L-Tyrosine

Semi-essential amino acid crucial for neurotransmitter synthesis, stress response, and cognitive function

Scientific nameL-Tyrosine FormulaC9H11NO3 Molecular weight181.19 g/mol CAS60-18-4

80 absorption score

7 safety / 10

20 USD per month

5 documented interactions

Check it against something

Evidence level A

L-Tyrosine with:

82 out of 100

Works better together Compatible. Timing differs, so follow each supplement's own window.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Enhanced stress response and resilience

Supports healthy stress adaptation and mental resilience

Precursor to stress-responsive catecholamine neurotransmitters Evidence A-grade 1-4 weeks

Improved cognitive performance under stress

Maintains mental clarity and focus during stressful situations

Prevents stress-induced depletion of dopamine and norepinephrine Evidence A-grade 1-2 weeks

Enhanced mental energy and alertness

Supports mental energy, focus, and cognitive function

Increases catecholamine neurotransmitter levels Evidence B-grade Days to 2 weeks

Improved mood and motivation

Supports positive mood and mental motivation

Enhances dopamine production for mood regulation Evidence B-grade 1-4 weeks

Thyroid hormone support

Essential for thyroid hormone T3 and T4 production

Required component of thyroid hormone synthesis Evidence A-grade 2-8 weeks

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Melatonin Sleep support & circadian rhythm 0.5-3mg A 50% Ashwagandha Stress management & energy 300-600mg A 75% Magnesium Glycinate Superior absorption sleep & muscle support 200-600 mg A 90% Vitamin B12 (Cyanocobalamin) Energy & nerve support 250-1000 mcg A 70% Fish Oil (EPA/DHA) Heart & brain health 1-2g EPA/DHA A 85% L-Theanine Calm focus & stress relief 100-400mg B 90%

Every pair we checked

12 combinations scored by the engine

L-Tyrosine + Creatine Monohydrate No documented interaction either way No known interaction 70

L-Tyrosine + Calcium Carbonate No documented interaction either way No known interaction 70

L-Tyrosine + Whey Protein No documented interaction either way No known interaction 70

L-Tyrosine + Lactase No documented interaction either way No known interaction 70

L-Tyrosine + Bovine Collagen No documented interaction either way No known interaction 70

L-Tyrosine + DHA No documented interaction either way No known interaction 70

L-Tyrosine + Turmeric No documented interaction either way No known interaction 70

L-Tyrosine + Fish Oil (EPA/DHA) No documented interaction either way No known interaction 70

L-Tyrosine + Caffeine Enhanced cognitive performance under stress Works better together 78

L-Tyrosine + Vitamin D3 Required for conversion to neurotransmitters Works better together 82

L-Tyrosine + Iron Sulfate Essential for tyrosine hydroxylase function Works better together 82

L-Tyrosine + Folate (5-MTHF) Required for conversion to neurotransmitters Works better together 94

Dosage

Empty stomach morning

Daily500-2000mg

Cognitive support500-1500mg daily

Stress management500-2000mg daily

Acute stress1000-3000mg (single dose)

Upper limit12g daily (medical supervision)

Before you take it

VeganYes

When to expect it

First EffectsDays to 1 week for cognitive and stress benefits

Peak Benefits2-4 weeks for sustained mental performance improvements

Deficiency DevelopmentDays to weeks during high stress or low phenylalanine

Toxicity OnsetRare, mainly blood pressure and sleep issues

How to measure it

$80-150

MarkerPlasma tyrosine levels or catecholamine metabolites

Optimal45-90 μmol/L

Deficient below<35 μmol/L

FrequencyOnly if monitoring stress response or neurotransmitter status

What people actually reported to the FDA

CAERS, 15 reports naming it as the suspect

Most reported effects

Hepatic enzyme increased 3

Malaise 2

Autoimmune hepatitis 2

Headache 2

Vision blurred 2

Named as the suspect 15 reports of 19 that mention it at all

Serious outcome 78% hospitalisation, emergency room or worse

Other Serious or Important Medical Event10

Hospitalization8

Visited a Health Care Provider6

Reports are voluntary and unverified — they record what someone experienced while taking something, not what the compound caused. Counts skew towards products people take a lot of, and a serious outcome is more likely to be reported than a mild one, so these are not rates. How we filter them →

What actually reaches you

The label counts the carrier, your body does not

Absorption Very high 80 of 100 · best absorbed form of this compound

Delivered daily 1000 mg

Cost per 100 mg delivered $0.07 comparative — uses the absorption score, not a measured percentage

