It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.
This medicine may cause some people to be anxious, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you or your caregiver notice any of these side effects, tell your doctor right away.
Check with your doctor right away if you have dark urine, persistent loss of appetite, flu-like symptoms, headache, continuing vomiting, general feeling of tiredness or weakness, light-colored stools, right upper stomach pain or tenderness, or yellow eyes or skin. These could be symptoms of a serious liver problem.
Avoid alcohol while you are taking this medicine. It can cause serious liver problems.
This medicine may cause serious allergic reactions including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash; itching; hoarseness; trouble breathing; trouble swallowing; or any swelling of your hands, face, or mouth while you are using this medicine.
This medicine may lower the number of white blood cells in the blood. This will increase your chance of getting an infection. It can also lower the number of platelets in the blood. Platelets are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:
- If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
- Check with your doctor immediately if you notice any unusual bleeding or bruising; black, tarry stools; blood in the urine or stools; or pinpoint red spots on your skin.
- Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
- Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
- Be careful not to cut yourself when you are using sharp objects, such as a safety razor or fingernail or toenail cutters.
- Avoid contact sports or other situations where bruising or injury could occur.
This medicine may cause redness, pain, or swelling at the injection site. Some patients have developed skin infections or a permanent depression (necrosis) under the skin at the injection site. Contact your doctor right away if you notice any of these side effects at the injection site: depressed or indented skin; blue-green to black skin discoloration; or pain, redness, or sloughing (peeling) of the skin.
This medicine commonly causes a flu-like reaction, with aching muscles, chills, fever, headache, joint pain, and nausea. Using your shot at bedtime may allow you to sleep through the symptoms. Your doctor may want you to take a medicine for pain and fever (e.g., acetaminophen or ibuprofen) to help control these effects. Follow your doctor's instructions carefully about how to prevent or treat these symptoms.
This medicine contains albumin, which comes from human blood. Some human blood products have transmitted certain viruses to people who have received them. The risk of getting a virus from medicines made of human blood has been greatly reduced in recent years. This is the result of required testing of human donors for certain viruses, and testing during manufacture of these medicines. Although the risk is low, talk with your doctor if you have concerns. The Avonex® prefilled autoinjector pen and prefilled syringe does not contain albumin which comes from donated human blood.