What happens when you have too much tyrosine?

October 29, 2025 •

4 min read

While the body can naturally regulate its tyrosine intake, a genetic disorder called tyrosinemia or excessive supplementation can lead to a harmful buildup. When this non-essential amino acid accumulates to toxic levels, it can cause severe damage to the liver, kidneys, and nervous system.

Quick Summary

Excessive tyrosine levels in the body can be caused by rare genetic diseases called tyrosinemia or, in some cases, high doses of supplements. Symptoms range from eye and skin issues to severe liver failure, kidney damage, and neurological problems, depending on the cause and type of elevation. Management often involves a specialized diet and medication.

Key Points

Genetic vs. Supplemental Excess: High tyrosine levels can be caused by rare genetic disorders (tyrosinemia) or, less severely, from over-supplementation.
Tyrosinemia Types: There are three types of hereditary tyrosinemia, with Type I being the most severe and damaging to the liver and kidneys.
Supplement Side Effects: High doses of L-tyrosine supplements can cause side effects like nausea, headaches, and fatigue but are typically not as dangerous as tyrosinemia.
Dietary Management: A low-tyrosine diet is a key component of managing genetic tyrosinemia and is used to mitigate symptoms from high supplement intake.
Medication and Monitoring: Patients with tyrosinemia, especially Type I, often require medication like nitisinone and regular blood tests to control tyrosine levels.
Consult a Professional: Individuals with underlying health conditions, particularly thyroid or neurological disorders, should consult a doctor before taking tyrosine supplements.

What is Tyrosine and Why is it Important?

Tyrosine is a non-essential amino acid, meaning the body can produce it from another amino acid, phenylalanine. It is crucial for synthesizing several important substances, including:

Catecholamines: Neurotransmitters such as dopamine, norepinephrine, and adrenaline, which regulate mood, stress response, and focus.
Thyroid Hormones: Thyroxine, which is essential for regulating metabolism.
Melanin: The pigment responsible for skin, hair, and eye color.

Under normal circumstances, the body regulates tyrosine levels effectively. However, issues with this metabolic pathway can lead to a toxic buildup, or hypertyrosinemia.

The Dangers of Excess Tyrosine from Genetic Disorders

The most severe and life-threatening cases of too much tyrosine are caused by hereditary metabolic disorders known as tyrosinemia. These are caused by a deficiency in one of the enzymes needed to break down tyrosine, which leads to toxic byproducts accumulating in the body.

There are three main types of hereditary tyrosinemia, each with a different genetic cause and set of clinical manifestations:

Type I Tyrosinemia (HT-1): This is the most severe form, caused by a deficiency of the enzyme fumarylacetoacetate hydrolase (FAH). It typically appears in infancy and can lead to severe liver and kidney damage, liver failure, and a significantly increased risk of liver cancer if left untreated. Symptoms include failure to thrive, diarrhea, vomiting, and a characteristic "cabbage-like" odor. Neurological crises can also occur.
Type II Tyrosinemia (HT-2): This form results from a deficiency of the enzyme tyrosine transaminase. It primarily affects the eyes and skin, causing painful corneal lesions (eye pain, redness, and sensitivity to light) and thick, painful skin on the palms and soles (palmoplantar hyperkeratosis). About half of affected individuals may also have intellectual disabilities. Unlike Type I, it does not typically cause liver or kidney disease.
Type III Tyrosinemia (HT-3): This is the rarest type, caused by a defect in the 4-hydroxyphenylpyruvate dioxygenase (HPD) enzyme. Symptoms are highly variable and can include intellectual disabilities, seizures, and a lack of balance and coordination (ataxia). Like Type II, it does not lead to liver or kidney problems.

Can High Tyrosine from Supplements Cause Problems?

While the risks associated with hereditary tyrosinemia are severe, the potential side effects of excessive tyrosine from supplements are generally less severe, but still warrant caution. The body is more capable of handling excess amino acids from dietary sources or moderate supplementation than it is with a complete metabolic block.

However, very high doses of L-tyrosine supplements, especially when taken for extended periods, can lead to adverse effects. Common side effects reported from high doses can include:

Nausea and heartburn
Headaches and fatigue
Nervousness, restlessness, or jitteriness
Joint pain
Elevated blood pressure, especially in those with pre-existing hypertension or those taking certain medications.

