L-Theanine Side Effects: Is Theanine safe for long-term use?

Theanine is currently one of the most widely-used natural nootropics in the world. What few people realise is that most of us consume at least a little L-Theanine on a daily basis. It is an amino acid abundant in green and black tea, as well as kola nut, some mushrooms, and guarana. So every time you drink a cup of green or black tea, or eat certain mushrooms, you’re consuming a little bit of theanine.

A lot of people are also unknowingly aware of the benefits of L-Theanine. Part of the reason that tea is much less intense than coffee – despite containing  sizeable amount of caffeine – is the fact that tea is abundant in L-Theanine while coffee is not. The subtle, calm yet clear lift in focus and energy we get from tea is in large part the result of theanine affecting your brain chemistry in unique and exciting ways.

As theanine is increasingly used in the best nootropic supplements, we are receiving a growing number of questions from our readers regarding the safety of L-Theanine. In particular, people are concerned about the potential long-term side effects of L-Theanine, given that most nootropics using theanine recommend consistent, daily use.

In this article, we will look at L-Theanine side effects, long-term health risks, drug interactions, safe dosages, and the synergistic relationship between theanine and caffeine. Please post any questions in the comments section at the end.

How Does L-Theanine Affect The Brain?

To proprly discuss the side effects of L-Theanine supplementation, we need to first get to grips with what theanine does and how it interacts with the brain.

In other words, how does theanine affect the brain to produce the benefits it is associated with?

L-Theanine elevates levels of GABA, and to a lesser extent serotonin and dopamine. These neurotransmitters elevate mood, reduce anxiety, sharpen focus, increase motivation, and enhance cognitive performance more broadly.

Theanine also appears to have a synergistic relationship with caffeine. Reams of anecdotal data and dozens of clinical trials have shown that the administration of theanine alongside caffeine makes the stimulant both much more effective and far less likely to cause side effects.

In fact, theanine and caffeine produce greater improvements in focus, learning and memory than we see from either substance in isolation; not only does theanine make caffeine safer, it also makes it vastly more powerful.

How theanine does this exactly is open to debate. Studies have found that theanine actively counters many of the side effects of caffeine: reducing CNS activity, lowering blood pressure, easing muscle tension, and more. However, all of these effects can ultimately be traced back to theanine’s effect on the neurotransmitters in the brain.

Common Side Effects of L-Theanine

What are the most common side effects of L-Theanine supplements?

Theanine supplements are generally safe. Few people experience any side effects at all when using L-Theanine supplements. It doesn’t matter whether you are using L-Theanine or Suntheanine, or any other branded form of the amino acid for that matter; theanine is generally very well tolerated.

In fact, supplement stacks containing theanine in some form are significantly less prone to causing adverse effects than those without theanine; this is especially true of nootropic stacks or energy supplements containing caffeine.

However, some people do sometimes experience side effects from L-Theanine supplements. The most common side effects of L-Theanine include:

• Headaches
• Nausea
• Irritability
• Anxiety
• Drowsiness
• Dizziness
• Elevated heart rate
• Sleep disturbances

These L-Theanine side effects are rare, and when they do occur, they tend to be mild and transient. People who experience these side effects from L-Theanine invariably find that they stop once they stop using theanine.

Of course, you are signifciantly more likely to experience side effects from L-Theanine if you are taking it alongside other substances. A very common cause of theanine side effects is the mixing of theanine and alcohol. Alcohol does not usualy interact badly with theanine – in fact it can help with hangovers – but in some people the two substances react badly with one another, producing side effects such as drowsiness, brain fog and fatigue.

Taking high doses of L-Theanine also make side effects more likely, as does mixing it with multiple stimulants. When mixed with excessively large doses of caffeine theanine can actually make anxiety worse. High quality nootropics and caffeine pills will dose theanine properly and avoid negative interactions, which is why it is so important ot only use high quality, professionally made supplements!

We are not doctors and this is not medical advice. You must do your own research carefully before using any L-Theanine supplements. L-Theanine is unlikely to cause side effects, but theanine side effects can and do happen in some people. Talk to a doctor about your plans to use L-Theanine nd if you do experience side effects from theanine, stop using it and seek medical advice right away.

Is L-Theanine Safe For Long-Term Use?

Because theanine is such a common ingredient in daily nootropic stacks, it is worth considering the long-term effects of taking this amino acid. Is theanine safe to take daily for long periods of time?

Theanine is actually an ideal nootropic to take long-term. Not only is it safe for long-term, consistent use, but theanine actually becomes more rewarding when used frequently over prolonged periods of time.

Several clinical trials have specifically looked at the side effects of long-term theanine supplementation. In researching this question, we didn’t coem across a single study that raised conerns about the safety of long-term L-Theanine supplementation. No study looking at chronic theanine supplementation has found any meaningful adverse effects resulting from the use of even large daily doses of L-Theanine for periods of up to 8 weeks.

Studies looking at daily theanine use have actually found that more frequent use results in significantly better results. Specifically, daily theanine use for periods of 8 weeks or more seems to be associated with greater reductions in stress and anxiety and more noticeable improvements in focus and mental clarity than the ad hoc use of L-Theanine supplements.

Does L-Theanine Affect Blood Pressure?

However, we may not always want to lower blood pressure. High blood pressure is certainly a problem, but driving blood pressure too low can be just as problematic, leading to fainting, weakness, dizziness, and poor cognitive function.

So is theanine safe to take if you already have low blood pressure?

The answer is most likely yes. Unlike blood pressure medications like beta blockers or nitric oxide sprays, L-Theanine naturally promotes lower blood pressure by contering the things which cause high blood pressure. Put another way, theanine does not artificially suppress blood pressure. Rather, it seems to help prevent blood pressure from climbing in the first place while promoting healthy regulation of blood pressure over the long-term.

Conclusion: Is Theanine Safe?

L-Theanine is a fantastic natural nootropic and a great supplement to take alongside caffeine. Theanine is frequently used in both high quality brain supplements and powerful natural energy supplements due to its broad effects on focus, energy, anxiety, and mental clarity. It even makes for a fantastic sleep aid, with many sleep stacks using theanine as a central ingredient due to its ability to promote deep, restful sleep.

On top of all of this, L-Theanine supplements appear to be extremely safe.

Studies have shown that taking L-Theanine is safe and broadly side effect-free. Clinical trials looking at the use of theanine for enhancing focus, promoting sleep and reducing anxiety do not mention any notable or significant side effects at doses ranging from 100mg to 300mg per day. Importantly, studies looking at the long-term use of L-Theanine (i.e. 8 weeks of daily supplementation) have reported no serious side effects.

If you are looking to use L-Theanine to promote mental clarity, reduce anxiety, and attenuate the worst side effects of caffeine, then you probably don’t have to worry about side effects.

For the best results, we recommend using L-Theanine alongside other proven, potent, natural cognitive enhancers and anxiolytics. Our top rated nootropics tend to use theanine in combination with other, complimentary ingredients to produce dramatic improvements in focus, memory, learning, mental clarity, all while reducing anxiety.

Brian Johnson, PhD

Brian Johnson is current Editor of Vagarights.com and a long-time writer for VAGA. A former psychologist, Brian is passionate about improving mental health and finding ways to stave off cognitive decline. He is an expert on nootropics, cognitive enhancement and biohacking more broadly. You can see his work on Google scholar.