L-Tyrosine: Health Effects and Safety

Latest Update

L-Tyrosine Effects and Safety

Written by Meredith Worthington, Ph.D. — Medically reviewed and edited by Tod Cooperman, M.D.

Updated March 13, 2025 ⓘ

Answer:

L-tyrosine is an amino acid produced by the body from the amino acid phenylalanine (Ubaldi, Int J Mol Sci 2023; Hafid, Transl Pediatr 2015). Since it is made by the body, it is not essential.

L-tyrosine functions as a precursor of catecholamines, a group of stress-response hormones including dopamine and norepinephrine (Attipoe, Mil Med 2015; McCann, Neuropsychopharmacology 1993). L-tyrosine also serves as a precursor of melanin, a natural pigment responsible for hair, skin and eye color (Rzepka, Postepy Hig Med Dosw (Online) 2016). L-tyrosine is also used by the body to make the thyroid hormones thyroxine and triiodothyronine (Rivlin, Am J Med 1966).

Based on its functions in the body, tyrosine has been evaluated for conditions including physical and mental stress, phenylketonuria (PKU), depression, and attention deficit-hyperactivity disorder (ADHD), although clinical studies have shown its benefits to be limited, at best. Sign in as a member for details about the health benefits, as well as the safety and possible side effects of L-tyrosine.

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