6 Serious Side Effects of Drinking Too Much Green Tea

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Green tea has earned its reputation as one of the world’s healthiest beverages — packed with antioxidants, metabolism-boosting compounds, and powerful polyphenols. But like anything, too much of a good thing can quickly turn into a problem.

While moderate consumption (1–3 cups per day) is generally safe and beneficial, drinking green tea excessively may lead to surprising and sometimes serious side effects.

If you regularly consume large amounts of green tea, or rely heavily on green tea extracts or supplements, here are six important risks you should be aware of.

1. Digestive Issues and Stomach Irritation

Green tea naturally contains tannins — compounds that increase stomach acidity. In small amounts, most people don’t notice anything. But when consumed excessively, tannins can irritate the stomach lining and lead to:

Nausea

Stomach cramps

Acid reflux

Bloating

Drinking green tea on an empty stomach often makes symptoms worse. People with gastritis or ulcers should be especially careful.

How to avoid this:

Drink green tea with food and limit yourself to a moderate amount. If stomach discomfort persists, switch to milder herbal teas like chamomile or ginger.

2. Iron Deficiency Due to Reduced Absorption

One lesser-known downside of drinking too much green tea is its ability to interfere with iron absorption. Polyphenols in green tea bind with iron in the digestive tract, preventing the body from using it efficiently. Over time, this can contribute to iron deficiency, especially in:

Women

Vegetarians

Individuals with low iron intake

People with anemia

If you drink multiple cups a day, make sure to consume iron-rich foods and avoid drinking green tea immediately before or after meals.

Tip:

Pair iron-rich foods with vitamin C to enhance absorption.

3. Insomnia and Sleep Disturbances

Many people don’t realize how much caffeine green tea contains. While it’s less than coffee, drinking several cups — or concentrated green tea extracts — can lead to:

Difficulty falling asleep

Light, restless sleep

Waking up frequently

Feeling jittery or anxious

Caffeine affects everyone differently, but children, pregnant women, and people sensitive to stimulants should be especially cautious.

Solutions:

Avoid green tea after 4 PM

Choose decaffeinated green tea

Replace evening cups with calming herbal teas

4. Liver Stress and Potential Liver Damage

This is one of the most serious risks — and it’s linked mainly to green tea extract supplements, not the drink itself. Concentrated supplements may overload the liver with excessive catechins, especially EGCG, which can cause oxidative stress in liver cells.

Symptoms of liver stress may include:

Abdominal pain

Jaundice (yellowing of skin or eyes)

Dark urine

Extreme fatigue

While drinking regular green tea is generally safe, taking high-dose green tea extracts has been associated with liver toxicity in some individuals.

Better choice:

Stick to brewed green tea instead of highly concentrated supplements unless prescribed by a doctor.

5. Rapid Heartbeat, Nervousness, and Increased Anxiety

Green tea’s caffeine content can increase heart rate and stimulate the nervous system. Drinking too much may result in:

Heart palpitations

Nervousness

Irritability

Anxiety spikes

Shaky hands

People with anxiety disorders or heart conditions should monitor their intake carefully. Even “healthy” beverages can overstimulate the body if consumed in excess.

Try:

Limiting intake to 2–3 cups per day and spacing them several hours apart.

6. Headaches and Dizziness

Some individuals experience headaches after drinking large quantities of green tea due to caffeine sensitivity or dehydration. Since caffeine is a natural diuretic, excessive intake can lead to fluid loss, resulting in dizziness or lightheadedness.

Additionally, green tea contains small amounts of L-theanine, which affects brain function. In moderation, it promotes focus and calmness — but in excess, it may overstimulate the brain when combined with caffeine.

Prevention:

Stay hydrated, reduce intake, and observe how your body reacts.

How Much Green Tea Is Safe?

For most adults, 1 to 3 cups per day is considered safe and beneficial. The problems usually occur when people drink 6–10 cups daily, or when they consume high-dose supplements that contain far more catechins than the tea itself.

If you enjoy green tea regularly, the key is balance. Pair your intake with water, avoid drinking it on an empty stomach, and watch for signs of caffeine overload.