Protracted anaphylaxis developed after peginterferon α-2a administration for chronic hepatitis C

Peginterferon is a key drug used to treat chronic viral hepatitis that is known for causing various side effects. Side effects occurring immediately after administration include headache, nausea, and influenza-like symptoms, such as fever and joint pain. However, reports of anaphylactic shock are extremely rare. Here we report a patient with protracted anaphylaxis who suffered shock symptoms after peginterferon alpha-2a administration for chronic hepatitis C. Although the patient improved temporarily with shock treatment, symptoms of anaphylaxis recurred. As peginterferon is often administered on an outpatient basis, it is important to recognize life-threatening side effects that may develop in a protracted manner.