Can too much tea make you jittery? A deep dive into caffeine and L-theanine

November 18, 2025 •

3 min read

According to the Food and Drug Administration (FDA), up to 400 mg of caffeine daily is safe for most healthy adults, yet some individuals experience jitters from far less, raising the question: can too much tea make you jittery?. This article explores the biological reasons behind this phenomenon, focusing on caffeine and the unique calming compound, L-theanine.

Quick Summary

This guide explains why excessive tea consumption can cause jitteriness due to caffeine overstimulation, individual sensitivity influenced by genetics and lifestyle, and the counterbalancing effects of L-theanine. It covers different tea types, typical symptoms, and practical strategies to manage your intake effectively.

Key Points

Caffeine is the main cause: The jittery feeling from too much tea is primarily caused by excessive caffeine stimulating the central nervous system.
L-theanine moderates effects: Tea contains L-theanine, an amino acid that works to counteract the harsh, jittery effects of caffeine, promoting a state of calm alertness.
Individual factors matter: Your genetic makeup, age, metabolism, and health can significantly influence your sensitivity to caffeine and your likelihood of experiencing jitters.
Not all teas are equal: Different types of tea have varying caffeine levels, with black tea generally having more than green or white tea.
Hydration and snacks help: To combat jitters, stay hydrated with water and eat a healthy snack to slow caffeine absorption.
Herbal teas are caffeine-free: If you are very sensitive, consider switching to naturally caffeine-free herbal infusions like chamomile or peppermint.

The Core Culprit: Caffeine Overload

Just like coffee, tea contains caffeine, a natural stimulant that affects the central nervous system. When consumed in excess, caffeine can over-stimulate the body, leading to a cascade of physical and psychological effects commonly known as "the jitters". For most people, consuming more than 400mg of caffeine in a day is the threshold for negative side effects, but individual sensitivity varies dramatically.

How Caffeine Blocks Adenosine

At the molecular level, caffeine works by blocking adenosine receptors in the brain. Adenosine is a neurotransmitter that promotes relaxation and sleepiness; as it builds up throughout the day, it signals to your body that it's time to rest. Caffeine's interference with this process leads to increased alertness, but in large doses, this can become restlessness, a rapid heart rate, and an uneasy feeling.

The Role of L-theanine: A Calming Counterbalance

One key difference between tea and coffee is the presence of L-theanine, an amino acid unique to the Camellia sinensis plant. L-theanine promotes a state of calm alertness by increasing alpha brain waves and influencing neurotransmitters like serotonin and dopamine. This creates a smoother, more focused energy boost from tea compared to the sharper, more jarring effect of coffee. However, even with L-theanine, consuming a high volume of tea can overwhelm this calming effect, especially in sensitive individuals.

Factors Influencing Your Sensitivity to Tea's Caffeine

Several factors determine how your body reacts to the caffeine in tea, explaining why some people can tolerate more than others.

Genetics: Your genetic makeup, specifically the CYP1A2 and ADORA2A genes, significantly influences how quickly you metabolize caffeine. Slow metabolizers will feel the effects of caffeine more intensely and for a longer duration.
Age and Hormonal Changes: As we get older, our metabolism naturally slows down, meaning caffeine remains in the system for longer. Hormonal shifts during pregnancy or while on birth control can also affect how caffeine is processed.
Lifestyle and Health: High stress levels, lack of sleep, liver issues, and certain medications can all alter your caffeine sensitivity. For example, a high-stress day releases more adrenaline, and adding caffeine can compound this effect, triggering a more pronounced "fight or flight" response.

Comparison of Caffeine and L-theanine Effects


Feature	Caffeine (in excess)	L-theanine (in tea)
Primary Effect	Central nervous system stimulant	Promotes calm, alert relaxation
Jitteriness	Can cause or exacerbate restlessness, shakiness, and anxiety	Counterbalances the jittery effects of caffeine
Energy Type	Fast-acting, sometimes jarring and followed by a crash	Smoother, sustained energy boost
Sleep Impact	Inhibits melatonin production, leading to insomnia	Increases alpha brain waves, potentially aiding sleep
Cognitive Effect	Heightened alertness, but can lead to scattered focus	Improves attention and focus

Managing Tea-Induced Jitteriness

If you find yourself feeling jittery after too much tea, here are several steps you can take:

Reduce your intake: This is the most straightforward solution. Pay attention to how many cups you're consuming, especially later in the day, and scale back.
Switch to lower-caffeine teas: Different teas have varying caffeine levels. A cup of black tea contains more caffeine than green tea, while white tea has even less.
Stay hydrated: Drink plenty of water. Caffeine is a diuretic, and dehydration can worsen symptoms like shakiness and headaches.
Have a snack: Eating something can help slow the absorption of caffeine into your system.
Exercise lightly: A brisk walk can help burn off some of the excess nervous energy and distract your mind.
Practice mindful breathing: If you feel your heart racing or anxiety rising, deep, slow breathing can help regulate your heart rate and calm your nervous system.

Conclusion

Yes, for many individuals, consuming too much tea can absolutely lead to jitteriness. The amount of caffeine in tea, combined with individual metabolic rates, genetics, and lifestyle factors, determines your susceptibility to these stimulating effects. However, the presence of L-theanine provides a valuable balancing act that makes tea's buzz smoother than that of coffee. By being mindful of your intake, understanding your body's unique response, and knowing how to mitigate the symptoms, you can enjoy tea without the unwanted side effects. Ultimately, moderation is key to a balanced and healthy lifestyle.

Frequently Asked Questions

For most healthy adults, consuming more than 400 mg of caffeine per day (roughly 8-10 standard cups of black tea, but varies by type and brewing) may be considered too much. However, personal tolerance can cause adverse effects at much lower amounts.

Tea contains the amino acid L-theanine, which promotes relaxation and counteracts the intense jittery feelings associated with caffeine. Coffee does not contain L-theanine, resulting in a more direct, and sometimes harsher, stimulant effect.

Yes. Green tea generally contains less caffeine than black tea, and often has higher levels of L-theanine. This combination provides a calmer, more focused energy lift with a lower risk of causing jitters.

Yes. The longer you steep your tea and the hotter the water, the more caffeine will be extracted from the leaves. Using cooler water and shorter brewing times can help reduce the caffeine content.

The effects can last for several hours, depending on your individual metabolism. Caffeine has a half-life of about 4 to 6 hours, but symptoms may persist longer for slow metabolizers.

Excessive tea intake can also lead to sleep disturbances, headaches, digestive issues, and reduced iron absorption due to tannins. Overconsumption should be avoided, especially by sensitive individuals.

This could indicate high caffeine sensitivity or intolerance. Consider trying herbal teas, which are naturally caffeine-free, or consult a healthcare professional to rule out any underlying medical conditions.