Works better with

3 documented

Vitamin C

Required for conversion to neurotransmitters

Cofactor for dopamine beta-hydroxylase enzyme · level A

Iron

Essential for tyrosine hydroxylase function

Required cofactor for dopamine synthesis · level A

Folate Bh4

Required for tyrosine hydroxylase activity

Cofactor for rate-limiting enzyme in catecholamine synthesis · level A

What not to take with L-Tyrosine

2 documented

Other Large Amino Acids

Competes with phenylalanine, tryptophan for brain uptake

Shared large amino acid transporter · major significance

Protein Meals

Protein reduces tyrosine brain uptake

Competition with other amino acids · major significance

Medication interactions

Discuss these with a pharmacist before combining

monoamine-oxidase-inhibitors Major

May cause dangerous blood pressure elevation

What to do: Avoid combination or use under medical supervision

thyroid-medications Moderate

May enhance thyroid hormone effects

What to do: Monitor thyroid function

stimulant-medications Moderate

May enhance stimulant effects

What to do: Monitor for overstimulation

Available forms

bioavailability compared

L-Tyrosine (Free Form) 80

L-Tyrosine (Free Form): Stress resilience, Cognitive enhancement, Well-researched, Fast-acting

Food sources

before you supplement

Meat and poultry 0.8-1.2g per 100g · 80

Fish and seafood 0.6-1.0g per 100g · 80

Dairy products 0.4-0.8g per 100g · 75

Nuts and seeds 0.3-1.0g per 100g · 70

Too little

deficiency signs

Poor stress tolerance and mental fatigue
Depression and low motivation
Cognitive impairment and brain fog
Low blood pressure and poor stress response
Hypothyroid symptoms
Poor skin pigmentation
Reduced mental energy and alertness

Too much

toxicity signs

Generally well-tolerated:
Elevated blood pressure
Anxiety and restlessness
Insomnia and sleep disturbances
Potential thyroid overstimulation

Who benefits most

stress-management

Supports healthy stress response and mental resilience

500-2000mg daily (away from protein)

cognitive-performance

Enhances mental focus, clarity, and cognitive function

500-1500mg daily

mental-fatigue-burnout

Helps restore mental energy and reduce brain fog

1000-2000mg daily

depression-mood-support

May support mood enhancement through dopamine production

500-1500mg daily

thyroid-support

Essential for thyroid hormone production

500-1000mg daily

Where to buy it

compare forms first

Look for L-Tyrosine at 500-2000mg per serving. The form that matters here is L-Tyrosine (Free Form).

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What else affects it

Beyond other supplements

Protein meals

Protein reduces tyrosine brain uptake

Competition with other amino acids

How it works

Converted to L-DOPA and then dopamine neurotransmitter
Dopamine converted to norepinephrine and epinephrine
Essential substrate for catecholamine neurotransmitter synthesis
Required component for thyroid hormone T3 and T4 production
Important for melanin synthesis and skin pigmentation
Prevents stress-induced depletion of neurotransmitters

Key findings

what the evidence supports

Effective for maintaining cognitive performance under stress
Essential precursor to dopamine and norepinephrine
May improve mood and mental energy
Important for thyroid hormone production

Sources: NIH Examine.com PubMed 25598314 · data reviewed 2026-08-02

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of L-Tyrosine?

Documented effects: Enhanced stress response and resilience; Improved cognitive performance under stress; Enhanced mental energy and alertness; Improved mood and motivation. Supports healthy stress adaptation and mental resilience

How much L-Tyrosine should you take per day?

The common daily range is 500-2000mg. By goal — cognitive support: 500-1500mg daily; stress management: 500-2000mg daily; acute stress: 1000-3000mg (single dose); upper limit: 12g daily (medical supervision).

When is the best time to take L-Tyrosine?

Empty stomach morning. First effects are typically reported within Days to 1 week for cognitive and stress benefits.

What are the side effects of L-Tyrosine?

At excessive doses: Generally well-tolerated:, Elevated blood pressure, Anxiety and restlessness, Insomnia and sleep disturbances, Potential thyroid overstimulation. Safety rating at normal doses is 7 out of 10.

What should you not take with L-Tyrosine?

Separate it from Other Large Amino Acids, Protein Meals by two to four hours. Competes with phenylalanine, tryptophan for brain uptake

Does L-Tyrosine interact with medications?

Documented interactions with monoamine-oxidase-inhibitors, thyroid-medications, stimulant-medications. Discuss these with a pharmacist before combining.

How do you know if you need L-Tyrosine?

The marker is Plasma tyrosine levels or catecholamine metabolites, optimal range 45-90 μmol/L. Common deficiency signs: Poor stress tolerance and mental fatigue, Depression and low motivation, Cognitive impairment and brain fog, Low blood pressure and poor stress response.

Taken for

52 Brain & Focus

Caffeine · DHA · Fish Oil (EPA/DHA)

28 Sleep & Stress

Melatonin · Magnesium Glycinate · Ashwagandha