Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Betaseron (Interferon-beta-1b). If you are concerned about side effects, discuss the risks and benefits of Betaseron (Interferon-beta-1b) with your doctor.

The following side effects have been reported by at least 1% of people taking Betaseron (Interferon-beta-1b). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• flu-like symptoms (e.g., Fever, chills, sweating, muscle aches, tiredness)
• injection site reactions (e.g., skin irritation, swelling, pain, bruising, itching, bleeding)

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• decreased coordination
• signs of Anemia (low red blood cells; e.g., dizziness,  pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood,  bleeding gums, cuts that don't stop bleeding)
• signs of depression (feeling sad, losing interest in things you used to enjoy, weight changes, changes in sleep habits, feelings of guilt or worthlessness, thoughts of suicide)
• signs of heart problems (swollen ankles, shortness of breath, tightness in the chest, decreased ability to exercise, increased heart rate)
• signs of liver problems (yellow eyes or skin, abdominal pain, dark urine or pale stools, easy bruising)
• signs of Thyroid problems (weight changes, feeling constantly hot or cold, changes in sleep patterns)
• signs of unusual infections (symptoms may include fever or chills, severe Diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, loss of voice, weight loss, or listlessness)
• signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine, change of urine colour)
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• skin rash
• swelling in ankles or legs

Stop taking the medication and seek immediate medical attention if any of the following occur:

• seizures
• signs of a serious allergic reaction (e.g., difficulty breathing; Hives; swelling of the face, tongue, or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Betaseron (Interferon-beta-1b).

Each vial contains 0.3 mg of interferon beta-1b (9.6 MIU). Nonmedicinal ingredients: Albumin human USP and mannitol US. Each prefilled diluent syringe contains sodium chloride 0.54%.

Do not use interferon beta-1b if you:

• are allergic to interferon beta-1b or any ingredients of the medication
• are or may be pregnant
• have severe Depression or ideas of self harm
• have severe liver disease

Do not give Betaseron (Interferon-beta-1b) to children and adolescents less than 18 years of age.

There may be an interaction between interferon beta-1b and any of the following:

• theophyllines (e.g., Aminophylline, Oxtriphylline, Theophylline)
• zidovudine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Betaseron (Interferon-beta-1b). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Betaseron (Interferon-beta-1b).

Blood counts: Betaseron (Interferon-beta-1b) can decrease the number of neutrophils (a type of white blood cell that helps fight infection) and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, contact your doctor immediately.

Depression: Depression has been reported by some people taking interferon medications. If you have a history of depression, discuss with your doctor how Betaseron (Interferon-beta-1b) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Betaseron (Interferon-beta-1b), and whether any special monitoring is needed.

If you have depression you should be closely monitored by your doctor. If symptoms of depression such as poor concentration, changes in weight, changes in sleep, decreased interest in activities, or thoughts of suicide occur while taking Betaseron (Interferon-beta-1b) contact your doctor as soon as possible. If you notice any of these symptoms in a family member who is taking Betaseron (Interferon-beta-1b) contact your doctor as soon as possible.

Heart problems: Betaseron (Interferon-beta-1b) may worsen symptoms of heart disease. If you have heart disease such as Angina, Congestive Heart Failure, or arrhythmia, discuss with your doctor how Betaseron (Interferon-beta-1b) may affect the medical condition, how the medical condition may affect the dosing and effectiveness of Betaseron (Interferon-beta-1b), and whether any special monitoring is needed. Contact your doctor as soon as possible if you develop symptoms of heart problems such as shortness of breath, chest pain, rapid heartbeat, or swollen ankles.

Kidney function: Interferon beta 1-b can cause changes to kidney function. If you have decreased kidney function, discuss with your doctor how Betaseron (Interferon-beta-1b) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Betaseron (Interferon-beta-1b), and whether any special monitoring is needed.

If you experience puffy hands, face or feet, high blood pressure, unusual muscle cramping, or darkened urine, contact your doctor as soon as possible.

Liver function: Betaseron (Interferon-beta-1b) may cause severe liver damage. Although rare, this side effect can be very serious. If you have a history of poor liver function, alcohol abuse, or active liver disease, discuss with your doctor how Betaseron (Interferon-beta-1b) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Betaseron (Interferon-beta-1b), and whether any special monitoring is needed.

Your doctor will test your liver function regularly while you are taking Betaseron (Interferon-beta-1b). Contact your doctor as soon as possible if you notice any of the signs of liver damage, including yellow eyes or skin, easy bruising of the skin, nausea and vomiting, itching, or abdominal pain.

Pancreatitis: Betaseron (Interferon-beta-1b) may cause inflammation of the pancreas (pancreatitis). If you have a history of pancreatitis or are at risk for developing pancreatitis, discuss with your doctor how Betaseron (Interferon-beta-1b) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Betaseron (Interferon-beta-1b), and whether any special monitoring is needed. If you develop signs of pancreatitis (e.g., upper left abdominal pain, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen), contact your doctor.

Seizures: Some people have had seizures while taking Betaseron (Interferon-beta-1b), including patients who have never had seizures before. It is not known whether the seizures were related to the effects of their MS, to the medication, or to the combination of both. If you have a seizure disorder, discuss with your doctor how Betaseron (Interferon-beta-1b) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Betaseron (Interferon-beta-1b), and whether any special monitoring is needed. If you have a seizure while taking Betaseron (Interferon-beta-1b), you should call your doctor right away.

Thyroid problems: Some people taking Betaseron (Interferon-beta-1b) develop changes in the function of their thyroid. Symptoms of these changes include feeling cold or hot all the time, a change in weight (gain or loss) without a change in your diet or amount of exercise you get, or feeling emotional. Contact your doctor if you experience these symptoms.

Pregnancy: Betaseron (Interferon-beta-1b) should not be used during pregnancy. If you become pregnant while taking Betaseron (Interferon-beta-1b), contact your doctor immediately. Women who may become pregnant should use effective contraception while taking Betaseron (Interferon-beta-1b).

Breast-feeding: It is not known if interferon beta-1b passes into breast milk. If you are a breast-feeding mother and are taking Betaseron (Interferon-beta-1b), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children and adolescents: The safety and effectiveness of using Betaseron (Interferon-beta-1b) have not been established for children and adolescents less than 18 years of age.