See also Warning section.

Before using interferon alfa, 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 albumin), 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: blood cell disorders (such as anemia, neutropenia, thrombocytopenia), blood clots, cancer, diabetes, eye problems, heart disease (such as angina, irregular heartbeat), high blood pressure, HIV infection, immune system diseases (such as lupus, psoriasis, rheumatoid arthritis), intestinal disease (such as colitis), kidney disease, liver disease (such as autoimmune hepatitis, decompensated liver disease), lung diseases (such as chronic obstructive pulmonary disease-COPD, asthma, pneumonia), mental/mood disorders (such as anxiety, depression), high blood triglyceride levels, pancreatitis, seizure disorder, thyroid disease, use/abuse of drugs/alcohol.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. 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 (cannabis).

Tell your health care professional that you are using interferon alfa before having any immunizations/vaccinations. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).

To lower your risk of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Children may be more sensitive to the side effects of this drug, especially mental/mood changes (such as severe depression, thoughts/attempts of suicide). Interferon and ribavirin may also slow down a child's rate of growth. Normal weight gain and rate of growth usually return after treatment is completed but the final adult height may be lower than expected. Monitor your child's height and weight periodically during treatment.

Older adults may be more sensitive to the effects of the drug, especially dizziness, mental/mood changes, and effects on the heart.

During pregnancy, interferon alfa should be used only when clearly needed. Discuss the risks and benefits with your doctor.

Interferon alfa, when used in combination with ribavirin, must not be used during pregnancy by either the pregnant woman or her male partner. The combination may cause harm to an unborn baby. Reliable forms of birth control must be used whenever at least one sexual partner is using these medicines together. Female patients should keep using birth control for 9 months after stopping treatment. Male patients should keep using birth control for 6 months after stopping treatment. If you or your partner become pregnant, or if you think you or your partner may be pregnant, tell your doctor right away.

It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.