Theanine Interactions Overview

Check For Interactions With Theanine


Theanine Theanine, often referred to as L-theanine as that is the predominant isomer of theanine, is an amino acid commonly found in tea leaves, particularly in green tea. It is purported to increase levels of GABA, serotonin, and dopamine in the brain, which can help to reduce stress and anxiety. L-theanine may also promote a sense of calm and improve overall well-being. Some studies have also suggested that it may improve cognitive function, although more research is needed. Most reported drug interactions with theanine are due to its sedative effects.
There are 557 drugs known to interact with Theanine

Additional Details

Is L-Theanine Safe? Are There Any Warnings?

L-Theanine is generally considered safe when taken orally and in appropriate doses for short periods. Clinical studies have used doses of up to 900 mg daily for 8 weeks without significant side effects. However, there isn't enough information to determine its long-term safety, especially during pregnancy and lactation. Children have used specific L-theanine products safely for short periods, but caution is advised.

How Does L-Theanine Work? What Is the Mechanism of Action?

L-Theanine works through various mechanisms to potentially provide its benefits:

  • Anxiety and Relaxation: L-Theanine may increase levels of relaxing neurotransmitters like GABA and serotonin.
  • Cognition and Mood: It affects glutamate pathways, possibly impacting synaptic plasticity, cognitive function, and mood regulation.
  • Antioxidant Effects: L-Theanine's breakdown products contribute to antioxidant processes, protecting against oxidative damage.
  • Attention and Focus: When combined with caffeine, L-Theanine may enhance alpha-wave activity, improving attention.
  • Immunomodulation: L-Theanine might boost immune responses and influence cytokine production during infections.


L-Theanine is absorbed through the intestines and reaches peak concentration in the blood about 50 minutes after ingestion. It's distributed to both blood plasma and red blood cells, and it can cross the blood-brain barrier. The amino acid is broken down in the intestines and has an elimination half-life of about 0.8 to 1.2 hours. The majority of ingested L-theanine is excreted in the urine.

Interaction Overview

L-Theanine may interact with certain medications and supplements:

  • Caution with antihypertensive drugs due to potential blood pressure-lowering effects.
  • Minor interaction with CNS depressants, possibly enhancing sedative effects.
  • Potential interaction with herbs and supplements that have hypotensive effects.

Common Side Effects To Watch For

Common side effects of L-Theanine can include drowsiness and headaches, especially when taken orally.

Are Supplements Standardized?

L-Theanine supplements can vary in their formulations. The predominant form of L-theanine found in tea is used in most clinical research. Some products may contain a mixture of L-theanine and D-theanine.

What Is L-Theanine Typically Used For?

L-Theanine has been studied for various potential uses:

  • Anxiety and Stress: It may help reduce anxiety and stress levels, possibly by affecting neurotransmitters like GABA.
  • Cognitive Function: L-Theanine might improve cognitive function and attention, especially when combined with caffeine.
  • Depression: Some research suggests it could have positive effects on mood and depression symptoms.
  • Immune Support: L-Theanine may modulate immune responses and help during infections.
  • Weight Loss: Animal studies suggest it might contribute to weight loss in combination with other compounds.

Dosing & Administration

L-Theanine is typically taken orally in doses of 200-400 mg daily for 4-8 weeks. Specific dosing recommendations vary based on the intended use.

Drugs that interact with Theanine

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Disclaimer: This drug-herbal interaction checker is provided for informational purposes only and should not be used as a substitute for the advice of a healthcare professional. The information contained in this tool is not intended to diagnose, treat, cure, or prevent any disease.

Additionally, this tool does not reflect all of the possible interactions. The way that herbs and medications interact with each other can be complex and is not always fully understood.