Headache, nausea, diarrhea, or cold/flu symptoms (such as runny nose, congestion) may occur. Pain, irritation, or swelling at/near the injection site may also occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
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: shortness of breath, change in the amount of urine.
Because abatacept works by weakening the immune system, it 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 immediately if you have any signs of infection (such as cough, sore throat, fever, chills, pain when urinating).
The immune system is also important in preventing and controlling cancer. Very rarely, people using abatacept have developed cancer (such as lymphoma, lung cancer). Tell your doctor immediately if you develop symptoms such as unusual lumps/growths, swollen glands, night sweats, unexplained weight loss, shortness of breath, wheezing, persistent 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.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.