Biologic drugs . Biologics contain human or animal proteins and can block certain immune cells that are involved in psoriasis. They’re usually recommended for people with moderate to severe psoriasis and are administered via an injection or IV infusion. There are currently three types of biologics that can help treat psoriasis, all of which block immune system chemical messengers that promote inflammation called cytokines. The three types of biologics block the cytokines tumor necrosis factor alpha (TNF-alpha), interleukin 12, interleukin 23, and interleukin 17-A (IL-12, IL-23, and IL-17A, respectively).