Ropeginterferon alfa-2b is used in adults to treat polycythemia vera, which is a disorder that affects your body's ability to produce blood cells.

Ropeginterferon alfa-2b may also be used for purposes not listed in this medication guide.

You should not use ropeginterferon alfa-2b if you are allergic to it, or if you:

• have liver disease;
• have or had severe mental health problems, especially severe depression, thoughts of suicide;
• have or had a serious autoimmune disease; or
• have received a transplant and take medications that weaken the immune system.

Tell your doctor if you:

• are being treated for a mental illness or had treatment in the past for any mental illness;
• have diabetes;
• have or ever had any heart problems or high blood pressure;
• have or ever had bleeding problems or a blood clot;
• have or ever had low blood cells;
• have a condition that suppresses your immune system;
• have hepatitis B or HIV; or
• kidney or liver problems.

You may need to have a negative pregnancy test before starting this treatment.

May harm an unborn baby. Do not use if you are pregnant. Use effective birth control while using ropeginterferon alfa-2b and for at least 8 weeks after your last dose. This medicine may affect your menstrual cycle. Tell your doctor if you become pregnant.

Do not breastfeed while using this medicine, and for at least 8 weeks after your last dose.

Use Ropeginterferon Alfa-2B (Subcutaneous) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives, or a rash that spreads and causes blistering and peeling; chest pain, anxiety, difficult breathing, feeling light-headed; swelling of your face, lips, tongue, or throat.

Tell your doctor right away if you have unusual changes in mood or behavior, such as: depression, irritability, feeling hostile or aggressive, hallucinations, or thoughts about hurting yourself.

Call your doctor at once if you have:

• pain and burning when you urinate, increased urination;
• new or worsening cough, cough with mucus, trouble breathing;
• vision changes;
• liver problems--diarrhea, loss of appetite, pain or swelling in your stomach, swelling in your legs, easy bleeding, drowsiness, confusion, or jaundice (yellowing of the skin or eyes);
• kidney problems--swelling, urinating less, feeling tired or short of breath; or
• low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.

Common side effects may include:

• flu-like symptoms (tiredness, weakness, fever, chills, muscle aches, and joint pain);
• itching; or
• sore throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Avoid driving or hazardous activity until you know how this medicine will affect you. Dizziness or drowsiness can cause falls, accidents, or severe injuries.