Of particular concern are potential drug interactions. L-tyrosine can compete for absorption with L-dopa, a medication for Parkinson's disease, and may interact with MAO inhibitors and thyroid hormones. Therefore, it is crucial to consult a healthcare professional before supplementing, particularly if you have pre-existing medical conditions.

Comparison of High Tyrosine Risks


Feature	Hereditary Tyrosinemia	Excess L-Tyrosine Supplementation
Cause	Genetic metabolic defect preventing normal tyrosine breakdown.	High doses of L-tyrosine supplements, often above recommended levels.
Severity	Severe and potentially fatal, especially Type I.	Generally less severe, with dose-dependent side effects.
Organ Damage	Severe, progressive damage to liver, kidneys, and nervous system, particularly in HT-1.	Typically does not cause permanent organ damage in healthy individuals, though high doses can stress the body.
Symptoms	Wide range of symptoms including failure to thrive, liver/kidney failure, rickets, and neurological issues.	Common side effects are nausea, headaches, fatigue, and potential overstimulation.
Duration	Lifelong condition requiring strict, ongoing management.	Side effects resolve with cessation or reduction of supplementation.
Prevalence	Very rare genetic disease.	Dependent on frequency and dosage of supplement use.

Management of High Tyrosine Levels

For individuals with a diagnosed genetic disorder like tyrosinemia, management is a lifelong process and must be overseen by a medical team. For those experiencing side effects from supplementation, the solution is usually to stop or reduce intake. Here are the primary approaches:

Medication (for Tyrosinemia): For Type I, the drug nitisinone (NTBC) is used to block an enzyme in the tyrosine pathway, preventing the formation of toxic metabolites. This significantly improves prognosis.
Dietary Management: A low-tyrosine diet is critical for all types of tyrosinemia and for supplement users who experience adverse effects. This involves limiting foods high in protein, such as meat, dairy, nuts, and legumes. Specialized medical formulas free of phenylalanine and tyrosine are used to ensure proper nutrition.
Regular Monitoring: Regular blood tests are necessary to monitor tyrosine and phenylalanine levels, especially in patients with tyrosinemia, to guide diet and medication adjustments.
Supplementation Guidance: Anyone considering L-tyrosine supplements, particularly those with existing thyroid or neurological conditions, should consult a doctor first. Adhering to recommended dosages is crucial to avoid potential side effects.

Conclusion

Having too much tyrosine can range from a minor issue resulting from excessive supplement intake to a severe, life-threatening condition caused by a rare genetic disorder. Hereditary tyrosinemia, especially Type I, can cause devastating and progressive damage to the liver and kidneys, while supplement-induced excess is generally milder and resolves upon discontinuation. Regardless of the cause, managing high tyrosine levels requires careful medical attention. Individuals with genetic conditions need strict, lifelong dietary control and medication, while those using supplements should exercise caution and consult a healthcare provider to avoid potential interactions and adverse effects. Early diagnosis and management are key to mitigating the risks associated with excess tyrosine and ensuring a positive health outcome.

For more detailed information on rare metabolic disorders, consult the National Organization for Rare Disorders (NORD).

Frequently Asked Questions

The most dangerous cause of high tyrosine levels is a rare genetic disorder known as tyrosinemia, which prevents the body from properly breaking down the amino acid. This can lead to the buildup of toxic byproducts that damage organs.

Symptoms of Type I tyrosinemia in infants include failure to thrive, a cabbage-like odor, jaundice, diarrhea, and vomiting. If untreated, it can lead to severe liver and kidney failure.

While generally considered safe for short-term use in moderate doses, taking excessive L-tyrosine supplements can cause side effects like nausea, headaches, fatigue, and potential interactions with certain medications.

Treatment depends on the cause. For genetic tyrosinemia, it involves a lifelong low-protein diet and medication (like nitisinone for Type I) to prevent toxic buildup. For supplement-induced excess, stopping or reducing the dose is usually sufficient.

The three types of tyrosinemia differ in their genetic cause and symptoms. Type I is the most severe, affecting the liver and kidneys. Type II primarily causes eye and skin problems. Type III is the rarest, causing neurological issues.

Individuals with hyperthyroidism or Graves' disease should avoid L-tyrosine supplements. Those taking MAO inhibitors or L-dopa for Parkinson's disease should also use caution and consult a healthcare provider.

Transient tyrosinemia is a temporary, non-genetic condition in newborns, often premature infants, where tyrosine levels are elevated due to an immature liver. It usually resolves on its own, sometimes with the help of vitamin C.