What are the side effects of yerba mate?

October 9, 2025 •

3 min read

While celebrated in South America for centuries, with approximately 70% of pregnant women in a 2005 Brazilian study consuming it daily, excessive yerba mate intake is also associated with significant side effects, ranging from caffeine-induced jitters to long-term health risks.

Quick Summary

Excessive consumption of yerba mate can lead to caffeine-related issues like anxiety, insomnia, and increased heart rate, as well as digestive upset. Concerns exist over increased cancer risk with long-term, high-volume consumption, particularly when brewed very hot.

Key Points

Caffeine-related effects: Excessive consumption can cause insomnia, anxiety, nervousness, increased heart rate, and palpitations.
Long-term cancer risk: Drinking yerba mate at very high temperatures is linked to an increased risk of mouth, esophageal, and other cancers.
Traditional vs. modern drying: Traditional smoke-drying can introduce carcinogenic PAHs; air-dried "green" varieties minimize this risk.
Digestive issues: High doses or sensitivity can lead to stomach upset, nausea, vomiting, and can worsen symptoms of IBS or diarrhea.
Drug interactions: Yerba mate's caffeine can interact with medications for anxiety, depression (MAOIs), diabetes, and blood thinners.
Not recommended for everyone: Individuals who are pregnant, breastfeeding, or have heart conditions, anxiety disorders, or glaucoma should use caution or avoid it.

Yerba mate, an herbal beverage brewed from the leaves and twigs of the Ilex paraguariensis plant, is a cultural staple in several South American countries. It is known for providing an energy boost and a host of antioxidants. However, like coffee and other caffeinated products, it is not without potential downsides, especially when consumed in large quantities or over a long period. Understanding the risks is crucial for safe consumption.

High caffeine content side effects

As a natural stimulant, yerba mate contains caffeine, though the exact amount can vary significantly based on preparation methods. Overconsumption can lead to a range of caffeine-related adverse effects similar to those caused by coffee, although many users report a smoother energy boost without the jitters.

Symptoms of excessive caffeine intake from yerba mate can include:

Insomnia and restlessness: The stimulant effect can disrupt sleep patterns, especially if consumed later in the day.
Anxiety and nervousness: For individuals with sensitivity or existing anxiety disorders, the caffeine can exacerbate symptoms.
Increased heart rate and palpitations: The stimulating effect on the cardiovascular system can cause an irregular or fast heartbeat in some people.
Headaches and dizziness: While sometimes used to treat headaches, overconsumption of caffeine can trigger them.
High blood pressure: Regular caffeine intake can cause a temporary increase in blood pressure.

Digestive discomfort

While traditional use often includes aiding digestion, excessive yerba mate can cause gastrointestinal issues. The caffeine content and other compounds can stimulate bowel movements and irritate the stomach lining.

Stomach upset, nausea, and vomiting: High doses, particularly on an empty stomach, can lead to discomfort.
Diarrhea: The mild diuretic effect of caffeine can worsen or trigger diarrhea.
Worsening of Irritable Bowel Syndrome (IBS): Caffeine can aggravate symptoms for those with IBS.

Cancer risk concerns

One of the most serious and debated risks associated with yerba mate involves a potential link to various cancers, particularly when consumed excessively and very hot. The increased risk is primarily linked to consuming very hot beverages (above 65°C or 149°F), which can damage the throat and esophagus. Some traditional drying methods using smoke can also introduce carcinogenic Polycyclic Aromatic Hydrocarbons (PAHs). The risk may be higher when combined with factors like tobacco or alcohol use. Opting for air-dried varieties can reduce PAH exposure.

Drug interactions

Yerba mate's caffeine content can interact with certain medications. Consult a healthcare provider if taking:

Stimulants and MAOIs: Can cause excessive stimulation or high blood pressure.
Blood thinners: May increase bleeding risk.
Medications for diabetes: Can affect blood sugar levels.
Benzodiazepines: May reduce sedative effects.
Certain antibiotics: Can increase caffeine levels and side effects.

Risks for specific populations

Certain individuals should be cautious:

Pregnant and breastfeeding women: High caffeine is linked to adverse outcomes; caffeine passes into breast milk.
Children: Not recommended.
Individuals with heart conditions: Caffeine can cause irregular heartbeats.
Glaucoma patients: Caffeine can temporarily increase eye pressure.
People with osteoporosis: High caffeine may increase calcium loss.

Yerba mate vs. coffee side effects

Differences exist due to varying chemical compositions.


Feature	Yerba Mate	Coffee
Energy Release	Often smoother, more sustained; fewer jitters reported.	Tends to be quicker, more intense; potential for a crash.
Caffeine Content	Varies widely; generally less than coffee per serving, especially re-brewed.	Typically higher caffeine per serving; also variable.
Stomach Acidity	Generally less acidic; may be gentler on the stomach.	Can be highly acidic; common cause of upset/heartburn.
Cancer Risk	Potential link to esophageal cancer from very hot temperature; some traditional types contain PAHs.	No link from the beverage itself, but the hot temperature risk applies.

Conclusion

While many enjoy yerba mate, awareness of its side effects is vital. Excessive intake can cause caffeine-related issues and digestive upset. Consuming it very hot poses a cancer risk, and some varieties contain PAHs. Pregnant or breastfeeding individuals, children, and those with heart conditions, anxiety, or glaucoma should be cautious or avoid it. Moderation is key, and consulting a healthcare provider is advised, particularly for long-term use or existing health concerns. You can find more information on the National Institutes of Health website.

Frequently Asked Questions

Yes, yerba mate contains caffeine, and excessive intake can cause anxiety, nervousness, and restlessness, especially in individuals with existing anxiety disorders.

Long-term, high-volume consumption of yerba mate, particularly when brewed and consumed very hot (above 65°C), is associated with an increased risk of several types of cancer, including esophageal cancer. Smoke-dried leaves may also contain carcinogenic PAHs.

While traditionally believed to aid digestion, high consumption of yerba mate can cause digestive upset, nausea, vomiting, or diarrhea due to its caffeine content, especially for those with sensitive stomachs or IBS.

Yerba mate is considered possibly unsafe during pregnancy and breastfeeding due to its high caffeine content, which has been linked to miscarriage and low birth weight in high doses. It is best to avoid it or consult a doctor for a safe daily limit.

Yerba mate often provides a smoother, more sustained energy boost with fewer jitters than coffee, but its side effects are still largely caffeine-driven. Unlike coffee, traditional yerba mate carries the additional risk related to consuming very hot liquids.

Yes, the caffeine in yerba mate can interact with various medications, including blood thinners, certain antibiotics, and drugs for depression or diabetes. It can affect clotting, medication metabolism, and blood sugar levels.

Yes, air-dried or "green" yerba mate varieties, which do not undergo smoke-drying, are likely to contain lower levels of PAHs, reducing one of the potential risk factors associated with traditional smoke-dried mate.