L-Tyrosine and medications.
L-Tyrosine is in the Distil supplement database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.
L-tyrosine is an amino acid the body uses to make dopamine and noradrenaline, and it is also a building block for thyroid hormones. Its main supplement use is supporting cognitive performance under stress, where the evidence is Grade B from work by Colzato and Deijen; the ADHD case is weaker at Grade C. The usual dose is 500 to 2,000mg, taken as needed before demanding tasks or daily for ADHD support, starting low if you are sensitive to stimulants. The interactions here are the cautionary part. It must be avoided entirely with MAOIs, where the combination is serious. Because it is a thyroid hormone precursor, it warrants monitoring alongside thyroid medication, and it competes with levodopa for absorption, so those should be separated. Anxiety-prone people should start at the low end, since tyrosine can worsen anxiety in some. Taken late it can disturb sleep, so earlier in the day is the practical default.
Below are the 15 documented pairs we have explicitly assessed for L-Tyrosine: 3 red and 12 amber. The pairs cluster around 5 mechanisms: MAOI pressor (blood-pressure surge), Antithyroid drug interference, Levodopa amino-acid transport competition, Additive sympathomimetic activity, and Additive thyroid-hormone effect. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
MAOI pressor (blood-pressure surge)
L-Tyrosine is the raw material your body turns into adrenaline and noradrenaline. Isocarboxazid is an irreversible MAOI that blocks the breakdown of those same chemicals. Loading extra precursor while the breakdown pathway is shut off may push blood pressure up sharply, so we treat this as a do-not-combine pair without specialist sign-off.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-Tyrosine is the raw material your body turns into adrenaline and noradrenaline. Phenelzine is an irreversible MAOI that blocks the breakdown of those same chemicals. Loading extra precursor while the breakdown pathway is shut off may push blood pressure up sharply, so we treat this as a do-not-combine pair without specialist sign-off.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-tyrosine is a building block for noradrenaline and dopamine, and tranylcypromine is an MAOI that stops these from being broken down. Together they could drive blood pressure dangerously high (a hypertensive crisis). Tranylcypromine carries the strongest pressor risk of the MAOIs, so we treat this as a do-not-combine pair without specialist sign-off.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-Tyrosine is the raw material your body turns into adrenaline and noradrenaline. Linezolid is an antibiotic that also acts as a reversible MAOI, which carries less blood-pressure risk than the older irreversible MAOIs, but adding extra precursor while that pathway is partly slowed could still nudge blood pressure up. Take this combination only with your prescriber's awareness, and not at high tyrosine doses.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-Tyrosine is the raw material your body turns into adrenaline and noradrenaline. Moclobemide is a reversible MAOI, which carries much less of the blood-pressure risk seen with the older irreversible MAOIs, but adding extra precursor while that pathway is partly slowed could still nudge blood pressure up. Take this combination only with your prescriber's awareness, and not at high tyrosine doses.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Rasagiline is a selective MAO-B inhibitor used for Parkinson's. L-Tyrosine is the raw material the body turns into noradrenaline and adrenaline. Combining a catecholamine precursor with an MAO inhibitor can in theory raise blood pressure, though the risk is lower with a selective MAO-B drug than with the older non-selective MAOIs. Raise this with your prescriber and have blood pressure checked rather than starting on your own.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Selegiline is a selective MAO-B inhibitor used for Parkinson's. L-Tyrosine is the raw material the body turns into noradrenaline and adrenaline. Combining a catecholamine precursor with an MAO inhibitor can in theory raise blood pressure, and selegiline can add its own pressor effect at higher doses. Raise this with your prescriber and have blood pressure checked rather than starting on your own.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Antithyroid drug interference
Carbimazole works by lowering an overactive thyroid. L-tyrosine is a building block of thyroid hormone and at high doses can nudge thyroid activity up, so in theory it could pull against carbimazole and make it a little less effective. This has not been tested in people on carbimazole, so it is a caution rather than a firm warning. If you take carbimazole, mention L-tyrosine to the clinician who manages your thyroid and keep to your usual thyroid blood tests.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Propylthiouracil works by lowering an overactive thyroid. L-tyrosine is a building block of thyroid hormone and at high doses can nudge thyroid activity up, so in theory it could pull against propylthiouracil and make it a little less effective. This has not been tested in people on propylthiouracil, so it is a caution rather than a firm warning. If you take propylthiouracil, mention L-tyrosine to the clinician who manages your thyroid and keep to your usual thyroid blood tests.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Levodopa amino-acid transport competition
Co-beneldopa (Madopar) contains levodopa. L-Tyrosine and levodopa are both large amino acids that share the same carrier from the gut into the blood and into the brain, so taking a tyrosine supplement around the same time may blunt how well the medication works. Separate any tyrosine supplement from your doses and discuss it with your Parkinson's team rather than adding it on your own.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Co-careldopa (Sinemet) contains levodopa. L-Tyrosine and levodopa are both large amino acids that share the same carrier from the gut into the blood and into the brain, so taking a tyrosine supplement around the same time may blunt how well the medication works. Separate any tyrosine supplement from your doses and discuss it with your Parkinson's team rather than adding it on your own.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive sympathomimetic activity
L-tyrosine is the raw material your body turns into dopamine and noradrenaline, the same brain chemicals dexamfetamine raises. Taking the two together could in theory add to a stimulant's effects, such as a faster heart rate, higher blood pressure, jitteriness or trouble sleeping, though supplemental tyrosine's effect on top of the medicine is likely to be modest. If you take a stimulant, mention any tyrosine supplement to your prescriber, start at a low dose, and keep an eye on your heart rate and how wired or restless you feel.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-tyrosine is the raw material your body turns into dopamine and noradrenaline, the same brain chemicals lisdexamfetamine raises. Taking the two together could in theory add to a stimulant's effects, such as a faster heart rate, higher blood pressure, jitteriness or trouble sleeping, though supplemental tyrosine's effect on top of the medicine is likely to be modest. If you take a stimulant, mention any tyrosine supplement to your prescriber, start at a low dose, and keep an eye on your heart rate and how wired or restless you feel.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-tyrosine is the raw material your body turns into dopamine and noradrenaline, the same brain chemicals an ADHD stimulant like methylphenidate raises. Taking the two together could in theory add to a stimulant's effects, such as a faster heart rate, higher blood pressure, jitteriness or trouble sleeping, though supplemental tyrosine's effect on top of the medicine is likely to be modest. If you take a stimulant, mention any tyrosine supplement to your prescriber, start at a low dose, and keep an eye on your heart rate and how wired or restless you feel rather than adding it on your own.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive thyroid-hormone effect
L-tyrosine is one of the building blocks your body uses to make thyroid hormone, and a high-dose study found it can gently lower TSH and nudge thyroid activity up. On top of levothyroxine that effect could in theory add up and tip you towards having a little too much thyroid hormone, though this has not been tested in people who take levothyroxine. If you take both, mention the L-tyrosine to the clinician who manages your thyroid and ask for a TSH check so your dose can be reviewed if needed.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
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