I. What are the manifestations of patients taking a certain nucleoside analog after resistance has occurred? There is a certain chronological order of performance in the body after resistance to nucleoside analogs occurs. The first thing that appears is the increase of viral load: at this time, except for the increase of viral load, the patient will not feel uncomfortable and the index of liver function is normal. There are two types of elevated viral load: one is when the virus has been negative/undetectable and then turns positive/detectable, and the other is when the virus has been detectable and then there is a significant increase in the amount. If the elevated viral load persists for a period of time, there may be a subsequent increase in transaminases, even with abnormal bilirubin. After or at the same time as the elevated aminotransferases, the patient may feel uncomfortable such as weakness and loss of appetite. The time to deal with drug resistance is when an elevated viral load is detected and treatment is adjusted immediately. However, because the liver transaminases are still in the normal range and the patient does not feel uncomfortable at that time, they are not easily detected. However, once liver function has become abnormal or the patient has become significantly uncomfortable, treatment requires the addition of anti-inflammatory and liver-protective drugs along with the adjustment of antiviral drugs. The correct approach for early detection of drug resistance: review the viral load, biochemical indicators, etc. every 3 months. This method may seem to enhance the cost of the examination, but it provides strong protection for patients to apply nucleoside analogues smoothly. Second, many patients should have a drug resistance gene test, what is the meaning and purpose of this test? When drug resistance is not excluded, 2 things should be done: 1. Review the viral load, preferably within 10 days; if the viral load does change as described above, support drug resistance. 2. Test for drug resistance genes, which is direct evidence of drug resistance. This test is designed to detect possible resistance sites after the application of nucleoside analogue drugs. A positive test indicates that the nucleic acid of the virus in the patient’s body has changed and that the inhibitory power of the drug being applied by the patient to this virus has decreased significantly. The antiviral medication should be adjusted at this time.