SIDE EFFECTS: Injection site reactions (pain/swelling/redness), diarrhea, upset stomach, nausea, or vomiting may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Flu-like symptoms such as headache, tiredness, fever, chills, and muscle aches may occur, especially when you first start this medication. These symptoms usually last about 1 day after the injection and improve or go away after a few months of continued use. You can reduce these side effects by injecting this medicine at bedtime and using a fever reducer/pain reliever such as acetaminophen before or after each dose. Consult your doctor or pharmacist for more information. 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: lightheadedness, fainting, mental/mood changes (e.g., confusion, depression), shaking (tremors), trouble walking, slow/fast/irregular heartbeat, shortness of breath, swelling of the ankles/feet, increasing tiredness, joint pain, butterfly-shaped rash on the face, easy bleeding/bruising, persistent nausea/vomiting, signs of infection (e.g., fever, persistent sore throat), stomach/abdominal pain, black/tarry stools, dark urine, signs of kidney problems (such as change in the amount of urine), yellowing eyes/skin. Get medical help right away if any of these rare but very serious side effects occur: chest/jaw/left arm pain, weakness on one side of the body, slurred speech, sudden vision changes, seizures, pain/redness/swelling of the arms/legs, calf pain/swelling that is warm to the touch, coughing up blood. 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 using interferon, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients (such as dry natural rubber/latex found in the packaging), 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: heart disease (e.g., angina, irregular heartbeat, congestive heart failure), liver disease, seizure disorder, blood cell disorders (e.g., anemia, neutropenia, thrombocytopenia). This drug may make you tired or cause mental changes. Alcohol or marijuana can make you more tired or cause mental changes. 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. Do not have immunizations/vaccinations without the consent of your doctor. Children, especially those younger than 1 year, may be at greater risk for effects on the liver while using this drug. The manufacturer recommends regular laboratory tests (liver function tests), especially in children younger than 1 year. This medication is not recommended for use during pregnancy. Consult your doctor for more details. It is not known whether this drug passes into breast milk. 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. Some products that may interact with this drug include: drugs that may affect your immune system (e.g., cancer chemotherapy, prednisone, cyclosporine), hydroxyurea, theophyllines (e.g., aminophylline, theophylline).

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.