L-theanine and ADHD have a small but genuinely interesting research record: a handful of trials suggest L-theanine may support sleep quality in kids with ADHD and, paired with caffeine, attention in young people with ADHD. It is not a treatment for ADHD, and the studies are small, so treat it as a possible support alongside proper care, never a replacement for it.
Here is what the studies found, the doses they used, and how to think about L-theanine if you also take ADHD medication.
What Is L-Theanine?
L-theanine is an amino acid found mainly in tea leaves. It is the reason a cup of green tea feels calmer than a cup of coffee with similar caffeine. People take it for relaxed alertness: settled, but not sleepy.
In healthy adults, the evidence is modest but consistent. In a randomized crossover trial of 30 adults, 200mg a day for four weeks lowered scores for stress, anxiety and sleep complaints and improved verbal fluency and an executive function score compared with placebo (Hidese et al., 2019). Our full guide to L-theanine benefits covers the wider picture.
What the Research on L-Theanine and ADHD Shows
The ADHD-specific research is thin. Three studies do most of the work.
Sleep in Boys With ADHD
The biggest trial gave 98 boys aged 8 to 12 with diagnosed ADHD either 400mg of L-theanine a day (two 100mg chewable tablets, twice daily) or placebo for six weeks. Wrist actigraphy showed higher sleep percentage and sleep efficiency in the L-theanine group. Time to fall asleep did not change, and the high dose was well tolerated (Lyon et al., 2011). That matters because sleep problems are common in ADHD, and poor sleep makes attention harder for everyone.
Attention When Paired With Caffeine
A tiny crossover trial in five boys with ADHD compared L-theanine, caffeine, the two together and placebo. Caffeine alone appeared to worsen a measure of impulse control. The combination improved an overall cognition score and an attention measure, and brain imaging showed reduced activity in a network linked to mind wandering (Kahathuduwa et al., 2020).
A follow-up crossover study in 21 adolescents with ADHD compared the combination with methylphenidate and placebo. Both the combination and methylphenidate reduced false alarms on an attention task. Only methylphenidate improved reaction time (Nawarathna et al., 2026). Read that honestly: an interesting signal, a very small study, and no evidence of equivalence to medication.
The pairing has a longer track record in adults without ADHD. In 27 healthy volunteers, 100mg L-theanine with 50mg caffeine improved speed and accuracy on an attention-switching task and reduced distraction on a memory task (Owen et al., 2008). We dig into ratios in our L-theanine and caffeine focus stack guide.
What the Reviews Conclude
A 2024 systematic review of 11 randomized trials found L-theanine outperformed control conditions for symptoms in several conditions, ADHD included, while calling for more research (Moshfeghinia et al., 2024). A 2025 review of ADHD supplements was blunter: L-theanine improved sleep efficiency but not other sleep measures, the caffeine combination may help attention, and supplements cannot replace the well-documented efficacy of stimulants (Al Shahab et al., 2025).
L-Theanine for ADHD in Adults: What It May and May Not Do
There are no solid trials of L-theanine alone in adults with ADHD. So for adults, we are extrapolating from the kids' studies and the healthy-adult research. With that caveat, here is a fair summary.
It may help with: a calmer, steadier kind of focus, especially paired with a moderate amount of caffeine; winding down and sleep quality; and smoothing out the jittery edge of caffeine.
It does not: treat inattention, impulsivity or hyperactivity as a condition, replace medication or therapy, or work like a stimulant. If you are stuck on starting tasks, the behavioral tools in our ADHD paralysis guide will do more than any supplement.
If you are comparing options, our roundup of the best supplements for ADHD covers the evidence for others, and our piece on L-tyrosine for ADHD looks at the dopamine-precursor angle.
Doses Used in the Studies
There is no official ADHD dose, because L-theanine is not an ADHD treatment. These are the amounts researchers actually used.
| Study | Who | Dose | What Changed |
|---|---|---|---|
| Lyon et al., 2011 | 98 boys with ADHD, aged 8 to 12 | 400mg a day for 6 weeks | Better sleep percentage and efficiency; no change in time to fall asleep |
| Kahathuduwa et al., 2020 | 5 boys with ADHD | Single dose, 2.5mg/kg L-theanine with 2.0mg/kg caffeine | Better overall cognition score and attention measure vs placebo |
| Nawarathna et al., 2026 | 21 adolescents with ADHD | Single high dose of L-theanine with caffeine | Fewer false alarms; no reaction time gain |
| Hidese et al., 2019 | 30 healthy adults | 200mg a day for 4 weeks | Lower stress, anxiety and sleep complaint scores |
| Owen et al., 2008 | 27 healthy adults | 100mg L-theanine with 50mg caffeine | Faster, more accurate attention switching |
For adults, most daily use falls in the 100mg to 400mg range seen in these trials. Start at the lower end and see how you feel.
L-Theanine and ADHD Medication
Direct research on combining L-theanine with ADHD medication is limited. In the Lyon trial, some boys were on stimulant medication and some were not, and no significant adverse events were reported. That is reassuring, but it is one study in children.
Some adults use L-theanine to take the edge off stimulant side effects, like feeling wired or struggling to wind down at night. That is a real reason people try it, but it has not been tested in a trial we know of. Sleep is worth raising with your prescriber either way: insomnia is a commonly reported side effect in stimulant trials (Wynchank et al., 2017).
