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L-Tyrosine Side Effects & Safety

Evidence:Moderate
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Generally Safe

Potential Side Effects

  • Very well tolerated
  • Mild headache in rare cases
  • Possible GI discomfort at high doses
  • May cause anxiety or overstimulation in susceptible individuals

Drug & Supplement Interactions

  • MAOIs — contraindicated; excessive catecholamine accumulation risk
  • Levodopa — tyrosine competes with levodopa for brain transport
  • Thyroid medications — tyrosine is a thyroid hormone precursor; monitor thyroid levels

Maximum Dose

Do not exceed: 12 g/day (150 mg/kg) has been used in military studies; 2 g/day is typical for supplements

Full L-Tyrosine Guide

References

  1. RCTMahoney CR, Castellani J, Kramer FM, et al. (2007). Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiology & Behavior. DOI PubMed
  2. ReviewJongkees BJ, Hommel B, Kühn S, Colzato LS (2015). Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands — a review. Journal of Psychiatric Research. DOI PubMed
  3. Diao W, Su D, Cao Y, Jia Z (2022). The diagnostic accuracy of O-(2-18F-fluoroethyl)-L-tyrosine parameters for the differentiation of brain tumour progression from treatment-related changes.. Nuclear medicine communications. DOI PubMed
  4. Spankowsky S, Arlt S, Arndt G, Heuwieser W (2011). [Validity of the use of L-Tyrosine to enhance fertility of female domestic animals. A study on the evidence from the literature].. Tierarztliche Praxis. Ausgabe G, Grosstiere/Nutztiere. PubMed
  5. RCTMcAllister MJ, Martaindale MH, Dillard CC, McCullough R (2024). Impact of L-theanine and L-tyrosine on markers of stress and cognitive performance in response to a virtual reality based active shooter training drill.. Stress (Amsterdam, Netherlands). DOI PubMed
  6. Yang X, He X, Xu S, Zhang Y, et al. (2023). Effect of Lacticaseibacillus paracasei strain Shirota supplementation on clinical responses and gut microbiome in Parkinson's disease.. Food & function. DOI PubMed
  7. Kruszewski M, Merchelski M, Kruszewski A, Tabęcki R, et al. (2022). Effects of Multi-Ingredient Pre-Workout Supplement and Caffeine on Bench Press Performance: A Single-Blind Cross-Over Study.. Nutrients. DOI PubMed
Show 5 more references
  1. RCTMathar D, Erfanian Abdoust M, Marrenbach T, Tuzsus D, et al. (2022). The catecholamine precursor Tyrosine reduces autonomic arousal and decreases decision thresholds in reinforcement learning and temporal discounting.. PLoS computational biology. DOI PubMed
  2. Lang JA, Krajek AC, Schwartz KS, Rand JE (2020). Oral L-Tyrosine Supplementation Improves Core Temperature Maintenance in Older Adults.. Medicine and science in sports and exercise. DOI PubMed
  3. RCTLang JA, Smaller KA (2017). Oral l-tyrosine supplementation augments the vasoconstriction response to whole-body cooling in older adults.. Experimental physiology. DOI PubMed
  4. Israely M, Ram A, Brandeis R, Alter Z, et al. (2017). A Double Blind, Randomized Cross-Over Trial of Tyrosine Treatment on Cognitive Function and Psychological Parameters in Severe Hospitalized Anorexia Nervosa Patients.. Israel journal of psychiatry. PubMed
  5. Jung YP, Earnest CP, Koozehchian M, Galvan E, et al. (2017). Effects of acute ingestion of a pre-workout dietary supplement with and without p-synephrine on resting energy expenditure, cognitive function and exercise performance.. Journal of the International Society of Sports Nutrition. DOI PubMed