| The highest incidence of adverse reactions associated with Rebif therapy is related to flu-like syndrome. Flu-like symptoms tend to be most prominent at the initiation of therapy and decrease in frequency with continued treatment. Approximately 70% of patients treated with Rebif can expect to experience the typical interferon flu-like syndrome within the first six months after starting treatment. Approximately 30% of patients will also experience reactions at the injection site, predominantly mild inflammation or erythema. Asymptomatic increases in laboratory parameters of hepatic function and decreases in white blood cells (WBC) are also common.The majority of adverse reactions observed with IFN beta-1a are usually mild and reversible, and respond well to dose reductions. In case of severe or persistent undesirable effects, the dose of Rebif may be temporarily lowered or interrupted, at the discretion of the physician.The adverse reactions reported below are classified according to frequency of occurrence as follows:| Very Common
| 1/10
| | Common
| 1/100 to <1/10
| | Uncommon
| 1/1,000 to <1/100
| | Rare
| 1/10,000 to <1/1,000
| | Very rare
| <1/10,000
| | Not known
| Cannot be estimated from the available data
| Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.The data are obtained from controlled clinical studies in multiple sclerosis and show the frequency of adverse reactions in excess over placebo. Adverse reactions are listed below by frequency of occurrence and by MedDRA System Organ Class. | System Organ Class
| Very common
| Common
| Uncommon
| Not known*
| | Infections and infestations
| | | Injection site abscess
| Injection site infections, including cellulitis
| | Blood and lymphatic system disorders
| Neutropenia, lymphopenia, leucopenia, thrombocytopenia, anaemia
| | | Thrombotic thrombocytopenic purpura/Haemolytic uremic syndrome
| | Immune system disorders
| | | | Anaphylactic reactions
| | Endocrine Disorders
| | | Thyroid dysfunction most often presenting as hypothyroidism or hyperthyroidism
| | | Psychiatric disorders
| | Depression, insomnia
| | Suicide attempt
| | Nervous system disorders
| Headache
| | | Seizures, transient neurological symptoms (i.e. hypoesthesia, muscle spasm, paraesthesia, difficulty in walking, musculoskeletal stiffness) that may mimic multiple sclerosis exacerbations
| | Eye disorders
| | | | Retinal vascular disorders (e.g. retinopathy, cotton wool spots and obstruction of retinal artery or vein)
| | Vascular disorders
| | | | Thromboembolic events
| | Respiratory, thoracic and mediastinal disorders
| | | | Dyspnoea
| | Gastrointestinal disorders
| | Diarrhoea, vomiting, nausea
| | | | Hepatobiliary disorders
| | | | Hepatic failure, hepatitis with or without icterus
| | Skin and subcutaneous tissue disorders
| | Pruritus, rash, erythematous rash, maculo-papular rash
| | Angioedema, urticaria, erythema multiforme, erythema multiforme-like skin reactions, Stevens-Johnson syndrome, alopecia
| | Musculoskeletal and connective tissue disorders
| | Myalgia, arthralgia
| | | | General disorders and administration site conditions
| Injection site inflammation, injection site reaction, influenza-like symptoms
| Injection site pain, fatigue, rigors, fever
| Injection site necrosis, injection site mass
| | | Investigations
| Asymptomatic transaminase increase
| Severe elevations of transaminase
| | | *Adverse reactions identified during post marketing surveillance (frequency not known) Interferon beta has a potential for causing severe liver injury. The mechanism for the rare symptomatic hepatic dysfunction is not known. The majority of the cases of severe liver injury occurred within the first six months of treatment. No specific risk factors have been identified. Treatment with Rebif should be stopped if icterus or other clinical symptoms of liver dysfunction appear (see section 4.4).The administration of interferons has been associated with anorexia, dizziness, anxiety, arrhythmias, vasodilation and palpitation, menorrhagia and metrorrhagia.An increased formation of auto-antibodies may occur during treatment with interferon beta. | |