Tyrosine

Sold for focus, stress and “dopamine support”. In the only ADHD study the early benefit was gone within 6 weeks in every person.

At a glance

Our verdict	The only ADHD study lost its benefit within 6 weeks; can raise blood pressure with MAOI antidepressants.
Sold for	Focus and ADHD (claimed)
How sure the evidence is	Very low
Cost a month	About $10 to $20 (estimated)

Written for adults in Canada. It explains the evidence; it is not advice for you personally. Last reviewed 20 October 2026.

Supplement Check

Is it right for you?

Tyrosine can raise blood pressure with some antidepressants and adds to stimulant medicines. Your check looks at every medicine you take and tells you what is worth doing for focus. Our Supplement Check looks at:

An MAOI now or in the last 14 days
Phenylketonuria (PKU)
Overactive thyroid
Melanoma (a theoretical concern, often listed)
Bipolar disorder
Every medicine you take

Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.

$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check

Tell me when it opens

What it is

L-tyrosine is an amino acid that the body makes from phenylalanine. It is sold for focus, stress and “dopamine support”.

Structure of Tyrosine — Structure: PubChem (public domain).

How it acts

Tyrosine is the building block for dopamine and noradrenaline. The step that turns it into them is normally running at full capacity, so extra tyrosine raises production only when nerve cells are firing hard or have been run down. That is mechanism, and it fits the evidence: a brief effect under strain, not a lasting one.

Outline of a person showing where Tyrosine acts in the body

What it is used for, and what the evidence says

Use	What the trials found	How sure we are
Adults with ADHD	An open 8-week trial (no placebo) in 12 adults: 8 improved markedly or moderately at 2 weeks, and all 8 had lost the benefit by 6 weeks. [1] There is no randomised trial.	Very low
Healthy people under acute strain	A review found benefit only when the body's supply was temporarily run down: cold, sleep loss or multitasking, with single doses of 100 to 150 mg per kg taken before a demanding task. [2]	Very low

How sure we are: High means further research is very unlikely to change the answer; Moderate, it might; Low, it may well change; Very low, we are very unsure. These follow the GRADE method that guideline panels use.

Benefits

A brief, situational effect in healthy people under acute strain. [2]
None lasting in ADHD. [1]

Risks and side effects

Common: nausea, headache, trouble sleeping.
High blood pressure with MAOI antidepressants.

Interactions with medicines

Our review found no report that it speeds up or blocks the liver enzymes that clear medicines; that question has not been studied for it.

Medicine	What can happen	What to do
MAOI antidepressants and related medicines, now or in the last 14 days: phenelzine, tranylcypromine, moclobemide, selegiline, rasagiline, safinamide, linezolid, methylene blue	Rise in blood pressure	Do not take
Levodopa (for Parkinson disease)	Competes with it for entry into the brain	Do not take
Thyroid hormone (levothyroxine)	Tyrosine is a building block of thyroid hormone (theoretical)	Discuss with your doctor
ADHD stimulants and atomoxetine	Adds to the same nerve messengers; never tested	Do not take

Who should not take it

An MAOI now or in the last 14 days.
Phenylketonuria (PKU): tyrosine is not harmful in PKU (it is often prescribed), but the metabolic clinic sets the amount, not us.
Overactive thyroid.
Melanoma (a theoretical concern, often listed).
Bipolar disorder.
Tyrosinaemia.
Pregnancy and breastfeeding (no data).
Anyone on a stimulant or atomoxetine.
Under 18: outside the Supplement Check.

Dose and timing

We do not recommend a dose. For reference, studies used 500 to 2,000 mg a day; the ADHD trial used up to 50 to 100 mg per kg; studies under acute strain used single doses of 100 to 150 mg per kg before the task.

What we know about Canadians

Canada has no measured national figure for ADHD (attention deficit hyperactivity disorder) in adults. Worldwide, about 2.6% of adults have ADHD that began in childhood and 6.8% have the symptoms. [3] Diagnosis and treatment in adults have risen sharply: in Ontario, new stimulant prescriptions rose 157% from 2015 to 2023, with the steepest rises in women aged 25 to 44 (up 421%) and 18 to 24 (up 369%). [4] In British Columbia, new adult diagnoses went from about 9 to 35 per 100,000 a month between before and after the pandemic. [5]

Most at risk of being newly diagnosed or treated: women aged 18 to 44. With so many more adults on stimulant medicines, what is taken alongside them matters more.

No Canadian data on tyrosine use in our review.

How sure are we: low. Low for how many Canadian adults have ADHD (a global estimate); high for the rise in prescribing (whole-population Ontario and British Columbia data).

An honest comparison: adult ADHD symptoms

Effect sizes are put on one common scale so that different symptom questionnaires can be compared: the bigger the number, the more symptoms fell compared with a dummy pill (placebo). The medicine figures come from blinded trials in adults, rated by clinicians at about 12 weeks; the self-rated figures are closer to what you would notice yourself.

Option	Effect	How sure we are	Cost a month (CAD)
L-tyrosine	No randomised trial; early benefit lost by 6 weeks in an open trial of 12 adults [1]	Very low	$10 to $20 (estimated)
Aerobic exercise, 20 to 45 minutes most days	Core symptoms improved a small amount after a single session (effect size 0.23); results of longer programmes were mixed [6]	Low	$0 to $60 (gym)
Lisdexamfetamine and other amphetamines	Clinician-rated effect size 0.79, the largest of any treatment [7]; self-rated 0.39 (stimulants as a group) [8]	Moderate to High	$90 to $150 (estimated; generic lower)
Methylphenidate, long-acting	Clinician-rated effect size 0.49 [7]	Moderate to High	$45 to $75 (estimated)
Atomoxetine (non-stimulant)	Clinician-rated effect size 0.45 [7]; self-rated 0.38 [8]	Moderate	$45 to $60 (estimated)

Why we don't recommend it

We do not sell tyrosine and our check never recommends it for focus.

Already taking it? Stop it if you take an MAOI antidepressant, a stimulant or atomoxetine, and tell your doctor. Otherwise there is no lasting benefit to pay for. If you take a stimulant or atomoxetine: check your blood pressure and pulse within 2 weeks of starting any new supplement, and tell your prescriber about every supplement you take. If a questionnaire suggests ADHD, that is a screen, not a diagnosis: it needs a formal assessment. If ADHD is confirmed, the prescription medicines reduce symptoms two to four times more than any supplement.

Tyrosine is the building block for dopamine, but the only ADHD study was a small open trial in which the early benefit disappeared within 6 weeks in every person; [1] in healthy people it helps only briefly under acute stress or sleep loss. [2] It can raise blood pressure with some antidepressants (MAOIs) and is a poor use of $10 to $20 a month. If focus is the problem, regular exercise, sleep and, where ADHD is diagnosed, the proven medicines do far more.