Uses: This medication is used to treat certain types of arthritis (rheumatoid arthritis, arthritis of the spine, psoriatic arthritis), certain bowel diseases (Crohn's disease, ulcerative colitis), and a certain severe skin disease (chronic plaque psoriasis). In these conditions, the body's defense system (immune system) attacks healthy tissues. Infliximab works by blocking the actions of a certain natural substance (tumor necrosis factor alpha) in the body. This helps to decrease swelling (inflammation) and weaken your immune system, thereby slowing or stopping the damage from the disease.