How do chemotherapy drugs leave the body?

Russell Portenoy, M.D.: It is important to distinguish the direct effects of chemotherapy as it circulates in the body from the long-term effect that can continue after the body has eliminated the chemotherapy through normal metabolic pathways. Most chemotherapy is eliminated from the body fairly quickly, and the fatigue that patients experience after treatment is a prolonged effect that continues long after the chemotherapy is gone. A person should not assume that feeling fatigued means that the chemotherapy is still in the body. As we said before, fatigue has many possible causes and the experience of severe fatigue should be evaluated so that these causes can be identified and treated.