Entecavir taken for 5 years usually does not cause serious consequences, but some adverse drug reactions may occur. During the course of entecavir administration, patients may experience adverse reactions such as malaise, headache, dizziness, nausea, vomiting, diarrhea, abdominal pain, muscle aches, insomnia, etc., but the symptoms are generally mild and can resolve on their own without clinical intervention. Entecavir is the current first-line antiviral therapy for the clinical treatment of chronic hepatitis B and hepatitis B cirrhosis, which can effectively reduce the occurrence of liver inflammation, persistent liver necrosis or fibrosis, and delay or reduce the occurrence of liver decompensation, cirrhosis and liver cancer complications, thus improving the quality of life and extending the life cycle of patients. Data from the study showed that the occurrence of drug resistance during long-term treatment with entecavir was relatively rare, with a 5-year cumulative resistance rate of only 1.2% in patients with chronic hepatitis B who chose to be treated with entecavir for the first time, achieving maximum long-term suppression of hepatitis B virus replication. Improvement in liver condition was achieved in patients with hepatitis B on long-term entecavir, with 88% of them showing improvement in liver fibrosis and 40% showing varying degrees of cirrhosis reversal. Therefore, entecavir has a good antiviral effect, facilitates recovery, is safe, and is usually well tolerated by patients and suitable for long-term use. However, it should be noted that the medication should be taken as prescribed by the doctor, and regular review should be done.