Diarrhea is a common side effect. Tell your doctor promptly if you have diarrhea. Ask your healthcare provider about how to manage diarrhea, such as by changing your diet, taking anti-diarrhea medicine, and drinking enough water to prevent dehydration.
Nausea, upset stomach, abdominal pain, dizziness, or tiredness may also occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.
This medication may cause or worsen high blood pressure. Your blood pressure should be checked regularly. Your doctor may start or adjust medication(s) to treat high blood pressure.
Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor right away if you have any serious side effects, including: bruising/bleeding.
Fostamatinib may rarely cause serious (possibly fatal) liver disease. Get medical help right away if you have any symptoms of liver damage, such as: nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine.
This medication may lower your ability to fight infections. This may make you more likely to get a serious (rarely fatal) infection or make any infection you have worse. Tell your doctor right away if you have any signs of infection (such as sore throat that doesn't go away, fever, chills, cough).
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at MedWatch: The FDA Safety Information and Adverse Event Reporting Program.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.