Avonex Pen

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

Most people have flu-like symptoms such as headache, tiredness, fever, chills, and muscle aches when they 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 lessen these side effects by injecting this medicine at bedtime and by using fever reducers/pain relievers such as acetaminophen or ibuprofen before each dose. Ask 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 new or worsening depression, thoughts of suicide, psychosis), feeling too hot or cold (more than others around you), blue fingers/toes, easy bleeding/bruising, pus or change in skin color at the injection site, joint pain/swelling, signs of kidney problems (such as a change in the amount of urine), signs of liver problems (such as nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine), new or worsening symptoms of heart failure (such as shortness of breath, swelling ankles/feet, unusual tiredness, unusual/sudden weight gain).

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

This medication may lower your ability to fight infections. This may make you more likely to get a serious (rarely fatal) infection or make any infection you have worse. Tell your doctor right away if you have any signs of infections (such as sore throat that doesn't go away, fever, chills, cough).

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 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 natural rubber/latex), 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: bleeding/blood problems, heart problems (such as heart failure, angina, fast/irregular heartbeat), liver disease, mental/mood disorders (such as depression, psychosis, suicidal thoughts), seizure disorder, thyroid disease.

Interferon can make you more likely to get infections or may make current infections worse. Stay away from anyone who has an infection that may easily spread (such as chickenpox, COVID-19, measles, flu). Talk to your doctor if you have been exposed to an infection or for more details.

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

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 in small amounts, but is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.

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 their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

Do not share this medication with others.

Lab and/or medical tests (such as complete blood count, liver/thyroid function) should be done while you are using this medication. Keep all medical and lab appointments.

If you miss a dose, use it as soon as you remember. Do not use this medication 2 days in a row. Do not double the dose to catch up. Follow your usual schedule the next week.

Store in the refrigerator away from light. Do not freeze. This medication may also be stored at room temperature for up to 7 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.