Side effects of green tea

Green tea, a beverage celebrated for its numerous health benefits, also carries potential side effects that are often overlooked. While it has been a staple in many cultures for centuries, heralded for its antioxidant properties and role in wellness rituals, this story has another side. This introduction delves into the less-discussed aspects of green tea consumption, aiming to provide a balanced perspective. Enthusiasts and casual drinkers alike must be aware of the potential negative impacts, ranging from sleep disturbances to interactions with certain medications.

Two cups of green tea in clear, glass tea cups ready to be served, there are some leave scattered in the foreground of the photo.

Despite its revered status in the world of teas, green tea is not without its drawbacks. Issues such as caffeine sensitivity, effects on iron absorption, and even risks during pregnancy and breastfeeding are important considerations.

Common Consumption Patterns

Green tea consumption patterns vary widely among individuals; some occasionally enjoy a cup, savouring it as a special treat. Meanwhile, others integrate it more deeply into their daily routines, often starting their day with a warm brew, with their regular intake ranging from one to several cups a day. Cultural influences actually play a significant role in these habits. For instance, in East Asian countries, it’s common to consume green tea throughout the day. In contrast, Western cultures might favour it as a morning or afternoon pick-me-up.

Diving deeper into these consumption habits, we notice variations in frequency and preparation methods. Traditional methods, such as those used in Japanese tea ceremonies, emphasize a more ceremonial approach to brewing green tea. These practices often involve specific types of green tea, like matcha, and can include a mindfulness aspect to drinking tea. Modern, fast-paced lifestyles, however, have led to the popularity of quicker brewing methods, such as using tea bags or instant tea powders. These methods might offer convenience but can differ significantly in the concentration of active ingredients compared to traditional brewing.

Potential Negative Side Effects

When trying to understand green tea’s potential negative side effects, it’s good to approach this topic with a balanced view. While the beverage is often praised for its health benefits, it’s crucial to acknowledge and understand the less favourable aspects that can impact certain individuals. This section aims to shed light on those issues, providing insights into how green tea might affect different people, depending on various factors like health conditions, consumption habits, and individual sensitivities.

Green tea contains caffeine, which can have various effects depending on the person. For some, it can cause nervousness, trouble sleeping, and even an increased heart rate; additionally, people with caffeine sensitivity might experience these effects more intensely. It’s also worth noting that consuming large amounts of green tea could lead to caffeine overload, which might aggravate these symptoms. Therefore, moderation is vital, especially for those who might be sensitive to caffeine’s negative effects.

Effects on Iron Absorption and Anemia Risk

Green tea contains a compound called tannins; the problem with tannins is that they can bind to iron from your foods, making it harder for the body to absorb iron. This effect is particularly relevant for individuals with iron deficiency, anaemia or anyone at risk of low iron levels. To mitigate this, it’s advisable to drink green tea between meals rather than with them, and we recommend pairing it with foods high in vitamin C to boost iron absorption.

Potential Liver Damage

Green tea is usually safe, but in rare cases, it might harm the liver. This risk is higher if you drink lots of green tea, especially on an empty stomach. Some signs of liver trouble include yellow skin, dark urine, or long-lasting tiredness. It’s wise to talk to a doctor if you drink a lot of green tea and have liver problems or other health issues. Remember, moderation is key to enjoying green tea safely.

Impact on Sleep and Anxiety

Green tea’s caffeine content can affect sleep and anxiety levels. For some, a cup of green tea offers a gentle energy boost, but for others, especially those sensitive to caffeine, it might lead to sleep problems like insomnia. Drinking it late in the day can disrupt sleep patterns, leading to less restful nights. In terms of anxiety, while green tea’s L-theanine can promote relaxation, the caffeine may counteract this, potentially increasing anxiety in sensitive individuals. It’s best to monitor how green tea affects your sleep and anxiety, adjusting your intake accordingly.

Risks During Pregnancy and Breastfeeding

During pregnancy and breastfeeding, it’s crucial to consider the impact of green tea consumption. Green tea contains caffeine, which crosses the placenta and can affect the fetus. High caffeine intake during pregnancy is linked to risks like low birth weight and even miscarriage. Moreover, caffeine can also be transmitted through breast milk, potentially affecting a nursing infant’s sleep and digestion. Hence, pregnant and breastfeeding mothers should limit their green tea intake.

Interactions with Medications

Green tea’s active compounds can sometimes interfere with certain medications, so this is an important aspect to consider if you are changing medication or considering adding green tea to your diet.

The main issues with this are primarily in how the body breaks down and uses drugs, especially blood thinners like warfarin. Green tea’s vitamin K content can reduce the effectiveness of these medications, potentially leading to complications in blood clotting.

Additionally, it can interact with some heart medications, altering their effectiveness. It’s wise to consult with a healthcare provider before including green tea in your routine for those taking any prescription drugs.


In wrapping up, it’s clear that green tea brings both benefits and potential risks. Its rich history and popularity worldwide speak to its value, yet it’s essential to consume it thoughtfully, considering individual health factors. Moderation is key, and staying informed about how it interacts with your body and any medications ensures you can enjoy green tea’s positives without facing the negatives.

About the author

Sophia Gouse, a passionate advocate for the art and culture of green tea, is the creative force behind this blog. Her writing offers a rich tapestry of content, from detailed reviews of green tea varieties, guides on brewing techniques, health benefits of teas and explorations of tea culture around the world.

Headshot of the author, Sophia Gouse