Ustekinumab is a human monoclonal antibody that binds to the shared p40 subunit of interleukin (IL) 12 and IL-23. It is approved in the United States for adults (>18 years) with moderate to severe plaque psoriasis who are candidates for phototherapy or systemic therapy. In 1 phase 2 trial of ustekinumab for treatment of psoriatic arthritis, joint disease improved.