Does Matcha Have Any Negative Effects? A Deep Dive

October 22, 2025 •

4 min read

Matcha is prized for its high antioxidant content and calming energy, but a serving can contain up to 70mg of caffeine, potentially causing issues for those with sensitivities. Beyond caffeine, questions about contaminants and other side effects are common. So, does matcha have any negative effects? Here's what you need to know to consume it safely.

Quick Summary

This article explains the potential side effects of matcha, including caffeine-related symptoms, digestive problems, and the risk of heavy metal contamination in low-quality products. It details who should be cautious and how to mitigate risks by choosing ceremonial-grade matcha and moderating intake.

Key Points

Caffeine Sensitivity: Excess matcha can lead to jitters, anxiety, and insomnia in those sensitive to stimulants, though the L-theanine helps moderate these effects.
Digestive Issues: Tannins and catechins in matcha can cause stomach upset, nausea, or acid reflux, especially when consumed in large quantities or on an empty stomach.
Contamination Risk: Low-quality matcha, particularly from unregulated sources, may contain heavy metals like lead and other contaminants, as the whole tea leaf is ingested.
Iron Absorption Inhibition: The tannins in matcha can hinder the absorption of non-heme iron, an issue for those with low iron levels or anemia.
Moderate Consumption Advised: Most negative effects are linked to overconsumption. Limiting intake to 1–2 cups per day and choosing high-quality, organic matcha can prevent most problems.

Matcha, the vibrant green tea powder made from finely ground leaves, has gained immense popularity for its unique flavor and impressive health benefits. Unlike regular green tea, where leaves are steeped and removed, matcha involves consuming the entire leaf, resulting in a more concentrated dose of nutrients—and potential risks. While generally safe in moderation, excessive consumption or low-quality products can lead to several negative side effects.

Caffeine Sensitivity and Overload

One of the most common issues with matcha stems from its concentrated caffeine content. A single cup of matcha can contain significantly more caffeine than a cup of regular green tea, though often less than a cup of coffee. The exact amount depends on the matcha grade and how it's prepared, but for those sensitive to stimulants, even a small amount can trigger side effects.

Jitters and anxiety: Excessive caffeine can overstimulate the nervous system, leading to feelings of restlessness, shakiness, or anxiety.
Insomnia: Drinking matcha late in the day can interfere with sleep patterns and cause insomnia, a common problem with most caffeinated beverages.
Heart palpitations: Too much caffeine can result in an abnormal or racing heartbeat, especially in sensitive individuals.

Matcha's caffeine is often accompanied by L-theanine, an amino acid that promotes relaxation and helps moderate the jittery effects. However, this balance doesn't eliminate the risk of caffeine-related issues for everyone, especially if too much is consumed.

Digestive Problems

Matcha contains tannins and catechins, compounds that, while providing antioxidant benefits, can irritate the stomach lining, especially when consumed on an empty stomach or in large amounts.

Upset stomach: Nausea, stomach aches, and general digestive distress can occur due to the tannins.
Diarrhea or constipation: The high fiber and caffeine content can have a mild laxative effect for some, while for others, tannins may slow digestion, leading to constipation.
Acid reflux: Increased stomach acidity from high tannin content can exacerbate symptoms of acid reflux.

Contamination with Heavy Metals and Pesticides

One of the most concerning risks associated with matcha, particularly cheaper or low-quality varieties, is contamination with heavy metals like lead, cadmium, and arsenic. Since you consume the entire tea leaf when drinking matcha, any contaminants present in the soil where the plant is grown are ingested directly.

Higher risk with cheap matcha: Cheaper matcha, often from less-regulated regions, is more likely to be grown in contaminated soil or with pesticides.
Japanese vs. Chinese matcha: Studies and reports have consistently shown that Japanese-grown matcha contains significantly lower levels of lead than matcha from China, a result of stricter regulations and soil quality. Reputable brands provide third-party lab testing results to prove their products are free of heavy metals and pesticides.

Interference with Mineral Absorption

The tannins in matcha can also interfere with the body's absorption of iron, particularly non-heme iron found in plant-based foods. For those with iron deficiency or anemia, this can be a significant concern. To mitigate this, it's advisable to avoid drinking matcha during or immediately after meals, especially if eating iron-rich foods. Adding milk to matcha can also inhibit iron absorption further.

