Side effects of green tea

6 Possible Side Effects of green tea

Green tea hailed for its numerous health benefits, has gained popularity as a beverage and dietary supplement. Packed with antioxidants and bioactive compounds, green tea offers a range of advantages, from boosting metabolism to supporting heart health. However, like any substance, green tea is not without its potential side effects. While most people can enjoy green tea without adverse reactions, it is important to be aware of the potential risks and limitations. In this article, we will delve into the possible side effects of green tea, exploring factors such as caffeine sensitivity, interactions with medications, and risks associated with excessive consumption.

By understanding the potential drawbacks of green tea, individuals can make informed decisions about their consumption and ensure they reap its benefits while minimizing any potential harm.

Side effects of green tea

  1. Caffeine Sensitivity: Green tea contains caffeine, albeit in lower amounts compared to coffee. While moderate caffeine intake is generally safe for most people, individuals who are sensitive to caffeine may experience adverse effects. Green tea disadvantages include restlessness, nervousness, increased heart rate, irritability, and difficulty sleeping. Those with caffeine sensitivity should be cautious with green tea consumption, especially in large quantities or close to bedtime.
  2. Stomach Discomfort and Digestive Issues: Green tea contains tannins, a type of polyphenol that can have an astringent effect on the stomach lining. Some individuals may experience stomach discomfort, including nausea, stomach ache, or acid reflux, after consuming green tea. Additionally, excessive consumption of green tea on an empty stomach may lead to digestive issues, such as diarrhea or constipation. It is advisable to consume green tea in moderation and with food to minimize the risk of stomach-related discomfort.
  3. Interactions with Medications: Green tea contains compounds that can interact with certain medications, potentially affecting their efficacy or increasing the risk of side effects. For example:
  • Blood Thinners: Green tea contains vitamin K, which can interfere with blood thinning medications like warfarin. It is essential for individuals on blood thinners to consult with their healthcare provider before increasing their green tea consumption.
  • Medications for High Blood Pressure: Green tea, particularly when consumed in large amounts, may slightly increase blood pressure due to its caffeine content. If you are taking medications for high blood pressure, it is advisable to discuss green tea consumption with your healthcare provider.
  • Stimulant Medications: The caffeine content in green tea may interact with stimulant medications, such as those prescribed for attention deficit hyperactivity disorder (ADHD). It can potentially exacerbate the stimulant effects or increase the risk of side effects.
  1. Iron Absorption Interference: Green tea contains catechins, which have been shown to inhibit the absorption of non-heme iron from plant-based sources. While this may not be of concern for individuals with sufficient iron levels, it can pose a risk for those with iron deficiency or anemia. If you are relying on plant-based sources of iron or have low iron levels, it is advisable to consume green tea between meals rather than with meals to minimize the impact on iron absorption.
  2. Pregnancy and Lactation: Although moderate green tea consumption is generally considered safe during pregnancy and lactation, it is important to exercise caution. The caffeine content of green tea should be taken into account, and it is advisable to limit overall caffeine intake during these periods. High caffeine intake has been associated with an increased risk of adverse pregnancy outcomes, including low birth weight and preterm birth. It is recommended to consult with a healthcare provider for specific guidance on green tea consumption during pregnancy and lactation.
  3. Excessive Consumption and Oxalate Content: While green tea offers various health benefits, consuming excessively large amounts can have adverse effects. Excessive green tea consumption, especially in the form of supplements or concentrated extracts, can lead to high levels of catechins in the body. This can potentially contribute to liver toxicity and may increase the risk of liver damage. Furthermore, green tea contains oxalates, which can contribute to the formation of kidney stones in susceptible individuals. It is important to consume green tea in moderation and be mindful of the total intake from all sources.


Green tea is generally safe and offers numerous health benefits. However, it is essential to be aware of the potential side effects of green tea consumption. Caffeine sensitivity, interactions with medications, stomach discomfort, iron absorption interference, considerations during pregnancy and lactation, and risks associated with excessive consumption should be taken into account. By understanding these potential side effects and exercising moderation, individuals can enjoy the benefits of green tea while minimizing any potential risks to their health and well-being.

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