The side effects of biological therapy depend on the type of treatment. Side effects include flu-like symptoms such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Some patients develop a rash, and some bleed or bruise easily. In addition, interleukin therapy can cause swelling.Depending on how severe these problems are, hospitalization during treatment may be required for some patients. Side effects are usually short-term and gradually subside after treatment ends.The long-term side effects of the various currently available biological therapies will be better defined with future research from which will also surely emerge new and valuable forms of these treatments.