Skip to main content


Generic name: fostamatinib [ FOS-ta-MA-ti-nib ]
Brand name: Tavalisse
Dosage form: oral tablet (100 mg; 150 mg)
Drug class: Miscellaneous coagulation modifiers

Medically reviewed by on Oct 12, 2022. Written by Cerner Multum.

What is fostamatinib?

Fostamatinib is used to treat chronic immune thrombocytopenia, a bleeding condition caused by a lack of platelets in the blood. fostamatinib is given after other treatments have failed.

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


Fostamatinib can raise your blood pressure, sometimes to dangerous levels. Fostamatinib may also cause liver problems, severe diarrhea, and infections.

Call your doctor if you have: headaches, chest pain, shortness of breath, severe diarrhea, stomach pain, fever, or sore throat.

Before taking this medicine

Fostamatinib is not approved for use by anyone younger than 18 years old.

Tell your doctor if you have ever had:

Do not use fostamatinib if you are pregnant. It could harm the unborn baby. Use effective birth control to prevent pregnancy while you are using fostamatinib and for at least 1 month after your last dose.

Do not breast-feed while using this medicine, and for at least 1 month after your last dose.

How should I take fostamatinib?

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.

You may take fostamatinib with or without food.

Fostamatinib can cause diarrhea. You may need to change your diet, drink extra fluids, or take anti-diarrhea medication. Follow your doctor's instructions for treating or preventing diarrhea.

Fostamatinib can raise your blood pressure, sometimes to dangerous levels. Your blood pressure will need to be checked often.

You will also need frequent medical tests. Your doctor may change your dose, or you may need to stop using fostamatinib based on test results.

Store at room temperature away from moisture and heat. Keep the tablets in their original container, along with the packet or canister of moisture-absorbing preservative.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time. Do not use 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 fostamatinib?

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

Fostamatinib 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.

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

  • severe diarrhea;

  • stomach pain (upper right side);

  • dark urine, jaundice (yellowing of the skin or eyes);

  • headaches, chest pain, shortness of breath; or

  • fever, sore throat, or other signs of infection.

Your fostamatinib doses may be delayed or permanently discontinued if you have certain side effects.

Common side effects of fostamatinib 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.

Fostamatinib dosing information

Usual Adult Dose for Thrombocytopenia:

100 mg orally 2 times a day; after a month, if platelet count has not increased to at least 50 x 10(9)/L, increase to 150 mg orally 2 times a day

-This drug may be taken with or without food.
-In the case of a missed dose, instruct patients to take their next dose at its regularly scheduled time.
-Use the lowest dose to achieve and maintain a platelet count at least 50 x 10(9)/L to reduce the risk of bleeding.

Use: For the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment

What other drugs will affect fostamatinib?

Other drugs may affect fostamatinib, 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.