Doses of up to 900 mg daily have been safely used for 8 weeks. It isn't clear if L-theanine is safe to use for longer periods of time. It might cause mild side effects, such as headache or...

Feb 20, 2025 · L-theanine is an amino acid found in tea (Camellia sinensis) that's been studied for its effects on ADHD, anxiety, cognition, sleep, and more. Read on for more information about …

Oct 19, 2025 · Drinking high amounts of caffeinated teas that contain L-theanine may cause side effects like headache, dizziness, and rapid heartbeat. Most people can safely consume about …

Aug 13, 2025 · Comprehensive guide to L-Theanine by experienced pharmacists. Learn about benefits, dosage, side effects, and interactions backed by scientific research.

Jun 9, 2025 · Learn about the uses and potential benefits of L-Theanine including dosage guidelines, side effects, interactions and safety/efficacy ratings.

Possible side effects of l-theanine include headache, nausea, diarrhea, dizziness, irritability, or tremors. These are more likely when taken at higher-than-recommended doses.

Theanine may cause mild adverse effects, such as headache. Pregnancy and breast-feeding:There is not enough reliable information about the safety of using theanine if you are …

Dec 12, 2025 · Several clinical trials demonstrate L-theanine’s positive impact on key neurotransmitters (brain chemical messengers) involved with stress, sleep, mood, focus, and …

Nov 28, 2025 · Let’s explore seven possible side effects to help you make an informed decision: 1. Gastrointestinal issues. Stomach upset is a common side effect of L-theanine, often …

Sep 12, 2025 · Most healthy adults can take 200-500 mg per day. However, like any dietary supplement, it can cause side effects, especially when taken in high doses.