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Generic name: nitisinonenye-TIS-i-none ]
Drug class: Miscellaneous metabolic agents

Medically reviewed by Last updated on Mar 30, 2023.

What is Nityr?

Nityr is a hydroxyphenyl-pyruvate dioxygenase inhibitor.

Nityr is used to treat adult and children with a rare genetic condition called hereditary tyrosinemia type 1 (HT-1) along with with dietary restriction of tyrosine and phenylalanine. HT-1 is a metabolic disorder that occurs when the body does not produce enough of an enzyme that breaks down proteins from certain foods. This condition occurs most often in young babies.

Nityr works by preventing the body from breaking down an amino acid called tyrosine and by keeping other toxic substances from building up and causing harm to your liver or kidneys.


Call your doctor at once if you have vision problems, eye pain, eye redness or burning, easy bruising, unusual bleeding, itching, or jaundice (yellowing of the skin or eyes). Tell your doctor if your baby has a sudden change in behavior, ability, or development (sitting up, crawling, walking, talking, etc).

Before taking this medicine

Tell your doctor if you have any medical conditions affecting your eyes.

Tell your doctor if you are pregnant or breastfeeding.

How should I take Nityr?

Take Nityr exactly as directed. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Do not change your medication dose or schedule without your doctor's advice.

You must avoid certain foods for your treatment to be effective. Follow the diet plan created for you by your doctor or nutrition counselor.

High protein foods are high in tyrosine and phenylalanine (including artificial sweeteners such as aspartame, Equal, or Nutrasweet). Since babies and children need protein to grow and develop, special foods have been developed to replace the high protein foods.

You may take Nityr tablets with or without food.

People who have a problem swallowing Nityr tablets whole, including children, can take Nityr tablets mixed with water in an oral syringe or crushed and mixed with applesauce. Nityr tablets should not be mixed in any other liquid or food.

Take Nityr within 24 hours of adding water to tablets in an oral syringe. Throw away any unused tablet and water mixture stored in the oral syringe after 24 hours of being mixed together.

Take Nityr within 2 hours of adding crushed Nityr tablets to applesauce. Throw away any crushed tablet and applesauce mixture that has not been used within 2 hours.

Keep Nityr tablets and Nityr that has been prepared in an oral syringe with water or in applesauce out of direct sunlight.

You may need frequent blood tests. Your vision may also need to be checked.

Store Nityr tablets at room temperature between 20°C to 25°C (68°F to 77°F), with excursions permitted between 15°C and 30°C (59°F and 86°F). Keep the tablets in the container they were dispensed in and keep the container tightly closed.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Nityr?

While you are taking Nityr, you must not eat foods that are high in tyrosine or phenylalanine, including:

There are other foods that may contain tyrosine or phenylalanine. Get familiar with the list of foods you must avoid to help control your condition.

Nityr side effects

Get emergency medical help if you have signs of an allergic reaction to Nityr: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may result from not properly following your diet plan and consuming restricted foods or beverages.

Call your doctor at once if you have:

Common Nityr side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Nityr?

Other drugs may interact with nitisinone, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Nityr only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.