SIDE EFFECTS: 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 your doctor has prescribed this medication because he or she 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 www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking fostamatinib, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: high blood pressure, liver problems, surgery to remove spleen, bleeding/blood problems (such as blood clots). This drug may make you dizzy. Alcohol or marijuana can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana. Fostamatinib can make you more likely to get infections or may worsen any current infections. Avoid contact with people who have infections that may spread to others (such as chickenpox, measles, flu). Consult your doctor if you have been exposed to an infection or for more details. Do not have immunizations/vaccinations without the consent of your doctor. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose). Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). Older adults may be more sensitive to the side effects of this drug, especially high blood pressure. Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using fostamatinib. Fostamatinib may harm an unborn baby. Ask about reliable forms of birth control while using this medication and for at least 1 month after stopping treatment. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication. It is unknown if this medication passes into breast milk. Because of the possible risk to the infant, breast-feeding while using this drug and for at least 1 month after stopping treatment is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Other medications can affect the removal of fostamatinib from your body, which may affect how fostamatinib works. Examples include azole antifungals (such as ketoconazole/itraconazole), rifamycins (such as rifampin/rifampicin), St. John's wort, drugs used to treat seizures (such as carbamazepine, phenytoin), among others. Fostamatinib can slow down the removal of other drugs from your body, which may affect how they work. Examples of affected drugs include some statin drugs (such as rosuvastatin), among others.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.