| The highest incidence of adverse reactions associated with AVONEX therapy is related to flu-like symptoms. The most commonly reported flu-like symptoms are myalgia, fever, chills, sweating, asthenia, headache and nausea. Titrating AVONEX at the initiation of therapy has demonstrated a reduction in the severity and incidence of flu-like symptoms. Flu-like symptoms tend to be most prominent at the initiation of therapy and decrease in frequency with continued treatment.Transient neurological symptoms that may mimic MS exacerbations may occur following injections. Transient episodes of hypertonia and/or severe muscular weakness that prevent voluntary movements may occur at any time during treatment. These episodes are of limited duration, temporally related to the injections and may recur after subsequent injections. In some cases these symptoms are associated with flu-like symptoms.The frequencies of adverse reactions are expressed in patient-years, according to the following categories:Very common ( 1/10 patient-years);Common ( 1/100 to <1/10 patient-years);Uncommon ( 1/1, 000 to <1/100 patient-years);Rare ( 1/10, 000 to <1/1,000 patient-years);Very rare (<1/10,000 patient-years);Not known (cannot be estimated from the available data).Patient-time is the sum of individual units of time that the patient in the study has been exposed to AVONEX before experiencing the adverse reaction. For example, 100 person-years could be observed in 100 patients who were on treatment for one year or in 200 patients who were on treatment for half a year.Adverse reactions identified from studies (clinical trials and observational studies, with a period of follow-up ranging from two years to six years) and other adverse reactions identified through spontaneous reporting from the market, with unknown frequency, are provided in the table below.Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.Investigations | common | lymphocyte count decreased, white blood cell count decreased, neutrophil count decreased, hematocrit decreased, blood potassium increased, blood urea nitrogen increased | uncommon | platelet count decreased | not known | weight decreased, weight increased, liver function tests abnormal | Cardiac disorders | not known | cardiomyopathy, congestive heart failure (see section 4.4), palpitations, arrhythmia, tachycardia | Blood and lymphatic system disorders | not known | pancytopenia, thrombocytopenia | Nervous system disorders | very common | headache2 | common | muscle spasticity, hypoesthesia | not known | neurological symptoms, syncope3, hypertonia, dizziness, paraesthesia, seizures, migraine | Respiratory, thoracic and mediastinal disorders | common | rhinorrhoea | rare | dyspnoea | Gastrointestinal disorders | common | vomiting, diarrhoea, nausea2 | Skin and subcutaneous tissue disorders | common | rash, sweating increased, contusion | uncommon | alopecia | not known | angioneurotic oedema, pruritus, rash vesicular, urticaria, aggravation of psoriasis | Musculoskeletal and connective tissue disorders | common | muscle cramp, neck pain, myalgia2, arthralgia, pain in extremity, back pain, muscle stiffness, musculoskeletal stiffness | not known | systemic lupus erythematosus, muscle weakness, arthritis | Endocrine disorders | not known | hypothyroidism, hyperthyroidism | Metabolism and nutrition disorders | common | anorexia | Infections and infestations | not known | injection site abscess1 | Vascular disorders | common | flushing | not known | vasodilatation | General disorders and administration site conditions | very common | flu-like symptoms, pyrexia2, chills2, sweating2 | common | injection site pain, injection site erythema, injection site bruising, asthenia2, pain, fatigue2, malaise, night sweats | uncommon | injection site burning | not known | injection site reaction, injection site inflammation, injection site cellulitis1, injection site necrosis, injection site bleeding, chest pain | Immune system disorders | not known | anaphylactic reaction, anaphylactic shock, hypersensitivity reactions (angioedema, dyspnoea, urticaria, rash, pruritic rash) | Hepatobiliary disorders | not known | hepatic failure (see section 4.4), hepatitis, autoimmune hepatitis | Reproductive system and breast disorders | uncommon | metrorrhagia, menorrhagia | Psychiatric disorders | common | depression (see section 4.4), insomnia | not known | suicide, psychosis, anxiety, confusion, emotional lability | 1Injection site reactions including pain, inflammation and very rare cases of abscess or cellulitis that may require surgical intervention have been reported.2The frequency of occurrence is higher at the beginning of treatment.3A syncope episode may occur after AVONEX injection, it is normally a single episode that usually appears at the beginning of the treatment and does not recur with subsequent injections.Paediatric population: Limited published data suggest that the safety profile in adolescents from 12 to 16 years of age receiving AVONEX 30 micrograms IM once per week is similar to that seen in adults. | |