Adverse effects of Lactic acidosis-
Lactic acidosis and severe hepatomegaly with steatosis have been reported with use of other nucleoside analogs. The most common adverse effects of entecavir have been headache, fatigue, dizziness and nausea. Severe acute exacerbations of HBV have been reported after discontinuation of anti-hepatitis B drugs, including entecavir. Entecavir is not a substrate, inhibitor or inducer of the cytochrome P450 enzyme system. It is carcinogenic in rodents.