Chemotherapy overdose occurs when a patient has a severe toxic reaction to certain chemotherapy drugs, or in some cases, is unintentionally given an excessive dose. Both possibilities are extremely rare. Symptoms include slowed or even stopped heart rate and breathing, and decreased level of consciousness.
Medications like Vistogard (uridine triacetate) can help reverse the effects of chemotherapy drugs like fluorouracil, blocking cell death and damage and save lives if given quickly.