side effects of guayusa?

Guayusa's side effects come from its caffeine. Too much can cause trouble sleeping, restlessness, a faster heart rate, headaches, or an upset stomach in some people. A 2019 scientific review found no greater risk from guayusa than from green tea or yerba mate. If you notice side effects, drink less, choose a lower-caffeine format, or have your last cup earlier in the day.

Can I drink guayusa while pregnant?

Guayusa contains caffeine, so it counts toward your daily total. ACOG advises keeping caffeine under 200 mg per day during pregnancy. A single green guayusa tea bag has about 22 mg, while a teaspoon of guayusa powder has about 120 mg. A 2021 NIH study linked even small daily amounts to slightly smaller babies, and its authors suggested limiting caffeine even more. Please talk to your doctor or midwife before drinking guayusa during pregnancy, and let them guide how much is right for you.

Is guayusa psychoactive or related to ayahuasca?

No. Guayusa is a caffeinated holly tree, a relative of yerba mate, and it's not related to ayahuasca. Scientific analyses attribute its stimulant effect to caffeine rather than any hallucinogenic compound. It wakes you up much like coffee or tea does. In Ecuador it's an everyday family drink, often shared in the early morning before work.

Can kids drink guayusa?

We don't recommend guayusa for children. It contains caffeine, and MedlinePlus notes that children and teens can be especially sensitive to caffeine and shouldn't have as much as adults. U.S. dietary guidance advises no caffeinated drinks for children under 2. For teens, talk to your pediatrician about whether any caffeine is appropriate.

Does guayusa interact with medications?

Research on guayusa-specific drug interactions is limited, but its caffeine can interact with some medications, including stimulants, certain antibiotics, asthma medicines and heart medicines, according to MedlinePlus. If you take any prescription medication or have a heart condition, high blood pressure or anxiety, ask your doctor or pharmacist before drinking guayusa regularly.