What are the negative effects of yerba mate?

October 9, 2025 •

3 min read

Some studies suggest that long-term consumption of large quantities of yerba mate may be linked to an increased risk of certain cancers, particularly when consumed very hot. Understanding what are the negative effects of yerba mate is crucial for making informed choices about your health and diet.

Quick Summary

Excessive consumption of yerba mate can lead to caffeine-related side effects like anxiety, insomnia, and palpitations. Long-term, high-volume use has also been linked to an increased risk of specific cancers and can cause potential interactions with various medications.

Key Points

Cancer Risk: Excessive, long-term consumption of yerba mate, especially when hot, is linked to a higher risk of certain cancers, possibly due to PAHs and thermal injury.
Caffeine Overload: The significant caffeine content can cause anxiety, insomnia, heart palpitations, and headaches in sensitive individuals or with high doses.
Medication Interactions: Yerba mate can interfere with numerous prescription drugs, including stimulants, MAOIs, and anticoagulants, leading to adverse effects.
Contraindicated for Some: Pregnant and breastfeeding women, as well as those with heart conditions, anxiety disorders, or diabetes, should exercise caution or avoid yerba mate.
Digestive Issues: Some users may experience stomach upset or worsen IBS symptoms, particularly if consuming large amounts or drinking on an empty stomach.
Liver Health: While rare, there have been case reports linking yerba mate to clinically apparent liver injury.

Yerba mate, a caffeinated herbal drink derived from the Ilex paraguariensis tree, has gained global popularity for its stimulating and purported health benefits. However, like any substance, excessive or improper consumption can lead to negative health consequences. While moderate intake may be safe for most healthy adults, understanding the potential drawbacks is essential.

Potential Link to Certain Cancers

One of the most serious concerns surrounding yerba mate is its potential link to an increased risk of several cancers, especially in high-volume, long-term users. Yerba mate naturally contains polycyclic aromatic hydrocarbons (PAHs), known carcinogens. Traditional drying methods can increase the PAH content. Additionally, drinking very hot yerba mate (149°F or 65°C and hotter) is linked to a higher risk of mouth, throat, and esophageal cancers, possibly due to thermal injury.

Caffeine-Related Side Effects

As a caffeinated beverage, yerba mate can cause similar side effects to coffee when consumed in excess. Caffeine content varies, but high intake from multiple servings can lead to issues.

Common caffeine-related issues include:

Anxiety and nervousness.
Insomnia and sleep disturbances.
Increased heart rate and palpitations, especially for those with heart conditions.
Headaches and upset stomach.

Specific Contraindications and Precautions

Certain individuals should be cautious or avoid yerba mate.

Pregnancy and Breastfeeding

Due to caffeine, yerba mate is potentially unsafe during pregnancy and breastfeeding, with risks including low birth weight and miscarriage. Caffeine and other compounds can pass to infants via breast milk.

Pre-existing Health Conditions

Individuals with anxiety disorders, bleeding disorders, heart conditions, diabetes, Irritable Bowel Syndrome (IBS), or osteoporosis should consult a healthcare provider before use.

Interaction with Medications

Yerba mate can interact with medications, potentially causing adverse effects. It can amplify the effects of stimulant drugs and MAOIs. Caffeine may slow blood clotting, impacting anticoagulants. Interactions with various other medications have also been noted.

Potential for Liver and Digestive Issues

Rare cases of liver injury have been reported with yerba mate consumption. Some individuals may also experience digestive upset, like bloating or irritation, particularly on an empty stomach.

Negative vs. Positive Effects: A Comparison


Aspect	Potential Negative Effects	Potential Positive Effects
Cancer Risk	Increased risk of upper digestive and respiratory cancers, especially with high volume and temperature.	Some studies suggest antioxidant properties may offer protection, but this is outweighed by risks with high consumption.
Caffeine Impact	Anxiety, insomnia, heart palpitations, and headaches with high intake.	Increased energy, improved focus, and mental clarity.
Digestive System	Upset stomach, bloating, or exacerbated IBS symptoms in sensitive individuals.	Can aid digestion in some cases, particularly in a relaxed setting.
Interactions	Interference with various medications, leading to potentially serious side effects.	Few negative interactions for healthy individuals not on contraindicating medications.
Overall Health	Potential long-term risks with chronic, excessive consumption, especially if paired with tobacco or alcohol.	High in antioxidants, vitamins, and minerals that support overall health.

Conclusion: Moderation is Key

The potential negative effects of yerba mate are linked to consumption amount, preparation, and individual health. While moderate intake is likely safe, high-volume, long-term use poses greater risks, particularly for certain cancers and caffeine-related issues. Individuals with health conditions, pregnant women, and those on specific medications should be cautious. Enjoying yerba mate moderately and at a reasonable temperature is advisable.

For more detailed information on yerba mate and health risks, a resource like this LiverTox entry is recommended: Yerba Mate - LiverTox - NCBI Bookshelf.

Frequently Asked Questions

Studies suggest that long-term, excessive consumption of yerba mate, especially when consumed very hot, is associated with a higher risk of certain cancers, such as oral, throat, and esophageal. The presence of polycyclic aromatic hydrocarbons (PAHs) and the thermal injury from hot liquids are contributing factors.

Since yerba mate contains caffeine, it can cause similar side effects to coffee, including anxiety, insomnia, increased heart rate, and upset stomach, particularly when consumed in large amounts. However, some users report a more balanced energy lift due to other compounds in the tea.

Yerba mate is considered possibly unsafe during pregnancy and breastfeeding due to its caffeine content. High caffeine intake can increase the risk of miscarriage or low birth weight, and the caffeine can pass to the infant through breast milk.

Yes, some people may experience digestive issues, such as stomach upset, bloating, or diarrhea, especially if they are sensitive to caffeine or consume it on an empty stomach. Individuals with IBS should be particularly cautious.

Yerba mate can interact with many medications, including stimulants, certain antidepressants (MAOIs), blood-thinning medications, and some antibiotics. It is crucial to consult a doctor if you are on any medication before consuming yerba mate.

Drinking 1-2 liters (about 4-8 cups) of yerba mate daily over a long period is considered high consumption and is linked to greater risks. For most adults, moderate intake is recommended, and the threshold can vary by individual sensitivity to caffeine.

Due to its caffeine content, yerba mate can increase heart rate and potentially cause irregular heartbeats in some individuals. Those with pre-existing heart conditions should use caution and consult a healthcare provider.

Drinking yerba mate at very high temperatures (over 65°C or 149°F) is associated with a higher risk of upper digestive tract cancers. The repeated thermal injury to the mucosal lining is a suspected cause.