Research review
Does L-tyrosine help with ADHD? What the research does and doesn't show
No controlled trial has tested L-tyrosine supplementation specifically in people with ADHD. A 2016 study found children with ADHD have normal blood tyrosine levels, and its authors said their results don't support treating ADHD with an amino acid supplement.
No controlled trial we found has tested L-tyrosine supplementation specifically in people with ADHD. The closest available research measured blood tyrosine levels in children with ADHD and found nothing unusual to correct — and its own authors said the results don't support treating ADHD with an amino acid supplement.
What the evidence doesn't support
It doesn't support L-tyrosine as a treatment for ADHD, in adults or children. No trial has given tyrosine to a diagnosed ADHD population and measured ADHD symptoms as an outcome. The rationale some people use as a reason to take it — tyrosine feeds the production of dopamine and norepinephrine, and dopamine signaling is implicated in ADHD — is a real biochemical fact, not a tested effect; a mechanism explaining why something might work is not the same as a trial showing that it does.
What the trials found
A 2016 study measured blood-spot and urine amino acid levels, plus dietary protein intake, in 83 children with ADHD (ages 6-13) and 72 typically developing children. The children with ADHD had normal tyrosine, tryptophan and phenylalanine levels and normal dietary protein intake compared with the control group, and amino acid levels didn't correlate with ADHD symptom severity or with comorbid conditions. The study's authors concluded that amino acid deficiencies aren't related to ADHD in this sample, and that their results don't support treatment with amino acid supplements in children with ADHD — the opposite of a rationale for supplementing tyrosine to correct a shortfall, because no shortfall was found.
Separately, tyrosine's own research base — reviewed in full at L-tyrosine benefits: what the research does and doesn't show — is built around short-term cognitive performance in healthy adults under acute stress: noise exposure, one night of sleep loss, cold-and-altitude exposure, and multi-day military training. Those trials measured working memory, vigilance and psychomotor tasks during a specific stressor, not attention or hyperactivity symptoms in an ADHD population, and a 2015 review of this literature described tyrosine's potential for clinical disorders generally as limited, while noting its cognitive effects showed up mainly when dopamine or norepinephrine activity was already being depleted by stress — a different situation from an ADHD diagnosis.
Questions people ask
Does L-tyrosine help with ADHD?
No controlled trial has tested it in an ADHD population, so there's no direct evidence either way. The one relevant study found children with ADHD don't have lower tyrosine levels than other children, which undercuts the "correct a deficiency" rationale some marketing uses.
How much L-tyrosine should I take for ADHD?
There's no dose to recommend for ADHD specifically, because no trial has tested it in that population. L-tyrosine dosage covers what doses have been tested for other outcomes, none of them ADHD.
Can you take L-tyrosine with ADHD medication?
No dedicated trial has tested L-tyrosine combined with a stimulant medication. Because tyrosine feeds the same catecholamine pathway several ADHD medications act on, that's a mechanism-based reason for caution, not a tested interaction — ask a doctor before combining them. See L-tyrosine and medications: what to check.
Is L-tyrosine good for focus in general, even without ADHD?
Tyrosine's trials found improved performance on specific cognitive tasks during acute stress in healthy adults — not a general, everyday focus effect in people who aren't under that kind of stress. See L-tyrosine benefits for what was actually measured.
When to talk to a doctor
ADHD is a diagnosis a doctor makes and manages, not something a supplement search substitutes for. L-tyrosine is not a treatment for ADHD. If you or your child take a stimulant medication or any other prescription, ask a doctor before adding L-tyrosine or any other supplement.
Related reading: L-tyrosine benefits: what the research does and doesn't show, L-tyrosine dosage, and L-tyrosine and medications: what to check.
Sources
- No Tryptophan, Tyrosine and Phenylalanine Abnormalities in Children with Attention-Deficit/Hyperactivity Disorder A 2016 study measuring blood and urine tyrosine (and related amino acid) levels in 83 children with ADHD found them normal compared with 72 typically developing children, with no link between amino acid levels and ADHD symptoms — the authors said their results don't support treating ADHD with an amino acid supplement.
- Tyrosine, phenylalanine, and catecholamine synthesis and function in the brain A 2007 review explains that tyrosine is the metabolic precursor of the catecholamine neurotransmitters dopamine, norepinephrine and epinephrine, with the effect concentrated in neurons that are actively firing — a proposed mechanism, not a measurement of what a supplement does in a person.
- Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands--A review A 2015 review concluded oral tyrosine has limited potential for clinical disorders and minimal benefit for physical exercise, but can enhance cognitive performance in short, stressful or cognitively demanding situations — specifically when dopamine or norepinephrine has been temporarily depleted, not as a general everyday effect.
*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.