Your doctor will want to check your progress at 3 months and 6 months after the first injection, then every 6 months after that. Blood tests may be needed to check for unwanted effects.
Tell your doctor if you are currently taking interferon beta (Avonex®, Betaseron®, or Rebif®), azathioprine (Imuran®), 6-mercaptopurine (Purinethol®), cyclosporine (Gengraf®, Neoral®, or Sandimmune®), or methotrexate Rheumatrex® or Trexall®). Natalizumab should not be given together with these medicines.
This medicine may increase your risk of developing infections, including a rare and serious brain infection called progressive multifocal leukoencephalopathy (PML). Stop using this medicine and check with your doctor right away if you are having more than one of these symptoms: back pain, blurred vision, confusion, convulsions, difficulty with walking or other movements, dizziness, drowsiness, fever, headache, problems with vision or speaking, or unusual tiredness or weakness.
Natalizumab may cause a rare condition called immune reconstitution inflammatory syndrome (IRIS). This may occur after a person who gets PML stops using the medicine. Tell your doctor right away if you have an inflammatory reaction to an infection that includes mild burning, stinging, or tingling of the skin, or a feeling of heat, redness, or swelling of the skin.
Liver problems may occur while you are using this medicine. Stop using this medicine and check with your doctor right away if you are having more than one of these symptoms: abdominal pain or tenderness, clay-colored stools, dark urine, decreased appetite, fever, headache, itching, loss of appetite, nausea and vomiting, skin rash, swelling of the feet or lower legs, unusual tiredness or weakness, or yellow eyes or skin.
This medicine may cause a serious type of allergic reaction called anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Tell your doctor right away if you have a rash; hives; itching; swelling of the face, tongue, and throat; trouble breathing; or chest pain after you receive the injection.