Stelara 90mg Injection contains the active substance Ustekinumab. It is a monoclonal antibody that belongs to the group of medications called interleukin inhibitors. Monoclonal antibodies are specific proteins that identify and bind to certain proteins in the body. It treats moderate to severe plaque psoriasis (skin disease with red and scaly patches on some body areas). It is used alone or in combination with other medicines to treat active psoriatic arthritis (a condition that causes joint pain, swelling, and scales on the skin) in adults.