The rules are simple. Tell your prescriber before adding any supplement. Never stop, skip or adjust medication on your own. And if your L-theanine comes with caffeine, count that caffeine, because it stacks with stimulant medication.
L-Theanine for Kids With ADHD
The child studies above are encouraging, but they are small and short. If you are considering L-theanine for your child, talk to your pediatrician first. They can check it against any medication and help you pick a form and dose made for children.
To be clear, our mints are formulated for adults. FOCUS+FLOW contains caffeine and is not for kids. If you are the parent with ADHD in the house, our guide for the ADHD mom is written for you.
Where Our Mints Fit
We sell two products that contain L-theanine, so weigh this section accordingly.
FOCUS+FLOW is our daytime mint. Each one has 150mg L-theanine with 100mg caffeine, the same pairing studied above, plus 100mg L-tyrosine, 100mg rhodiola rosea, 100mg CognatiQ (coffee fruit extract), 18mg citicoline, 5.1mg vitamin B6 and 60mcg vitamin B12. It is sublingual, so most people feel it in about 15 minutes.
CALM+COLLECTED is the caffeine-free option. Each mint has 200mg L-theanine with 200mg lemon balm, 100mg holy basil, 120mg magnesium glycinate and 20mcg vitamin D. It is non-drowsy, so it works in the evening, on a stimulant-medication day when you do not want more caffeine, or any time you want calm without the lift. Full details are on the CALM+COLLECTED page.
Neither treats ADHD. Keep total caffeine under about 400mg a day, the level the FDA cites for most healthy adults. If you take ADHD medication, check with your prescriber first. If you are pregnant or breastfeeding, check with your doctor first. Both are non habit-forming, $59 for 24 mints or $39 on subscription, with a 30-day money-back guarantee.
CALM FOCUS, BUILT ON L-THEANINE
150mg L-theanine with 100mg caffeine, in a mint you feel in about 15 minutes.
SHOP FOCUS+FLOWKey Takeaways
- L-theanine is not an ADHD treatment, but small trials suggest it may support sleep and, with caffeine, attention.
- The best ADHD data are in children: 400mg a day improved sleep efficiency in 98 boys, and small studies found the caffeine pairing helped some attention measures.
- Studied doses range from about 100mg to 400mg a day. There is no established ADHD dose.
- If you take ADHD medication, talk to your prescriber first and count any added caffeine.
- For kids, start with the pediatrician. Our mints are for adults.
Explore the Series
- ADHD Paralysis: Why You Freeze and How to Get Moving Again
- ADHD Mom: Why Motherhood Turns Up the Volume and What Helps
- L-Theanine Benefits, Explained
- The Best Supplements for ADHD
- L-Tyrosine for ADHD
- Sublingual L-Theanine
References
- Lyon MR, et al. The effects of L-theanine (Suntheanine) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev. 2011. PMID 22214254
- Kahathuduwa CN, et al. Effects of L-theanine-caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT. Sci Rep. 2020. PMID 32753637
- Nawarathna GS, et al. Effects of L-theanine-caffeine combination on selective attention among adolescents with attention-deficit hyperactivity disorder: a double-blind, placebo-controlled, crossover study. Nutr Neurosci. 2026. PMID 42096377
- Owen GN, et al. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci. 2008. PMID 18681988
- Hidese S, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: a randomized controlled trial. Nutrients. 2019. PMID 31623400
- Moshfeghinia R, et al. The effects of L-theanine supplementation on the outcomes of patients with mental disorders: a systematic review. BMC Psychiatry. 2024. PMID 39633316
- Al Shahab S, et al. Efficiency of different supplements in alleviating symptoms of ADHD with or without the use of stimulants: a systematic review. Nutrients. 2025. PMID 40362791
- Wynchank D, et al. Adult attention-deficit/hyperactivity disorder (ADHD) and insomnia: an update of the literature. Curr Psychiatry Rep. 2017. PMID 29086065
FAQ
Does L-Theanine Help ADHD?
It does not treat ADHD, but small studies suggest it may help with parts of the picture. In boys with ADHD, 400mg a day improved sleep efficiency, and in small trials L-theanine paired with caffeine improved some attention measures. Larger studies, especially in adults, are still needed.
How Much L-Theanine Should I Take for ADHD?
Studies in this area have used roughly 100mg to 400mg a day, depending on the population and the goal. There is no established ADHD dose, because L-theanine is not an ADHD treatment. Start at the low end and talk to your clinician, especially if you take medication.
Can I Take L-Theanine With ADHD Medication?
Many people do, but direct research on the combination is limited, so ask your prescriber first. Never change your medication on your own. If your L-theanine product also contains caffeine, count it, because caffeine adds to the effect of stimulant medication.
Is L-Theanine Safe for Kids With ADHD?
A six-week trial in boys aged 8 to 12 found 400mg a day well tolerated, with no significant adverse events. That is one study, so talk to your pediatrician before giving it to a child. Products with caffeine, including our mints, are not for kids.
Should I Take L-Theanine in the Morning or at Night?
Either can make sense. Paired with caffeine in the morning, it supports calm focus. On its own in the evening, it may help you wind down, which is why a caffeine-free option like CALM+COLLECTED suits later in the day.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. FOCUS+FLOW contains 100mg caffeine per mint and is intended for adults; if you take prescription medication or are pregnant or breastfeeding, talk to your doctor before use.
