Before taking this medication, tell your doctor if you have
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heart disease,
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kidney disease, or
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liver disease.
You may not be able to take metyrosine, or you may require a lower dose or special monitoring during treatment if you have any of the conditions listed above.
The safety of metyrosine for use by pregnant or nursing women has not been established. Do not take metyrosine without first talking to your doctor if you are pregnant or are breast-feeding a baby.
Take metyrosine exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
Take each dose with a full glass of water.
Drink plenty of fluid every day—at least six to eight full glasses (8 ounces)—to prevent metyrosine crystals from forming in your urine.
Store metyrosine at room temperature away from moisture and heat.
Take the missed dose as soon as you remember. However, if it is almost time for
your next dose, skip the missed dose and take only your next regularly scheduled dose.
If you experience any of the following serious side effects, stop taking metyrosine and seek emergency medical attention:
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an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);
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drooling;
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difficulty speaking;
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tremors;
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muscle spasms;
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disorientation;
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diarrhea; or
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painful urination.
Other, less serious side effects may be more likely to occur. Continue to take metyrosine and talk to your doctor if you experience
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depression, hallucinations, disorientation, and confusion;
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stomach upset, vomiting, or abdominal pain; or
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decreased salivation and a dry mouth.
Sedation is a common side effect. It is usually most bothersome at the start of therapy and will decrease after the first week of treatment. Likewise, insomnia and stimulation often occur for a few days after therapy is discontinued.
You may experience headaches.
Metyrosine crystals may form in your urine. It is very important to maintain proper fluid intake, at least 6 to 8 (8 ounce) glasses of water or another fluid daily, to prevent crystals from forming.
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.
Use caution when driving, operating machinery, or performing other hazardous activities. Metyrosine may cause drowsiness. If you experience drowsiness, avoid these activities.
Use alcohol cautiously. Alcohol may increase drowsiness while you are taking metyrosine.
Contact your doctor if you experience drooling, difficulty speaking, tremors, disorientation, diarrhea, or painful urination.
Drink plenty of fluid every day—at least six to eight full glasses (8 ounces)—to prevent metyrosine crystals from forming in your urine.
Use caution when driving, operating machinery, or performing other hazardous activities. Metyrosine may cause drowsiness. If you experience drowsiness, avoid these activities.
Use alcohol cautiously. Alcohol may increase drowsiness while you are taking metyrosine.
Some medicines use to treat psychiatric conditions may cause increased side effects if they are taken during therapy with metyrosine. Drooling, tremor, muscle spasms, and speech difficulty may be more likely to occur if you are taking metyrosine with drugs such as
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haloperidol (Haldol) and
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phenothiazines, including chlorpromazine (Thorazine), fluphenazine (Prolixin), mesoridazine (Serentil), thioridazine (Mellaril), trifluoperazine (Stelazine), and perphenazine (Trilafon).
Drugs other than those listed here may also interact with metyrosine or affect your condition. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines.
Seek emergency medical attention.
Symptoms of a metyrosine overdose include sedation, anxiety, tremor, tightening of the jaw, diarrhea, and dry mouth.