Matcha Side Effects: What You Need to Know

Matcha is famous for its wellness benefits and gentle energy, but it can also cause side effects if consumed the wrong way. In this in-depth guide, we cover the precautions to take, what’s happening in the body, and how to enjoy matcha comfortably—without unwanted reactions.

Matcha tea is celebrated for its health benefits—but what about side effects? Discover the precautions to take and how to drink matcha so you get the best of it, without discomfort.

Reading time: 10 minutes

Why can matcha cause side effects?

Matcha is powdered green tea leaves that you consume whole, which means a higher concentration of caffeine, catechins (EGCG), and L-theanine. That nutrient density explains matcha’s antioxidant and energising benefits, but it can also feel “too much” if your tolerance is lower or the dose is not adapted. Everyone reacts differently to tannins, caffeine, and fibre—so side effects can appear depending on the amount and when/how you drink it.

Most side effects are mild and temporary, and understanding the mechanisms helps you adjust your routine to enjoy matcha at its best.

Matcha’s nutritional profile

Matcha contains roughly 30 mg of caffeine, 20–25 mg of L-theanine, and 100–125 mg of catechins per gram. It also provides vitamins A, C and E, plus magnesium, calcium, and fibre. This richness supports its benefits—but also means you should dose sensibly to avoid excess caffeine or tannins.

Key nutrients at a glance

Common side effects

1. Sleep disruption

Caffeine’s half-life is around 5–6 hours, meaning a matcha can still be active at bedtime if you drink it late. To reduce the risk of insomnia, aim to drink matcha before 2 pm and stick to a morning cup or early afternoon.

2. Nervousness & palpitations

At higher doses, caffeine can trigger palpitations and restlessness, even though L-theanine partly balances this effect. If you’re prone to anxiety, lower the dose to 0.5–1 g and space out your intake.

3. Digestive discomfort

Because you’re ingesting the whole leaf powder, you also consume tannins and fibre. These can cause nausea, cramps, or heartburn—especially on an empty stomach. To minimise discomfort, start with half a teaspoon and increase gradually.

Less common side effects

Iron absorption sensitivity

Matcha’s polyphenols may reduce the absorption of non-heme iron. If you’re at risk of iron deficiency, space matcha away from iron-rich meals or speak with a healthcare professional.

“Detox-like” reactions

Matcha can stimulate digestion, which may temporarily increase bowel movements or cause mild diarrhoea. This is usually short-lived and tends to fade after a few days.

Medication interactions

Matcha may amplify or reduce the effects of certain medications (such as anticoagulants or beta-blockers). If you’re on medication, consult your doctor.

At-risk groups & recommendations

Pregnant people, those with heart conditions, anxiety, or ulcers should be cautious. Children and teens—more sensitive to caffeine—should limit or avoid matcha.

Recommended matcha habits

Dosage & timing

For most people, 1–2 g per day is plenty. Start with 0.5 g and increase based on tolerance. Drink matcha in the morning or before 2 pm to avoid sleep disruption.

Drink it with food

Enjoy matcha with a light meal (fruit, yoghurt, cereal) to soften the impact of tannins and reduce gastric irritation.

Choosing the right product

Choose an organic ceremonial matcha with a vibrant green colour and no additives. Higher quality also helps reduce risks linked to contaminants.

Studies & optimal dose

Some research suggests that moderate intake (around 2 g/day) can support alertness and reduce oxidative stress without exceeding common safety thresholds. Other studies on green tea compounds indicate potential benefits when taken before exercise, including endurance support and improved fat oxidation—while maintaining a clear, focused mind.

Extra practical tips

• Hydration: Aim for 1.5–2 L of water per day to balance matcha’s mild diuretic effect.
• Rotate: Alternate matcha with rooibos and caffeine-free herbal teas to reduce habituation.
• Storage: Keep matcha cool and away from light, in an airtight container.

Conclusion

Matcha is a powerful drink—offering clean energy, antioxidants, and mental clarity. Side effects are usually mild when you follow simple guidelines: choose high-quality organic matcha, adapt the dose to your tolerance, and avoid drinking it too late in the day.