L-tyrosine

Tyrosine/Drug Interactions:

  • Antianxiety agentsAntianxiety agents: According to secondary sources, administration of L-tyrosine may result in overstimulation, restlessness, anxiety, and insomnia.
  • AntiarrhythmicsAntiarrhythmics: According to secondary sources, heart palpitations or arrhythmias may occur following high doses of tyrosine (>500mg); however, these adverse events may occur in sensitive individuals at doses as low as 200-500mg. In humans, tyrosine supplementation increased heart rate (8).
  • AntidiabeticsAntidiabetics: According to secondary sources, supplementation with tyrosine may increase tyrosine levels in individuals using diabetic medications.
  • AntidiarrhealsAntidiarrheals: According to secondary sources, supplementation with tyrosine may cause gas, diarrhea, nausea, vomiting, or heartburn.
  • AntiemeticsAntiemetics: According to secondary sources, supplementation with tyrosine may cause gas, diarrhea, nausea, vomiting, or heartburn.
  • Antihypertensive agentsAntihypertensive agents: In humans, tyrosine supplementation decreased systolic blood pressure (6; 7) and, in another study, increased heart rate and blood pressure (8).
  • Antiseizure agentsAntiseizure agents: According to secondary sources, tyrosine deficiency may trigger seizures.
  • Antiulcer and gastric acid-reducing agentsAntiulcer and gastric acid-reducing agents: According to secondary sources, supplementation with tyrosine may cause gas, diarrhea, nausea, vomiting, or heartburn.
  • Cytochrome P450 inhibitorsCytochrome P450 inhibitors: According to secondary sources, tyrosine may interact with cytochrome P450 2D6 inhibitors.
  • Dermatologic agentsDermatologic agents: According to secondary sources, increased levels of tyrosine may cause painful hyperkeratotic plaques on the soles and palms.
  • DexamethasoneDexamethasone: Administration of dexamethasone suppressed the availability of tyrosine in postpartum women (30), in patients with depression (31; 31), and in healthy controls (31).
  • LevodopaLevodopa: According to secondary sources, levodopa may interfere with the absorption of tyrosine. In human research, changes in the concentration of phenylalanine or tyrosine in cerebrospinal fluid of patients with Parkinson's disease were lacking following levodopa treatment (32).
  • Monoamine oxidase inhibitors (MAOIs)Monoamine oxidase inhibitors (MAOIs): Tyrosine may cause a hypertensive crisis in individuals taking MAOIs, according to secondary sources.
  • NitisinoneNitisinone: According to secondary sources, nitisinone may prevent the breakdown of tyrosine in the body.
  • Ophthalmic agentsOphthalmic agents: According to secondary sources, elevated levels of tyrosine may cause vision changes, such as corneal ulcers, corneal opacities, keratitis, conjunctivitis, eye pain, and photophobia.
  • Oral contraceptivesOral contraceptives: In oral contraceptive users, the ratio of tyrosine to competing amino acids decreased, indicating decreased brain tyrosine concentrations (33).
  • Seizure threshold-lowering drugsSeizure threshold-lowering drugs: According to secondary sources, tyrosine deficiency may trigger seizures.
  • SSRIsSSRIs: Dopamine and norepinephrine are thought to play a role in depression, where a deficiency in these neurotransmitters (with serotonin) may potentiate depressive symptoms. Studies have been performed in depressed patients that involved treatment with dopamine and norepinephrine precursors such as tyrosine and L-phenylalanine (34; 35; 36; 7; 2). Serotonin and dopamine synthesis were both increased after administration of tryptophan and tyrosine; however, the effects of tyrosine alone are unclear (37).
  • StimulantsStimulants: According to secondary sources, administration of L-tyrosine may result in overstimulation, restlessness, anxiety, and insomnia.
  • Thyroid hormonesThyroid hormones: Tyrosine is a precursor to thyroxine, a thyroid hormone, and therefore, theoretically, supplementation with tyrosine may increase thyroxine levels. Following tyrosine administration in adults with normal thyroid function in Antarctica during the summer, thyroid-stimulating hormone (TSH) decreased by 30%, while in the winter, TSH decreased by 28% and serum-free triiodothyronine (fT3) increased by 6% (24).

    • Tyrosine/Herb/Supplement Interactions:

