What are the manifestations after a patient develops resistance to a nucleoside analog? When resistance to a nucleoside analogue occurs, there is a certain chronological sequence of physical manifestations. The first thing that happens is the increase in viral load: At this time, the patient does not feel uncomfortable except for the increase in viral load, and the liver function indicators are 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 and even bilirubin abnormalities. After or at the same time as the elevated transaminases, 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 hepatoprotective 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 approach may seem to elevate the cost of the test, but it provides strong protection for patients to apply nucleoside analogues smoothly. Many patients are tested for a drug resistance gene. What is the significance 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, supporting drug resistance; 2. Test for the resistance gene, 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.