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Generic name: istradefylline [ IS-tra-DEF-i-lin ]
Brand name: Nourianz
Dosage form: oral tablet (20 mg; 40 mg)
Drug class: Miscellaneous antiparkinson agents

Medically reviewed by on Sep 25, 2023. Written by Cerner Multum.

What is istradefylline?

Istradefylline is given with levodopa and carbidopa to treat "wearing-off" episodes (muscle stiffness, loss of muscle control) in people with Parkinson's disease.

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

Istradefylline 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.

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

You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking istradefylline. Talk with your doctor if this occurs.

Common side effects of istradefylline 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

Tell your doctor if you have ever had:

Tell your doctor if you are pregnant or breastfeeding.

How should I take istradefylline?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Istradefylline is usually taken once per day. Follow your doctor's dosing instructions very carefully.

You may take istradefylline with or without food.

Store at room temperature away from moisture and heat.

Istradefylline dosing information

Usual Adult Dose for Parkinson's Disease:

Initial dose: 20 mg orally once a day
-Dose may be increased based on individual need and tolerability
Maintenance dose: 20 to 40 mg orally once a day
Maximum dose: 40 mg/day

Use: As adjunctive treatment to levodopa/carbidopa in patients with Parkinson's disease experiencing OFF episodes.

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 istradefylline?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

What other drugs will affect istradefylline?

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Other drugs may affect istradefylline, 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.