  • Amino acidsAmino acids: According to secondary sources, tyrosine is a nonessential amino acid produced from phenylalanine. Individuals unable to properly process phenylalanine and synthesize tyrosine may use protein supplements containing tyrosine, therefore theoretically increasing tyrosine levels.
  • Antianxiety agentsAntianxiety agents: According to secondary sources, administration of L-tyrosine may result in overstimulation, restlessness, anxiety, and insomnia.
  • AntiarrhythmicsAntiarrhythmics: According to secondary sources, heart palpitations or arrhythmias may occur following high doses of tyrosine (>500mg); however, these adverse events may occur in sensitive individuals at doses as low as 200-500mg. In humans, tyrosine supplementation increased heart rate (8).
  • AntidiabeticsAntidiabetics: According to secondary sources, supplementation with tyrosine may increase tyrosine levels in individuals using diabetic medications.
  • AntidiarrhealsAntidiarrheals: According to secondary sources, supplementation with tyrosine may cause gas, diarrhea, nausea, vomiting, or heartburn.
  • AntiemeticsAntiemetics: According to secondary sources, supplementation with tyrosine may cause gas, diarrhea, nausea, vomiting, or heartburn.
  • AntihypertensivesAntihypertensives: In humans, tyrosine supplementation decreased systolic blood pressure (6; 7) and, in another study, increased heart rate and blood pressure (8).
  • Antiseizure agentsAntiseizure agents: According to secondary sources, tyrosine deficiency may trigger seizures.
  • Antiulcer and gastric acid-reducing agentsAntiulcer and gastric acid-reducing agents: According to secondary sources, supplementation with tyrosine may cause gas, diarrhea, nausea, vomiting, or heartburn.
  • AspartameAspartame: According to secondary sources, aspartame contains phenylalanine, which is metabolized into tyrosine.
  • CalciumCalcium: A combination of capsaicin, green tea extract (catechins and caffeine), tyrosine, and calcium increased 24-hour energy expenditure by 160kJ daily (95% CI: 15-305) in overweight men (38); however, the effects of tyrosine alone are unclear.
  • CapsaicinCapsaicin: A combination of capsaicin, green tea extract (catechins and caffeine), tyrosine, and calcium increased 24-hour energy expenditure by 160kJ daily (95% CI: 15-305) in overweight men (38); however, the effects of tyrosine alone are unclear.
  • CopperCopper: According to secondary sources, copper may maximize the absorption of tyrosine into the body.
  • Cytochrome P450 inhibitorsCytochrome P450 inhibitors: According to secondary sources, tyrosine may interact with cytochrome P450 2D6 inhibitors.
  • Dermatologic agentsDermatologic agents: According to secondary sources, increased levels of tyrosine may cause painful hyperkeratotic plaques on the soles and palms.
  • Folic acidFolic acid: According to secondary sources, folic acid may maximize the absorption of tyrosine into the body.
  • Green teaextractGreen teaextract: A combination of capsaicin, green tea extract (catechins and caffeine), tyrosine, and calcium increased 24-hour energy expenditure by 160kJ daily (95% CI: 15-305) in overweight men (38); however, the effects of tyrosine alone are unclear.
  • Monoamine oxidase inhibitors (MAOIs)Monoamine oxidase inhibitors (MAOIs): Tyrosine may cause a hypertensive crisis in individuals taking MAOIs, according to secondary sources.
  • Ophthalmic agentsOphthalmic agents: According to secondary sources, elevated levels of tyrosine may cause vision changes, such as corneal ulcers, corneal opacities, keratitis, conjunctivitis, eye pain, and photophobia.
  • Oral contraceptivesOral contraceptives: In oral contraceptive users, the ratio of tyrosine to competing amino acids decreased, indicating decreased brain tyrosine concentrations (33).
  • PhenylalaninePhenylalanine: Phenylalanine is converted into tyrosine in the body.
  • Seizure threshold-lowering drugsSeizure threshold-lowering drugs: According to secondary sources, tyrosine deficiency may trigger seizures.
  • SSRIsSSRIs: Dopamine and norepinephrine are thought to play a role in depression, where a deficiency in these neurotransmitters (with serotonin) may potentiate depressive symptoms. Studies have been performed in depressed patients that involved treatment with dopamine and norepinephrine precursors such as tyrosine and L-phenylalanine (34; 35; 36; 7; 2). Serotonin and dopamine synthesis both increased after administration of tryptophan and tyrosine; however, the effects of tyrosine alone are unclear (37).
  • StimulantsStimulants: According to secondary sources, administration of L-tyrosine may result in overstimulation, restlessness, anxiety, and insomnia.
  • Thyroid agentsThyroid agents: Tyrosine is a precursor to thyroxine, a thyroid hormone, and therefore, theoretically, supplementation with tyrosine may increase thyroxine levels. Following tyrosine administration in adults with normal thyroid function in Antarctica during the summer, thyroid-stimulating hormone (TSH) decreased by 30%, while in the winter, TSH decreased by 28% and serum-free triiodothyronine (fT3) increased by 6% (24).
  • Vitamin B6Vitamin B6: According to secondary sources, vitamin B6 may maximize the absorption of tyrosine into the body.

    • Tyrosine/Food Interactions:

  • Calcium-containing foodsCalcium-containing foods: A combination of capsaicin, green tea extract (catechins and caffeine), tyrosine, and calcium increased 24-hour energy expenditure by 160kJ daily (95% CI: 15-305) in overweight men (38); however, the effects of tyrosine alone are unclear.
  • Green teaGreen tea: A combination of capsaicin, green tea extract (catechins and caffeine), tyrosine, and calcium increased 24-hour energy expenditure by 160kJ daily (95% CI: 15-305) in overweight men (38); however, the effects of tyrosine alone are unclear.
  • ProteinProtein: Secondary sources suggest avoiding concomitant intake of tyrosine with proteins such as milk, meat, fish, and eggs.

    • Tyrosine/Lab Interactions:

  • Blood pressureBlood pressure: In humans, tyrosine supplementation decreased systolic blood pressure (6; 7) and, in another study, increased heart rate and blood pressure (8).
  • Heart rate/rhythmHeart rate/rhythm: According to secondary sources, heart palpitations or arrhythmias may occur following high doses of tyrosine (>500mg); however, these adverse events may occur in sensitive individuals at doses as low as 200-500mg. In humans, tyrosine supplementation increased heart rate (8).
  • Thyroid-stimulating hormone (TSH)Thyroid-stimulating hormone (TSH): Following tyrosine administration in adults with normal thyroid function in Antarctica during the summer, TSH decreased by 30%, while in the winter, TSH decreased by 28% and serum-free triiodothyronine (fT3) increased by 6% (24).