L-Tyrosine
Also known as L-Tyrosine, N-Acetyl-L-Tyrosine
Non-essential amino acid and precursor to dopamine and noradrenaline via the enzyme tyrosine hydroxylase; most consistent evidence is for preserving cognitive performance under acute stress, sleep loss, or cold exposure rather than baseline mood.
Be careful if: pregnant, breastfeeding, certain health conditions
Suspect a side effect? Report it to the MHRA Yellow Card scheme ↗
What the research actually shows
We link to relevant studies and leave interpretation to you and your healthcare professional.
Safety and considerations
What sources report about side effects, who should be careful, and medicines to ask about first.
Be careful if you…
| Applies to | What sources say | Sources |
|---|---|---|
| pregnant | No pregnancy safety guidance found in any chain source checked (no UK SmPC, BNF/NICE, NHS, NIH ODS or EMA HMPC entry exists for L-tyrosine); the reviewed trials report no pregnancy data. Not studied in pregnancy — assume nothing and ask a clinician. | Jongkees BJ, et al. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands — a review. J Psychiatr Res 2015;70:50-7 (PMID 26424423) |
| breastfeeding | No breastfeeding safety guidance found in any chain source checked (no UK SmPC, BNF/NICE, NHS, NIH ODS or EMA HMPC entry exists for L-tyrosine); no lactation data in the reviewed trials. Not studied while breastfeeding — assume nothing and ask a clinician. | Jongkees BJ, et al. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands — a review. J Psychiatr Res 2015;70:50-7 (PMID 26424423) |
| certain health conditions | Phenylketonuria: people with PKU are under specialist dietary management, and a Cochrane review found insufficient evidence to recommend routine tyrosine supplementation in PKU. Any use should go through their metabolic team. | Webster D, Wildgoose J. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev 2010;(8):CD001507 (PMID 20687067) |
Sources
Jongkees BJ, et al. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands — a review. J Psychiatr Res 2015;70:50-7 (PMID 26424423)Webster D, Wildgoose J. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev 2010;(8):CD001507 (PMID 20687067)
Suggested uses (unproven)
Where people report using it and what trials suggest
- Moderate evidenceCognitive resilience under acute stress (military/lab cold, sleep dep)
Where the evidence is negative
Common claims the trials do not support
- No benefit in rested, unstressed people.
- Depression trials (old) failed vs imipramine/placebo.
- Does not boost baseline attention or mood.
Catecholamine-precursor amino acid with specific evidence for cognition under acute, real stress (cold, sleep loss, multitasking) — not an everyday focus pill.
Evidence grades reflect study quality and consistency, not marketing claims.
Ordered by strength of evidence, then result direction.
01Levodopa and Plant-Derived Bioactive Compounds in Parkinson's Disease: Mechanisms, Efficacy, and Future PerspectivesAktaş E, et al. · CNS neuroscience & therapeutics · 2025PMID 40808332 ↗02Neurochemical and genetic factors in panic disorder: a systematic reviewMoraes ACN, et al. · Translational psychiatry · 2024PMID 39025836 ↗03Verbascoside: A neuroprotective phenylethanoid glycosides with anti-depressive propertiesZhao Y, et al. · Phytomedicine : international journal of phytotherapy and phytopharmacology · 2023PMID 37657207 ↗04The potential role of nutritional components in improving brain function among patients with Alzheimers disease: a meta-analysis of RCT studiesAlbrahim T · Neurosciences (Riyadh, Saudi Arabia) · 2020PMID 31982903 ↗05Epigenetic meta-analysis across three civilian cohorts identifies NRG1 and HGS as blood-based biomarkers for post-traumatic stress disorderUddin M, et al. · Epigenomics · 2018PMID 30456986 ↗06Stress, burnout and depression: A systematic review on DNA methylation mechanismsBakusic J, et al. · Journal of psychosomatic research · 2017PMID 27998510 ↗Show all 22 studies
Published research summaries are unavailable.
Why people look into L-Tyrosine — and what they report
Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.
Where to get L-Tyrosine (UK)
How this compound is sold in the UK, and where our readers typically find it.
Retailer search links — we may earn commission on purchases at no cost to you. Commission never affects our evidence ratings.