reduction or outright discontinuation. Common side effects include fatigue, headache, insomnia, depression, mood swings, hair loss, nausea, diarrhea, myalgia and associated skeletal pain, anorexia, fever etc. Relatively rare effects include imbalance of thyroid hormones, xerostomia, thrombocytopenia, hepatomegaly, pharyngitis, cough, psychosis, rashes, arrythmia, anemia etc. Severe side effects may include a range of potentially fatal neuropsychiatric, autoimmune, ischemic, or infectious disorders. Mechanism of action Host genetic factors For genotype 1 hepatitis C treated with pegylated interferon-alfa-2a or pegylated interferon-alfa-2b combined with ribavirin, it has been shown that genetic polymorphisms near the human IL28B gene, encoding interferon lambda 3, are associated with significant differences in response to the treatment. This finding, originally reported in Nature, showed that genotype 1 hepatitis C patients carrying certain genetic variant alleles near the IL28B gene are more likely to achieve sustained virological response after the treatment than others. A later report from Nature demonstrated that the same genetic variants are also associated with the natural clearance of the genotype 1 hepatitis C virus. References External links Peginterferon alfa-2b in the U.S. National Library of Medicine's Drug Information Portal Medicines patent loophole 'found' at the BBC, 2007 PEG-Intron (Peginterferon Alfa-2B) — Platelet Count Decreased from DrugLib.com Immunostimulants Schering-Plough brands Merck & Co. brands World Health Organization essential medicines Wikipedia medicine articles ready to translate