Hi, Thank you for your query. I can understand your concerns. PEGASYS, peginterferon alfa-2a, is a covalent conjugate of recombinant alfa-2a interferon. The following are some standard precautions: Cardiovascular disorders: Use with caution in patients with preexisting cardiac disease, including hypertension, supraventricular arrhythmias, chest pain, and MI. Colitis: Fatal and nonfatal ischemic and hemorrhagic colitis have been observed. Discontinue use immediately in patients who develop symptoms. Endocrine disorders: May cause or aggravate hypothyroidism and hyperthyroidism. Hyperglycemia, hypoglycemia, and diabetes mellitus have occurred during treatment with peginterferon alfa-2a; therefore, patients with these conditions at baseline, who cannot be effectively treated by medication, should not begin peginterferon alfa-2a therapy. Patients who develop these conditions during treatment and cannot be controlled by medication may require discontinuation of peginterferon alfa-2a therapy. Pancreatitis: Fatal and nonfatal pancreatitis has been observed. Discontinue use in patients who develop symptoms. Renal impairment: Use with caution and adjust dose accordingly. Usually the treating doctor keeps a close watch on potential side effects. You need not worry. Keep in touch with your doctor while on treatment. Regards Dr. T.K. Biswas M.D. Mumbai