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Amino acids & derivatives

L-Tyrosine

L-tyrosine (4-hydroxy-L-phenylalanine)

L-tyrosine is a food-derived amino acid used to make catecholamine neurotransmitters. Human studies suggest it may preserve selected cognitive performance during acute stress, sleep loss, cold, or heavy task demand, but benefits are inconsistent and are not established for routine daily focus, mood, or exercise performance. Product labels commonly sit around 500-1500 mg/day, while many experiments used larger acute doses. Short-term use appears minimal risk for generally healthy adults, though longer-term evidence remains limited.

Focus SupportStress ResilienceNeurotransmitter PrecursorIsolated CompoundEndogenous CompoundFood DerivedClinical Research
Updated July 2026/6 min read/13 citations
Prepared by the NootropicsIndex editorial team.Method: prioritize cited human research and official safety or regulatory sources; compare retailer-listed prices without endorsing products.Affiliate disclosure
01

What is it?

What L-tyrosine is

1

L-tyrosine is the naturally occurring L-form of a protein-building amino acid. The body can make it from phenylalanine, and it is also present in protein-containing foods. Supplements provide an isolated dose rather than a unique drug-like compound.

Where the evidence fits3
The best-supported use case is preserving selected cognitive functions when sleep loss, cold, or heavy task demand has already reduced performance. Reviews still rate the evidence as too limited and heterogeneous for confident general recommendations.
02

Names, aliases and forms

Chemical Name4-hydroxy-L-phenylalanine
Common Nametyrosine
AbbreviationTyr
Cas Number60-18-4
Pubchem Cid6057
Molecular FormulaC9H11NO3
03

Mechanisms of action

A precursor, not a guaranteed neurotransmitter boost

2

Tyrosine is upstream of L-DOPA and the catecholamines dopamine and norepinephrine. That pathway supports a plausible stress-context mechanism, but precursor availability does not mean every dose raises brain neurotransmission or improves performance.

04

Potential effects and evidence map

Reviews provide weak or conditional support for preserving selected cognitive outcomes during acute stressors such as sleep loss, cold, or demanding tasks. Confidence is limited by small samples, heterogeneous methods, and inconsistent outcomes. Evidence does not support broad everyday nootropic, mood-treatment, or physical-performance claims.

Effect domainMagnitudeGrade
Stress resilience3
AcuteConfidence: Medium

May preserve selected cognitive performance measures during acute stress, sleep loss, cold exposure, or unusually demanding tasks.

Note Evidence is conditional and heterogeneous; this is not a general anti-stress effect.

2/5
C
Focus / attention4
AcuteConfidence: Medium

Small trials report attention, vigilance, or cognitive-control signals mainly when performance is already challenged.

Note Routine enhancement in rested, unstressed adults is not established.

2/5
C
Memory / learning7
AcuteConfidence: Low

Some studies report working-memory benefits under stress, while dose, age, and task can change the response.

Note A dose-response trial in older adults found worse working-memory performance at higher doses.

2/5
C
Physical energy / endurance9
AcuteConfidence: Medium

No consistent physical-performance or endurance benefit has been demonstrated.

Note Reviews could not recommend it for physical performance, and a 2025 heat-exercise trial was negative.

0/5
C
Mood / wellbeing2
UnknownConfidence: Medium

Evidence does not support L-tyrosine as a treatment for depression, anxiety, or routine mood enhancement.

Note Precursor biology is not evidence of a clinical mood effect.

0/5
D
05

Typical dosages and timing

Typical
500-1500 mg/day
Not a recommendation
Lower bound
500 mg/day
Profile value
Upper bound
1500 mg/day
Profile value
shopping comparison13500-1500 mg/day

A current 500 mg capsule label suggests one capsule one to three times daily. Product directions vary, and this shopping-comparison range is not a proven effective dose or a personalized recommendation.

research context42 g or 100-150 mg/kg

Many performance experiments used a single 2 g dose or weight-based 100-150 mg/kg doses. Those protocols are not standard daily-use instructions and should not be copied without considering age, health, medicines, and the specific task setting.

06

Timing & effect horizon

Effect horizonAcute
Acute
Plasma peak3Acute
2 hours
Study task window3Acute
1-5 hours
Sleep-loss signal5Acute
3 hours
Safety RCT8Cumulative
4 weeks
Timing facts describe studies, not a guaranteed personal onset3

Plasma concentrations typically peak around two hours in the reviewed literature, and experimental task effects were assessed across roughly one to five hours. The three-hour value is the duration of selected performance signals in one sleep-loss experiment; it is not a universal effect duration.

