Acyclovir analysis in blood serum using liquid chromatography–tandem mass spectrometry (LC-MS/MS) is an advanced laboratory test used to measure acyclovir levels, an antiviral drug commonly used to treat infections caused by the herpes virus. This analysis provides accurate information about the concentration of acyclovir in the blood, helping physicians assess treatment effectiveness and adjust appropriate doses for patients. Acyclovir is an important option for treating viral infections, especially in severe or recurrent cases. By using LC-MS/MS technology, this analysis provides fast and precise results, contributing to improved treatment management and ensuring patient safety. It is considered an essential part of caring for patients receiving acyclovir therapy, as it helps prevent potential side effects associated with excessive or insufficient dosing.