This medication is used to treat multiple sclerosis (MS). Peginterferon is not a cure for MS, but it may help to decrease the number of episodes of disease worsening (relapses) and slow the worsening of the disease.

Read the Medication Guide and Instructions for Use provided by your pharmacist before you start using peginterferon and each time you get a refill. Ask your health care professional how to prepare and use this medication. If you have any questions, ask your doctor or pharmacist.

Inject this medication under the skin as directed by your doctor, usually every 14 days. The injection is given in the thigh, abdomen, or the back of the upper arm. Check the injection site 2 hours after injecting to see if there is any reaction at the injection site. Tell the doctor of any skin reactions that do not go away after a few days.

To reduce your risk of side effects, your doctor may direct you to start this medication at a low dose and gradually increase your dose. A starter pack with different doses of this medication may be used when starting this medication. Follow your doctor's instructions carefully.

Take the medication out of the refrigerator at least 30 minutes before you inject it to allow it to reach room temperature. Do not warm up this medication any other way (for example, place it in hot water). Before using, check this product for particles or discoloration. If either is present, do not use the liquid. Before injecting each dose, clean the skin you are going to inject into (the injection site) with rubbing alcohol. Change the injection site each time to lessen injury under the skin. Do not inject into skin that is irritated, bruised, scarred, or infected. To lessen bruising, do not rub the injection site after a shot. Learn how to store and discard medical supplies safely.

Use this medication regularly to get the most benefit from it. To help you remember, use it at the same time and same day of the week.

You may need to take other medications to reduce common side effects such as fever and pain (such as acetaminophen, ibuprofen). Consult your doctor or pharmacist about how to use these medications safely with peginterferon.

Tell your doctor if your condition gets worse.

Pain, redness, itching, or swelling at the injection site may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Flu-like symptoms (such as headache, fever, chills, weakness, nausea/vomiting, muscle aches/pain) may also occur, especially when you first start this medication. You can reduce these side effects by using fever reducers/pain relievers such as acetaminophen or ibuprofen. Consult your doctor or pharmacist for more information.

Remember that this medication has been prescribed because your doctor 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:

• mental/mood changes (such as depression, rare thoughts of suicide)
• symptoms of liver disease (such as nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine)
• pus or change in skin color (blue-black) at the injection site
• signs of infection (such as sore throat that doesn't go away, fever)
• easy bruising/bleeding
• fast/slow/irregular heartbeat
• new or worsening symptoms of heart failure (such as shortness of breath, swelling ankles/feet, unusual tiredness, unusual/sudden weight gain)
• intolerance to cold or heat
• signs of kidney problems (such as a change in the amount of urine)

Get medical help right away if you have any very serious side effects, including:

• seizures
• chest pain

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.

Before using peginterferon, tell your doctor or pharmacist if you are allergic to it; or to interferon; or if you have any other allergies. This product may contain inactive ingredients, 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 disorders (such as anemia, low platelets, low white blood cells)
• bleeding problems
• heart disease (such as heart failure, angina, fast/irregular heartbeat)
• liver disease
• kidney disease
• mental/mood disorders (such as depression, psychosis, suicidal thoughts)
• seizures
• thyroid disease

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

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

This medication passes into breast milk, but is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.

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.

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 1-800-222-1222. Canada residents can call 1-844-764-7669.

Do not share this medication with others.

Lab and/or medical tests (such as liver function, complete blood count) may be done while you are using this medication. Keep all medical and lab appointments. Consult your doctor for more details.

It is important to use each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule. Do not double the dose to catch up.

Store in the refrigerator. Do not freeze. Do not use the medication if it has been frozen. Keep the medication in the original carton to protect from light. This medication may be taken out of the refrigerator and put back in the refrigerator if needed. The total time out of the refrigerator should not be more than 30 days. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.