07

Safety, side effects and risk profile

Phenelzine label warning10
Current U.S. phenelzine labeling says patients taking phenelzine should not take L-tyrosine. If you use phenelzine, follow your prescriber or pharmacist’s guidance rather than adding a concentrated tyrosine supplement.
Levodopa absorption context11
Levodopa labeling notes that certain amino acids can reduce levodopa absorption. If you take levodopa, ask your prescriber or pharmacist how concentrated amino-acid supplements fit your medicine schedule.
Evidence uncertainty8
Confidence: Medium

A four-week randomized trial found 1-4 g/day well tolerated in healthy adult men, but longer-term and broader-population safety data remain limited.

Note Minimal intrinsic risk at typical oral supplemental use; medicine-specific cautions are handled separately.

1/5
C
minimal intrinsic risk81-4 g/day for 4 weeks

In 30 healthy adult men, adverse-event rates at L-tyrosine doses up to 4 g/day were comparable with placebo, no serious adverse events occurred, and no clinically meaningful dose-related laboratory, blood-pressure, or heart-rate abnormalities were found. Evidence beyond four weeks is still limited.

08

Legal and regulatory status

United States12

L-tyrosine may be marketed in the U.S. as a dietary supplement, but FDA does not approve dietary supplements for safety or effectiveness before sale. Product claims must not present it as a treatment or prevention for depression, ADHD, thyroid disease, or another disease. Rules and market status can differ outside the U.S.

09

Practical buying and quality notes

  • Check that the label specifies L-tyrosine, record the amount per serving, and compare price per gram. N-acetyl-L-tyrosine is a different form and should not be treated as dose-for-dose equivalent. Prefer products with transparent excipients and credible independent identity and contaminant testing.1
10

FAQ

Does L-tyrosine improve focus?

4

Possibly in specific acute stress settings. Small studies report attention or vigilance benefits during sleep loss, cold, or heavy task demand, but routine focus enhancement in rested adults is not established.

How much L-tyrosine was studied?

8

The strongest recent safety evidence tested 1-4 g/day for four weeks. Cognitive experiments often used 2 g or larger weight-based acute doses, which are research protocols rather than general dosing instructions.

When was L-tyrosine tested before tasks?

3

Study designs varied. Reviews place the plasma peak near two hours and task testing across roughly one to five hours after dosing, so a universal 30-minute onset claim is not justified.

Is L-tyrosine safe?

8

For generally healthy adults, typical oral supplement use appears minimal risk. A four-week trial found up to 4 g/day well tolerated in healthy men, but longer-term data are limited and prescription-medicine situations need separate review.

Is it proven for mood or exercise performance?

9

No. Evidence does not support it as a treatment for mood disorders, and reviews plus newer trials do not show a consistent exercise-performance benefit.

11

References

  1. PubChem Compound Summary for CID 6057, L-Tyrosine. National Center for Biotechnology Information.
  2. Jongkees BJ, Hommel B, Kuhn S, Colzato LS. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands: a review. J Psychiatr Res. 2015;70:50-57.
  3. Attipoe S, Zeno SA, Lee C, Crawford C, Khorsan R, Walter AR, Deuster PA. Tyrosine for mitigating stress and enhancing performance in healthy adult humans: a rapid evidence assessment. Mil Med. 2015;180(7):754-765.
  4. Pomeroy DE, Tooley KL, Probert B, Wilson A, Kemps E. A systematic review of the effect of dietary supplements on cognitive performance in healthy young adults and military personnel. Nutrients. 2020;12(2):545.
  5. Neri DF, Wiegmann D, Stanny RR, Shappell SA, McCardie A, McKay DL. The effects of tyrosine on cognitive performance during extended wakefulness. Aviat Space Environ Med. 1995;66(4):313-319.
  6. Deijen JB, Wientjes CJE, Vullinghs HFM, Cloin PA, Langefeld JJ. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull. 1999;48(2):203-209.
  7. van de Rest O, Bloemendaal M, de Heus R, Aarts E. Dose-dependent effects of oral tyrosine administration on plasma tyrosine levels and cognition in aging. Nutrients. 2017;9(12):1279.
  8. Matsumoto H, Miura N, Naito M, Elango R. Evaluation of the safety and tolerability of L-tyrosine supplementation in healthy adult men: a randomized crossover trial. Nutrients. 2026;18(12):2020.
  9. Donnan KJ, Williams EL, Stanger N. Tyrosine supplementation is ineffective in facilitating soccer players physical and cognitive performance during high-intensity intermittent exercise in hot conditions. PLoS One. 2025;20(1):e0317486.
  10. DailyMed. Phenelzine sulfate tablets, USP: U.S. prescribing information. Updated April 2026.
  11. U.S. Food and Drug Administration. DUOPA (carbidopa and levodopa) prescribing information. 2026.
  12. U.S. Food and Drug Administration. FDA 101: Dietary Supplements.
  13. NOW Foods. L-Tyrosine 500 mg capsules: Supplement Facts and Suggested Usage.
Note

This page is informational and summarizes available evidence. It is not medical advice, a recommendation, or a substitute for guidance from a qualified clinician.