Can I take Glutamine with Theanine?

Understanding the interactions, benefits, and safety of combining these two powerful supplements.

Glutamine
+
Theanine

Short answer

We found no documented interaction between Glutamine and L-theanine in the sources below. That isn't proof the combination is right for you: check each one's cautions, and ask your pharmacist if you take medication.

Glutamine

What it is: An amino acid the body makes and uses for energy and to build protein.

What the research says: It has little or no benefit for strength or recovery. It's studied mainly in cancer care and after surgery.

Cautions

  • Studies report no side effects at up to 45 g a day for several weeks; reported side effects elsewhere include headache and nausea.
  • Don't confuse it with glutamate, which is a different substance.

In Holitro: Glutamine (750 mg per capsule)

Sources: NIH Office of Dietary Supplements: Dietary Supplements for Exercise and Athletic Performance (updated March 2021); Memorial Sloan Kettering Cancer Center, About Herbs: Glutamine (updated September 2026)

L-theanine

What it is: An amino acid found in green tea, taken for calm and sleep.

What the research says: Small studies suggest it may improve sleep; results for anxiety are mixed.

Cautions

  • No side effects have been reported for the supplement.
  • It may not be safe in pregnancy or while breastfeeding.

Medicines to check

  • Sleep medicines and sedatives (such as lorazepam, diazepam or zolpidem): may add to drowsiness

In Holitro: Theanine 200mg (200 mg per capsule)

Source: Memorial Sloan Kettering Cancer Center, About Herbs: L-Theanine (updated July 2026)

Check with your doctor or pharmacist, especially if you take medication.

Check your stack — free

Educational information only, not medical advice. This reflects general ingredient overlap, not a personalized safety review. Always check with your doctor or pharmacist before combining supplements, especially if you take medication, are pregnant or nursing, or manage a health condition. These statements have not been evaluated by the FDA.

Stop Guessing Your Dosages.

Balancing dosages across multiple different bottles is risky, inefficient, and expensive. Glutamine is already lab-dosed in our Gut Pack, and Theanine is in our Sleep Pack — either way, that’s one less bottle to manage.

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