Entecavir reduces the viral replication number to less than 1000 copies per milliliter. Under normal circumstances, hepatitis B virus replication at a level greater than 1000 copies per milliliter suggests an active hepatitis B virus replication level. It is necessary to initiate antiviral medication in conjunction with aminotransferase level testing and ultrasound results, take entecavir to bring the viral replication level down to a relatively low range, return liver function to normal, and prevent cirrhosis of the liver from occurring. Diarrhea, headache, dizziness, drowsiness, nausea, vomiting, dyspepsia, elevated alanine aminotransferase levels and glutamine aminotransferase levels, and a decrease in platelet count may occur after taking entecavir. Note that patients who are allergic to entecavir or excipient ingredients should not take this drug. For oral entecavir in clinical practice, it is recommended to consult the infection department of a regular hospital or consult a licensed pharmacist.