See also Warning section.
Nausea, headache, back pain, or stomach/abdominal pain may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.
People using this medication may have serious side effects. However, your doctor has prescribed this drug because he or she has judged that the benefit to you is greater than the risk of side effects. Careful monitoring by your doctor may decrease your risk.
Tell your doctor right away if you have any serious side effects, including: signs of liver problems (such as nausea/vomiting that doesn't stop, loss of appetite, severe stomach/abdominal pain, yellowing eyes/skin, dark urine).
This medication decreases bone marrow function, an effect that may lead to a low number of blood cells such as red cells, white cells, and platelets. This effect can cause anemia, decrease your body's ability to fight an infection, or cause easy bruising/bleeding. Tell your doctor right away if you develop any of the following symptoms: unusual tiredness, pale skin, signs of infection (such as sore throat that doesn't go away, fever, chills, painful rash/sores, frequent/painful urination), easy bruising/bleeding.
This medication may increase your risk of getting a rare but very serious (possibly fatal) brain infection (progressive multifocal leukoencephalopathy-PML). Get medical help right away if you have any of these side effects: clumsiness, loss of coordination/balance, weakness, sudden change in your thinking (such as confusion, difficulty concentrating, memory loss), difficulty talking/walking, seizure, vision changes.
Get medical help right away if you have any very serious side effects, including: shortness of breath, fast/irregular heartbeat, swelling of the ankles/feet.
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.