L-Theanine Dosing for ADHD
L-theanine is not a guideline-recommended treatment for ADHD and should not replace FDA-approved stimulant medications (methylphenidate or amphetamines) as first-line therapy, but if used as an adjunctive or alternative intervention, the evidence supports 400 mg daily (200 mg twice daily) as the most effective dose. 1, 2
Guideline-Recommended First-Line Treatment
Before considering L-theanine, understand that established ADHD guidelines do not include it as a recommended treatment:
Stimulant medications (methylphenidate or amphetamines) remain the evidence-based first-line pharmacological treatment for ADHD across all age groups, with 70-90% response rates when both agents are tried sequentially. 3, 4, 5
The American Academy of Child and Adolescent Psychiatry, American Academy of Pediatrics, and NICE guidelines all prioritize FDA-approved stimulants due to their superior efficacy and extensive evidence base. 3, 4
Non-stimulant alternatives like atomoxetine, extended-release guanfacine, or extended-release clonidine are recommended as second-line options when stimulants fail or are contraindicated. 3, 4, 5
L-Theanine Dosing Evidence (Research-Based Only)
Since L-theanine lacks guideline support, the following is based solely on available research studies:
Effective Dose Range
400 mg daily (divided as 200 mg twice daily) demonstrated the most consistent benefits in children with ADHD, improving sleep quality with higher sleep percentage and efficiency scores. 2
In a proof-of-concept neuroimaging study, 2.5 mg/kg of L-theanine (approximately 100-200 mg for most children) improved overall cognitive performance when measured by NIH Cognition Toolbox. 1
Dose-Response Relationship
Lower doses (100-200 mg) showed limited effects on complex attentional tasks, primarily improving only simple visuomotor reaction times by approximately 16-17 milliseconds. 6
400 mg demonstrated neurophysiological improvements in selective attention, reducing P3b latency (a measure of attentional processing speed) by approximately 16 milliseconds compared to placebo, with a linear dose-response of 4 ms reduction per 100 mg increase. 7
Doses below 400 mg did not significantly improve sustained attention or inhibitory control tasks in isolation. 6, 7
L-Theanine Combined with Caffeine
The combination of L-theanine (97-100 mg) with caffeine (40 mg) showed synergistic effects on sustained attention and cognitive performance that exceeded either compound alone. 1, 8
This combination improved accuracy during task switching, d-prime scores in Go/NoGo tasks, reduced mind wandering (decreased default mode network activity), and showed trends toward improved inhibitory control. 1, 8
The caffeine-theanine combination at these doses (approximately 2.5 mg/kg theanine + 2.0 mg/kg caffeine) may represent a more effective approach than L-theanine monotherapy. 1
Critical Clinical Caveats
L-theanine monotherapy showed a trend toward worsening inhibitory control (increased stop-signal reaction time) in one study, raising concerns about using it as monotherapy for core ADHD symptoms. 1
The evidence base consists of small proof-of-concept studies (n=5 to n=98) with short-term outcomes only, lacking the robust, large-scale, long-term efficacy and safety data that support FDA-approved ADHD medications. 1, 6, 7, 2
No established guidelines recommend L-theanine for ADHD treatment, and it should not delay or replace evidence-based pharmacotherapy with stimulants or approved non-stimulants. 3, 4
Practical Implementation (If Pursued)
If L-theanine is considered despite lack of guideline support:
Start with 400 mg daily (200 mg twice daily) based on the strongest evidence for ADHD-related outcomes, particularly for sleep quality improvements in children. 2
Consider the L-theanine-caffeine combination (100 mg L-theanine + 40 mg caffeine) if targeting sustained attention and cognitive performance, though caffeine use in children requires careful consideration. 1, 8
Monitor for potential worsening of inhibitory control, particularly with L-theanine monotherapy. 1
Reassess after 6 weeks, as this was the treatment duration in the most robust pediatric ADHD study. 2
Do not use L-theanine as a substitute for guideline-recommended treatments in patients with moderate-to-severe functional impairment requiring evidence-based pharmacotherapy. 3, 4, 5