I would like to know what pain killer drugs to avoid when diagnosed with hepititis c.

Ok, I am going to give you this link, as a doctor, I firmly believe a patients pain should be managed, but also must "first do no harm" Narrcotic pain killers and NSAID's can be hard on the liver as this is where they are proccessed. Please note that I do not advocate or recommend the use of illegale drugs.

http://www.letfreedomgrow.com/cmu/chronic_pain_5.htm

If you are not under the care of a physician, you NEED to be.
Antiviral therapy is available as tretament for chronic hepatitis B and chronic hepatitis C Though antiviral therapy is available, it is not recommended for all chronically infected people. Hepatitis Treatment should be determined based on regular monitoring for the development and extent of liver disease. Because of advances in the field of antiviral therapy for chronic hepatitis B and chronic hepatitis C, standards of practice might change, and those with chronic infection should consult with health care providers who are experienced in treating viral hepatitis.

Many people infected with HBV or HCV, especially IDUs, also have other illnesses (such as HIV, alcohol abuse, diabetes, or tuberculosis) and behaviors that put them at risk for other diseases. However, with careful monitoring by a health care team experienced in hepatitis, addiction, and other pertinent conditions, IDUs can be successfully treated. Antiviral therapy for chronic hepatitis B Individuals with chronic HBV infection - those who have tested positive for hepatitis B surface antigen (HBsAg) for at least 6 months - should have an initial evaluation that consists of:

blood tests for liver disease, such as those that measure alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which are enzymes released by damaged liver cells; and
blood tests for the virus (HBeAg, anti-HBe, HBV DNA)