Talk to your doctor! Some of the common side effects of Pegasys (peginterferon alfa 2a) (peg-interferon alfa-2a) are fatigue, depression, headache, fever, low white cell count, muscle pain and chills. However, there are potentially more serious side effects as well. The risk of developing side effects may depend on your other health problems. You should talk to your doctor.
Usually not. In general, once you have finished your treatment with pegasys, (peginterferon alfa 2a) side effects/symptoms that you were having during treatment slowly disappear, but can take up to 6 months and in some instances 1 year although rare. It can result in autoimmune disorders, although this is also rare. I would discuss your concerns with your treating physician for other rare long term side effects.
Flu-like symptoms. Although Pegasys (peginterferon alfa 2a) has been known to make psychiatric symptoms worse and cause some problems with bone marrow suppression (anemia, low white count, low platelets), the most common side effect is flu-like symptoms.