Humira is used to treat inflammatory conditions like Rheumatoid Arthritis, Ankylosing Spondylitis, Crohn’s Disease and Psoriasis. It’s an injected drug and most people need to learn how to inject themselves at home with a injector pen. It’s usually a shot once a week or once every two weeks. It works by dampening down a component of the body’s immune response (called TNF factor) and can affect the immune response to infection too. This means there is an increased risk of bacterial, viral and fungal infection that needs a watchful eye.