Early-stage CLL in asymptomatic cases responds better to careful observation, as there is no evidence that early intervention treatment can alter the course of the disease. Immune defects occur early in the course of CLL and these increase the risk of developing serious infection, which should be treated appropriately with antibiotics. In those with significant symptoms, chemotherapy or immunotherapy may be used. As of 2019 ibrutinib is often the initial medication recommended. The medications fludarabine, cyclophosphamide, and rituximab were previously the initial treatment in those who are otherwise healthy.