Can I Take L-Theanine and Magnesium Together?

Taking supplements can feel like a chore since you must remember to take them at the right time every day. And it is even more tedious when you have to swallow two or more at once.

L-Theanine and magnesium are well-known supplements, but using them together became especially popular after Taylor Swift mentioned it is her go-to combination for fighting stress and anxiety.

So, are you ready to learn more about these supplements and their potential synergistic effects?

I’ll explain everything in simple terms, so you don’t have to be a scientist to understand it. By the end, you’ll have a complete answer to your question, “can I take l-theanine and magnesium together?”

Is it Safe to Take L-Theanine and Magnesium Together?

The body does not produce L-theanine; it is found primarily in green tea leaves. Theanine increases the production of many neurotransmitters, including serotonin and dopamine, making it a popular natural sleep aid and stress reliever. (1)

Magnesium is a mineral that is indispensable for many functions, like ATP metabolism, DNA/RNA synthesis, and activation of vitamin D. (2)

I’m telling you all this to explain why it is safe for healthy adults to take them together. They are necessary (Mg in particular) for our bodies and, therefore, will not jeopardize our health or well-being. Also, both supplements are widely available over-the-counter, which tells you even more about their harmlessness.

In sporadic cases, some people may be allergic to L-Theanine or magnesium. If you experience any usual allergy symptoms, stop taking the supplement and seek medical attention immediately.

Will Taking L-Theanine and Magnesium Together Lead to Additional Benefits?

Some studies suggest that these two supplements might synergistically provide additional benefits. (3) (4)

They can supposedly work together with two things – the blood-brain barrier and bioavailability. Magnesium can assist L-Theanine to cross the blood-brain barrier, while they can help each other to be more bioavailable.

However, it is important to note that the research on the potential synergistic effects of L-Theanine and magnesium is limited. Most studies have examined the benefits of each supplement separately or weren’t conducted on humans.

What we know for sure is that magnesium and theanine promote relaxation and reduce stress. That is why it is recommended to take them anyway because they will undoubtedly improve such an effect on your brain and nervous system

What is the Best Dosage of L-Theanine and Magnesium to See Results?

The recommended dietary allowance for magnesium is about 300 mg for women and 400 mg for men. This includes the magnesium you get from the food and any supplements. You don’t want a magnesium deficiency, but hypermagnesemia is also dangerous. (5) (6) So, taking around 200 mg of magnesium as a supplement is desirable.

There is no RDA for theanine, and 200 to 400 mg daily is recommended, although the safe dose is significantly higher, up to 1000 mg.

Whether you take one supplement that contains both or take them separately, check the amount and stick to the recommended dosage.

What Time of Day Should L-Theanine and Magnesium Be Taken?

The optimal timing for taking theanine is in the evening, before bed, to relax you and improve sleep quality. Magnesium can help with the same, but also boost energy levels. Therefore, you can use it earlier in the day as well.

These are just general guidelines, and the timing may vary depending on your individual needs and lifestyle. Splitting the doses and taking L-Theanine in the morning and evening while taking magnesium in the afternoon may be the best possible schedule for many people.

Also, feel free to experiment. Each person is unique, and you may find that a completely different timing is the most effective for you.

How Long Will it Take to See Results from Magnesium and L-Theanine?

For magnesium, the time it takes to see results can depend on the specific health condition being treated and the type of magnesium you are taking. Tablets will take a few weeks, while topical magnesium can work instantly because the skin absorbs it instead of going through the digestive system. On the other hand, it is questionable how potent topical magnesium is.

L-theanine is fast-acting, so you can expect benefits in less than an hour. Still, it is more effective when taken consistently over a longer period.

Both shouldn’t be considered quick fixes for health issues, even if you experience a synergistic effect.

Do You Need to Cycle on and Off Magnesium and L-Theanine?

No clear evidence suggests that cycling on and off L-Theanine and magnesium is necessary.

I think that you can take magnesium continuously because it is practically impossible to overdose on magnesium.

You can cycle theanine if you believe you will build a tolerance over time. In my experience, it is not addictive, nor it loses efficiency. If you still decide to cycle theanine, you can try products with similar benefits and similar/different mechanisms of action, such as glutamate and ashwagandha.

Are There Any Side Effects of Magnesium and L-Theanine?

L-theanine and magnesium are most likely safe when taken by month at the recommended dosages for 8 to 12 weeks. They are considered safe both together and individually.

Like any substance, they may trigger mild side effects, such as headache, nausea, diarrhea, sleepiness, or dizziness. In addition to the fact that side effects are mild, they are also very rare and short-lived.

Before incorporating a new supplement into your regimen, you should also speak with your doctor since both Mg and theanine could potentially interact with heart medicines.


You won’t get a magical potion by combining L-Theanine and Magnesium, but with consistency, you might notice some positive changes in your overall mood, cognitive abilities, and well-being.

Remember, I’m not here to convince you to take these supplements – instead, I give you the facts and let you decide what’s best for you.

Until next time, take care of yourselves and keep exploring the wonderful world of supplements!

What to Read Next

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Can Low Magnesium Kill You
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