Is It Safe To Take L-Theanine With Antidepressants?

The pharmacist discusses whether or not it is safe to take L-Theanine if you are taking antidepressant medication.


I am currently taking Zoloft. I have heard about taking L-Theanine and want to make sure it does not interact with antidepressants.

Asked by Buddy On Aug 01, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Aug 01, 2022
Last updated Sep 27, 2023

Key points

  • Although L-theanine may affect certain neurotransmitters, such as GABA, and serotonin, no interactions have been reported between it and any antidepressant medication.

There is no known drug interaction between L-Theanine and any antidepressant medications. In fact, no literature exists that has reported any interaction between L-Theanine and:

  • SSRI antidepressants (e.g. Zoloft, Lexapro, Paxil, Celexa)
  • Wellbutrin
  • SNRI antidepressants (e.g. Effexor, Cymbalta)

Below, we discuss why individuals may consider taking L-Theanine and how it may help depressive and other cognitive symptoms.

How L-Theanine Works

L-Theanine is a major, non-essential amino acid meaning our bodies produce it in sufficient amounts and therefore, isn't required from our diet. Nevertheless, it is found in abundance in green tea and other foods, including mushrooms. 

Historically, L-Theanine has been used for:

  • Reducing anxiety and stress
  • Depression
  • Preventing Alzheimer's disease
  • Treating attention deficit-hyperactivity disorder (ADHD)
  • Improving cognitive performance

Certain studies have pointed to the beneficial effects of L-Theanine in regard to cognitive performance specifically. One such study, published in Neuropharmacology,  showed that taking L-Theanine 100 mg prior to cognitive testing reduced the rate of errors compared with placebo in adults.

L-Theanine Mechanism Of Action

L-Theanine, as a major amino acid, has numerous effects on the body. In terms of its cognitive effects, L-Theanine might work for anxiety and depressive symptoms by increasing levels of GABA (an inhibitory neurotransmitter) and serotonin according to studies.  It is also thought to work by reducing the release of glutamate (an excitatory neurotransmitter).

It is important to note that some studies have reported that L-Theanine might decrease serotonin in the brain by enhancing the degradation of the neurotransmitter as well as inhibiting the enzyme responsible for serotonin synthesis. These results have only been seen in mice, however.

L-Theanine Interaction With Antidepressants

Although it appears that L-Theanine does influence serotonin levels, there are no documented interactions with antidepressants. Nevertheless, most antidepressants do affect serotonin levels by inhibiting re-uptake in the brain. It is uncertain whether or not L-Theanine will change this action. As L-Theanine is naturally produced in our bodies, and there are few, if any reports of adverse effects with L-Theanine, interactions seem unlikely.

L-Theanine Dosing

Studies for L-Theanine have used varying doses for different indications. These doses include the following:

Cognitive performance: Doses of 100 mg prior to cognitive testing has been used safely. In addition, combination doses of 30-100 mg of caffeine and 12-100 mg of L-Theanine have been used with no adverse effects.

Stress And Anxiety: Single doses of 200 mg prior to a stress-inducing exam have been used safely. The daily dosing of L-Theanine 200 mg twice daily has also been reported with no adverse effects.

ADHD: 200 mg of L-Theanine twice daily for 6 weeks has been used in boys with no adverse effects.

Final Words

Thanks for your question and feel free to reach out again in the future!


  • Theanine-induced reduction of brain serotonin concentration in rats, PubMed
  • The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans, Pubmed
  • Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task, PubMed

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at! You can also connect with Dr. Brian Staiger on LinkedIn.

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