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Generic name: metyrosineme-TYE-roe-seen ]
Drug class: Miscellaneous cardiovascular agents

Medically reviewed by on Jan 20, 2023. Written by Cerner Multum.

What is Demser?

Demser is used to treat pheochromocytoma (tumor of the adrenal gland).

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

Demser side effects

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

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

  • drooling, trouble speaking;

  • confusion, hallucinations;

  • tremors or muscle spasms;

  • painful or difficult urination;

  • urine that looks cloudy; or

  • severe or ongoing diarrhea.

Common side effects of Demser 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.


Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use Demser if you are allergic to it.

Demser is not approved for use by anyone younger than 12 years old.

Tell your doctor if you have ever had:

Tell your doctor if you are pregnant or breast-feeding.

How should I take Demser?

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.

Drink 6 to 8 full glasses of water each day to help keep crystals from forming in your urine.

Demser can affect the results of certain medical tests. Tell any doctor who treats you that you are using this medicine.

Store at room temperature away from moisture and heat.

For 2 or 3 days after you stop taking Demser, you may have withdrawal symptoms such as trouble sleeping or increased alertness.

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.

Overdose symptoms may include anxiety, depression, agitation, dry mouth, diarrhea, tremors or shaking, or tightness in your jaw.

What should I avoid while taking Demser?

Avoid driving or hazardous activity until you know how Demser will affect you. Your reactions could be impaired.

Drinking alcohol with this medicine can cause side effects.

What other drugs will affect Demser?

Using Demser with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all other medications you use, especially antipsychotic medicine.

Other drugs may affect Demser, 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 this medication only for the indication prescribed.

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