Background Both the safety and efficacy of biologic therapy may be affected in the presence of highly prevalent chronic viral hepatitis.

Objectives To evaluate the safety and effectiveness of ustekinumab and antitumour necrosis factor therapy in patients with psoriasis and concomitant chronic viral hepatitis.

Methods This was a retrospective, multicentre study. Twenty‐five patients with psoriasis and concurrent hepatitis C virus (HCV) (20 patients) or hepatitis B virus (HBV) (five patients) infection who had received at least one biologic agent (etanercept, 21 treatments; adalimumab, four; ustekinumab, four; infliximab, two) were included. Clinical, imaging and laboratory data were recorded.

Results In the case of HCV infection, the majority of the patients did not exhibit increases in their viral load or serum liver tests. Aspartate aminotransferase, alanine aminotransferase and gamma glutamyl transpeptidase were doubled from the baseline measurement in only one patient treated with etanercept. Two other cases exhibited viral load increases during the follow‐up period. In total, 18 of the 26 treatments achieved a 75% improvement in their Psoriasis Area and Severity Index (PASI 75) score during the follow‐up period. Two patients treated with etanercept were diagnosed with hepatocellular carcinoma. In the case of HBV infection, all of the patients were being treated with antiviral therapy, and none presented significant variations in viral load or serum liver enzymes. All patients achieved a PASI 75 during follow‐up.

Conclusions Biologic therapy was effective and safe for the majority of our patients with HCV and HBV infection, although there may be a risk of reactivation or aggravation. We describe the first cases to receive ustekinumab. The use of biologics should be limited to those cases in which the risk–benefit ratio is justified.