Short answer

We found no documented interaction between Magnesium 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.

Magnesium

What it is: An essential mineral the body uses for muscle and nerve function, blood sugar and blood pressure control, and making protein, bone and DNA.

What the research says: Supplements may lower blood pressure slightly. People who get more magnesium from food tend to have a lower risk of type 2 diabetes, and it matters for bone health.

Cautions

• Adults shouldn't take more than 350 mg a day from supplements unless a clinician advises it.
• Too much from supplements can cause diarrhea, nausea and stomach cramps.

Medicines to check

• Osteoporosis medicines (bisphosphonates) and some antibiotics: take them apart from magnesium
• Diuretics
• Long-term acid-reflux or ulcer medicines can lower magnesium levels

In Holitro: Magnesium Glycinate (133 mg per capsule)

Source: NIH Office of Dietary Supplements: Magnesium: Fact Sheet for Consumers (updated March 2021)

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.