Peace, relaxation, better concentration and gentle energy - L-theanine seems to combine all the benefits of coffee, energy drinks and tea. The benefits of L-theanine are extensive. But are there any disadvantages or side effects of L-theanine supplements? What to do in the event of an overdose? We will try to answer these questions in our blog.

Is L-Theanine Safe and Legally Available?

Yes! In general, L-theanine is considered a safe dietary supplement. After all, it is the active ingredient also found in black and green teas. It has also been classified as a "safe dietary supplement" by the American Food Safety Authority (FDA). L-theanine with and without added caffeine is legal and is considered a safe nootropic. You can buy L-Theanin here

Does L-theanine have any side effects?

While it is extremely rare, L-theanine can cause side effects under certain circumstances. As with all nootropics, the following applies: If you are taking prescription medication or have previous illnesses, please discuss the use of L-theanine with a doctor in advance. And of course: always pay attention to the recommended dose of L-theanine! In addition, a distinction has to be made between tablets with pure L-theanine and in combination with caffeine. We have compiled the possible side effects:

Tablets with pure L-theanine

Slight gastrointestinal complaints
A rare side effect can be slight gastrointestinal discomfort (especially at the beginning of use). Therefore, at best, L-theanine should not be taken on an empty stomach, but about 15-30 minutes after a meal.

Low blood pressure
Just like green tea, L-theanine can have a calming, anxiety-relieving, stress-reducing effect and also might lower your blood pressure for a short time. Even if antihypertensive agents are already being taken, the dosage of L-theanine should be discussed with a medical professional and, if necessary, reduced to smaller doses than usual.

Headache and dizziness
Some users report mild dizziness and headaches, although a direct connection with L-theanine has not yet been proven. If you have a headache, we recommend the combination of L-theanine with caffeine, as this side effect has hardly been reported.

Combination of L-theanine with extra caffeine

Gastrointestinal problems and diarrhoea are common side effects of caffeine as they can have a laxative effect. It can occur in combination with L-theanine, especially if it is taken on an empty stomach.

Restlessness and headache
Common side effects of caffeine overdose. Also, sleep problems stand due to caffeine, but these undesirable effects are counteracted by the combination with L-theanine - one of the greatest advantages of this nootropic. Restlessness and headaches are extremely rare and may only be expected in high doses or because of interactions with other medications or agents (alcohol, caffeine tablets, etc.)

What should I do when I notice L-theanine side effects?

The side effects listed above are extremely rare. Nevertheless, every person reacts differently to substances and food supplements.

In addition to your physical constitution, this also depends on your lifestyle, diet, medication and previous illnesses.

The reaction to L-theanine also varies - while some users feel an effect with the first ingestion of a low dose (e.g. 50 mg), others need a lot more. Among other things, this also depends on how actively the metabolism and the absorption of amino acids are processed in the body. For this reason, L-theanine should not be taken on an empty stomach, as this can increase its effects.

The following applies when taking L-theanine:

- always start with a low dose
- wait for the reaction of the body
- choose the recommended dosage according to benefit and area of ​​application
- the higher the dose of L-theanine, the higher the likelihood of side effects
- avoid interactions - e.g. with medication, alcohol, etc.

Should slight L-theanine side effects occur:

- suspend the next dose and reduce the dose if necessary
- in future, take the dose approx. 30 minutes after eating

If the L-theanine side effects persist:

- stop taking
- consult with healthcare professionals

Is L-theanine overdose dangerous?

An L-theanine overdose can be compared to what happens when you drink more than 10 cups of green or black tea in a row. A cup of tea contains around 20 mg of natural L-theanine. As a dietary supplement, a dose of 200 mg is generally recommended (depending on the purpose, 1 to 2 times per day).

So what happens if the dose is over 400 mg per day? First of all, L-theanine (unlike caffeine) is not so addictive. Even with a single overdose of more than 400 mg, no danger is to be expected.

Some users, however, who intentionally take extremely high doses of L-theanine, report a kind of “high feeling”, which is described as being extremely relaxed or almost sedative.

For falling asleep in the evening, e.g. to combat the effects of caffeine or alcohol, 200 mg to 400 mg are recommended. These should only be taken before bed. Higher dosages are not necessary.

By the way, Raw Powders provide various nootropics, for better mood, sleep or overall health. All over-the-counter nootropics from Raw Powders can be found here.


Text author:
Kay Svegler
Communications, PR, American Studies, University of Leipzig
Journalist and freelance writer (e.g. Süddeutsche Zeitung, BILD, MDR etc.)
Former Senior PR Manager for Fischer Appelt, Sustainability and Diversity Manager for DKB