Biologics are drugs made from living material, like plants, animals, or micro-organisms. They treat inflammatory disorders such as rheumatoid arthritis, Crohn's disease, Psoriasis, and Psoriatic arthritis by interfering with specific parts of the body's immune system, selectively targeting only those pro-inflammatory targets involved in causing disease. Biologics are new medications in the treatment of Psoriasis -- drugs include Alefacept, Efalizumab, Infliximab, Etanercept, Adalimumab, and Ustekinumab. Because these drugs are relatively new, they are expensive and typically only used for moderate to severe Psoriasis, and only after other methods of treatment have failed or the side effects of other medications become intolerable.
Side effects for Biologics are rare and mild. They generally do not disrupt the entire immune system because they are specifically targeted; however, risks for infection, including tuberculosis, is increased while using Biologics.