Entecavir is mainly used for the treatment of chronic hepatitis B in adults, and entecavir may cause hepatitis B virus to turn negative. Entecavir is mainly indicated for adults with chronic hepatitis B with persistent elevation of serum alanine aminotransferase, active viral replication, and active lesions shown by liver histology, which may inhibit the activity of hepatitis B viral reverse transcriptase, reduce the replication of hepatitis B virus, and ultimately turn hepatitis B into a negative. The main adverse reactions caused by entecavir are nausea, diarrhea, headache, dizziness, abnormal blood creatinine and urea nitrogen. And entecavir needs to be contraindicated in people who are allergic to entecavir or any component of the preparation. The emergence of hepatitis B sex, need through active treatment, adhere to the doctor’s instructions to take antiviral drugs, can appear hepatitis B virus DNA turn negative, the surface antigen of hepatitis B generally will not turn negative, occasionally there will be individual exceptions. It is recommended to take the drug strictly under the guidance of a doctor.