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General Information

Tyrosine is an amino acid that is used by the body to make proteins. It is a building block for thyroid hormones, melanin, and neurotransmitters (chemical messengers) in the brain. Tyrosine can be made in the body from phenylalanine, another amino acid, or it can be obtained through dietary proteins in dairy products, meats, fish, eggs, nuts, beans, oats, and wheat.

Common Name(s)

L-tyrosine, tyrosine

Scientific Name(s)


How is this product usually used?

L-tyrosine is usually taken by mouth. It is available in different forms, including capsules, tablets, liquids, and powders.

As a supplement, L-tyrosine is normally taken as 10 g once or twice a day, up to one hour before or during periods of physical stress.

Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.

What is this product used for?

L-tyrosine supplements are used to help decrease cognitivecognitiverelating to the ability to think, reason, remember, and discern fatigue due to physically stressful situations (e.g., extended wakefulness, exposure to cold, excessive noise).

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

What else should I be aware of?

L-tyrosine is naturally found in many foods, so it is generally safe when taken in the amounts commonly found in foods.

Taking L-tyrosine as a supplement may improve alertness and cognitivecognitiverelating to the ability to think, reason, remember, and discern function in physically stressful situations such as sleep deprivation and cold temperatures. Taking L-tyrosine may also improve working memory in a multitasking environment.

L-tyrosine is generally safe and well tolerated, but should only be used on a short-term, occasional basis. Side effects that have been reported include nausea, fatigue, headache, and heartburn.

L-tyrosine may reduce the effectiveness of levodopa, a medication used by people with Parkinson's disease, by decreasing its absorption. Therefore, these 2 medications should be taken at least 2 hours apart.

If you take thyroid hormone medications and have hyperthyroidism or Graves' disease, talk to your doctor before taking L-tyrosine. L-tyrosine is a precursor to thyroxine, a type of thyroid hormone, and may increase thyroid hormone levels.

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.


  • Health Canada. Licensed Natural Health Products database. Tyrosine, L-., Accessed August 30, 2011.
  • L-Tyrosine (monograph). Natural Medicines Comprehensive Database. (Accessed online August 30, 2011).

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