Istradefylline is used along with the combination of levodopa and carbidopa (Duopa, Rytary, Sinemet, others) to treat “off” episodes (times of difficulty moving, walking, and speaking that may happen as medication wears off or at random) in people with Parkinson’s disease (PD; a disorder of the nervous system that causes difficulties with movement, muscle control, and balance). Istradefylline is in a class of medications called adenosine receptor antagonists. It works by changing the activity of certain natural substances in the brain.

Side Effects Of Istradefylline

Istradefylline may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • dizziness
  • constipation
  • loss of appetite
  • difficulty falling asleep or staying asleep

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical treatment:

  • worsening or more frequent body movements that you cannot control
  • hallucinations (seeing things or hearing voices that do not exist)
  • being overly suspicious or feeling people want to harm you
  • believing things that are not real
  • aggressive behavior, agitation, or confusion

Istradefylline may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Warnings & Precautions

Before taking istradefylline:

  • tell your doctor and pharmacist if you are allergic to istradefylline, any other medications, or any of the ingredients in istradefylline tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: clarithromycin (Biaxin, in Prevpac); certain antifungals such as itraconazole (Onmel, Sporanox) or ketoconazole; digoxin (Lanoxin), enzalutamide (Xtandi); certain medications for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) such as efavirenz (Sustiva, in Atripla), indinavir (Crixivan), nelfinavir (Viracept), nevirapine (Viramune), ritonavir (Norvir, in Kaletra), and saquinavir (Invirase); modafinil (Provigil); nefazodone; pioglitazone (Actos, in Duetact, Oseni); rifabutin (Mycobutin); rifampin (Rifadin); certain medications for seizures such as carbamazepine (Equetro, Tegretol, Teril), oxcarbazepine (Trileptal), phenobarbital, and phenytoin (Dilantin, Phenytek); oral steroids such as dexamethasone, methylprednisolone (Medrol), and prednisone; or telithromycin (Ketek). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with istradefylline, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • tell your doctor and pharmacist what herbal products you are taking, especially St. John’s wort. You should not take St. John’s wort during your treatment with istradefylline.
  • tell your doctor if you have or have ever had a psychotic disorder (a condition that causes difficulty telling the difference between things or ideas that are real and things or ideas that are not real), body movements that you cannot control, or liver disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. You should not become pregnant while you are taking istradefylline. You should use effective birth control to prevent pregnancy during your treatment with istradefylline. If you become pregnant while taking istradefylline, call your doctor.
  • tell your doctor if you use tobacco products (cigarettes, cigars, pipe tobacco, or hookah [waterpipe] tobacco). Smoking tobacco products may decrease the effectiveness of this medication.
  • you should know that some people who took medications such as istradefylline developed gambling problems or other intense urges or behaviors that were compulsive or unusual for them, such as increased sexual urges or behaviors, uncontrolled spending, or binge or compulsive eating. Call your doctor if you have an urge to gamble that is difficult to control, you have intense urges, or you are unable to control your behavior. Tell your family members about this risk so that they can call the doctor even if you do not realize that your gambling or any other intense urges or unusual behaviors have become a problem.

Istradefylline Dosage

Istradefylline comes as a tablet to take by mouth. It is usually taken with or without food once daily. Take istradefylline at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take istradefylline exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.


Keep all appointments with your doctor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.