Nitisinone 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.

Nitisinone is used to treat a rare genetic condition called hereditary tyrosinemia type 1 (HT-1). 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.

Nitisinone may also be used for purposes not listed in this medication guide.

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).

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

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

Take the nitisinone capsule on an empty stomach, at least 1 hour before or 2 hours after a meal.

You may take nitisinone liquid with or without food.

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.

Shake the oral suspension (liquid) for at least 5 full seconds just before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

If you cannot swallow a capsule whole, open it and sprinkle the medicine into a spoonful of water, baby formula, or applesauce. Swallow the mixture right away without chewing. Do not save it for later use.

If you cannot swallow a tablet whole, crush the tablet and sprinkle the medicine into a spoonful of applesauce. Swallow the mixture right away without chewing. Do not save it for later use.

You may also dissolve a tablet in an oral syringe with water. Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

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

Store tablets at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use.

Store the capsules or liquid in the refrigerator, do not freeze.

After using nitisinone liquid for the first time, you may store the medicine at room temperature for up to 60 days.

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

Tell your doctor if you are pregnant or breastfeeding.

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.

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

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

• chicken, beef, pork, liver, fish, processed meats (bologna, hot dogs, pepperoni, hard sausages), meat tenderizer, herring or other dried fish;

• cheese, milk, sour cream, yogurt;

• beer, wine, distilled liquor;

• avocados, bananas, carrots, potatoes, spinach, tomatoes, raisins, red plums,

• oatmeal, brown rice,

• soy sauce, soy protein, tofu, bean curd, garbanzo beans, soy beans, and certain nuts or seeds; or

• foods that contain an artificial sweetener--diet soda, some foods labeled as "sugar-free" or "zero calorie."

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.

Get emergency medical help if you have signs of an allergic reaction: 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.

Nitisinone may cause serious side effects. Call your doctor at once if you have:

• a sudden change in behavior, ability, or development (sitting up, crawling, walking, talking, etc);

• easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

• nausea, diarrhea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• vision problems;

• eye pain, redness or swelling, burning, white or yellow patches on your eyes; or

• calluses, peeling, or hardened skin on the palms of your hands or the soles of your feet.

Common side effects of nitisinone may include:

• vision changes, your eyes may be more sensitive to light;

• eye pain, red or puffy eyes;

• nosebleeds;

• increased sensitivity of your eyes to light;

• rash or itching;

• dry or peeling skin; or

• thinning hair.

The liquid form of nitisinone may contain glycerol and can cause headache, upset stomach, or diarrhea.

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.

Other drugs may affect 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.