Impact on the Liver

While some research suggests green tea can benefit liver health, high doses, particularly from extracts or supplements, have been linked to potential liver toxicity. This is more of a concern with concentrated green tea extracts rather than regular matcha tea, but excessive consumption should still be approached with caution. Those with pre-existing liver conditions should consult a doctor before making matcha a regular habit.

A Comparison of Matcha vs. Coffee


Feature	Matcha	Coffee
Caffeine Content	Approximately 35–70mg per cup (1–2 tsp powder), but variable.	Approximately 95–200mg per cup, depending on brew method.
Energy Boost	Slower, sustained energy due to L-theanine, avoiding jitters and crashes.	Rapid spike in energy followed by a potential crash.
Anxiety Potential	Lower risk of anxiety due to the calming effects of L-theanine, but not absent.	Higher potential for causing anxiety and jitters.
Digestive Impact	Tannins can cause stomach irritation, especially on an empty stomach.	Higher acidity can trigger digestive issues in sensitive individuals.
Antioxidant Levels	Very high due to consuming the whole leaf.	Contains antioxidants, but generally lower levels than matcha.
Cost	Often more expensive due to complex cultivation and processing.	Typically less expensive per serving.

Conclusion: How to Enjoy Matcha Safely

While matcha offers a wealth of antioxidants and a gentle, sustained energy boost, it is not without potential downsides. Most of these negative effects, from caffeine jitters to digestive upset and heavy metal exposure, are linked to overconsumption or choosing low-quality products. The key to mitigating these risks is moderation and quality control. Limit your intake to 1–2 cups per day, purchase ceremonial-grade matcha from reputable Japanese sources that provide third-party testing, and avoid consuming it on an empty stomach. By doing so, you can enjoy matcha's many health benefits without the unwanted side effects. If you have pre-existing health conditions or are pregnant, consulting a healthcare provider is always recommended.

For more information on the impact of catechins on health, a deeper look can be found in a study published in the Critical Reviews in Food Science and Nutrition.

How to Choose Safe Matcha

Choose Japanese Origin: Japanese matcha is held to stricter safety standards regarding pesticides and heavy metals compared to matcha from other regions like China.
Opt for Organic: Certified organic products minimize the risk of pesticide residues.
Request Lab Testing: Reputable brands often provide third-party lab testing results for heavy metals and other contaminants upon request.
Distinguish Grades: Ceremonial-grade matcha typically uses younger leaves, which absorb fewer heavy metals, making it a safer and higher-quality choice than culinary-grade options.
Buy from Trusted Sources: Avoid untraceable or heavily discounted matcha, as it is more likely to contain harmful contaminants or fillers.

Frequently Asked Questions

Yes, matcha contains caffeine, and excessive consumption can cause anxiety, jitters, or a rapid heartbeat, especially in people sensitive to stimulants. However, the L-theanine in matcha helps to promote a state of calm alertness, often mitigating these effects compared to coffee.

While excessive doses of green tea extracts have been linked to potential liver issues, drinking moderate amounts of pure matcha tea is generally not a concern. In fact, some studies suggest matcha can even support liver health. The risk is highest with high-dose supplements, not with regular tea.

Yes, some people experience digestive issues like nausea, stomach cramps, or acid reflux due to the tannins in matcha, especially when drinking it on an empty stomach or in large amounts. Drinking matcha with food can help minimize this effect.

There is a risk of heavy metal contamination, including lead, especially in low-quality or non-organic matcha grown in contaminated soil. To minimize this risk, purchase ceremonial-grade matcha from reputable Japanese sources that provide third-party testing results.

Yes, the tannins in matcha can interfere with the body's ability to absorb iron, particularly non-heme iron from plant sources. Individuals with iron deficiency or anemia should avoid consuming matcha with meals to limit this effect.

For most healthy adults, excessive consumption starts when you exceed about 400 mg of caffeine per day, which is roughly 6 to 12 cups of matcha, depending on preparation. Side effects can occur at lower levels for those sensitive to caffeine. Moderation, typically 1–2 cups daily, is recommended.

While rare, an allergy to matcha is possible, as with any food. Symptoms may include hives, swelling, or breathing difficulties, and an allergy is different from a caffeine sensitivity. Those with known allergies to other teas or pollen may be more susceptible.