L-Tyrosine

Also known as: tyrosine, 4-hydroxyphenylalanine, L-Tyr

Evidence under review. — Not yet rated

Amino acid precursor to dopamine and norepinephrine. May support focus under stress.

What it does

L-Tyrosine is an amino acid your body uses to make dopamine, norepinephrine, and adrenaline — chemicals that drive focus, alertness, and stress response. Clinical trials suggest a single dose of...
Evidence quality

Evidence base hasn't been formally rated yet. See research below.
Clinical dose

2000 mg single dose (based on available study data)
Found in

1.M.R OG Pre-Workout Formula, Augustinus Bader The Hair Revitalizing Complex, Gold Standard Pre-Workout and 17 more

What the Science Says

L-Tyrosine is an amino acid your body uses to make dopamine, norepinephrine, and adrenaline — chemicals that drive focus, alertness, and stress response. Clinical trials suggest a single dose of around 2000 mg may help maintain cognitive performance, particularly reducing missed responses during demanding mental tasks. One study also found it may lower physiological arousal and speed up decision-making without hurting accuracy.

What It Doesn't Do

Won't eliminate stress or anxiety — studies show it doesn't reduce salivary stress markers or heart rate during acute stress. Not a proven endurance booster on its own. No evidence it builds muscle or burns fat. Don't expect dramatic mood improvements from a single dose.

Evidence-Based Benefits

May reduce missed responses during demanding cognitive tasks like the Stroop test.

Weak Evidence

Effective at: 2000 mg single dose

Supporting studies (click to view on PubMed):

PMID 38975711

A single 2g dose may speed up decision-making without reducing accuracy.

Weak Evidence

Effective at: 2000 mg single dose

Supporting studies (click to view on PubMed):

PMID 36548401

High-dose tyrosine may support endurance performance when mental fatigue is a factor.

Weak Evidence

Effective at: 300 mg/kg body weight

Supporting studies (click to view on PubMed):

PMID 41818465

Absorption & Bioavailability

Unknown from provided studies — no pharmacokinetic data reported in the available papers

Red Flags to Watch For

Very high doses used in some studies (300 mg/kg body weight) — far above typical supplement serving sizes
Most cognitive benefits are modest and task-specific; don't expect broad mental enhancement
People with thyroid conditions or taking thyroid medications should consult a doctor before use
Limited long-term safety data from the provided studies — all trials were acute single-dose designs

Supplement

Misleading

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Frequently Asked Questions

What does L-Tyrosine do?

Amino acid precursor to dopamine and norepinephrine. May support focus under stress.

What is the effective dose of L-Tyrosine?

2000 mg single dose (based on available study data)

Is L-Tyrosine safe?

Very high doses used in some studies (300 mg/kg body weight) — far above typical supplement serving sizes

What doesn't L-Tyrosine do?

Won't eliminate stress or anxiety — studies show it doesn't reduce salivary stress markers or heart rate during acute stress.

Research Sources

PubMed
NIH DSLD

This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25