The main side effect of chlorpheniramine is that it may cause side effects that depress the central nervous system, such as dizziness, weakness, drowsiness, etc. Therefore, it is not recommended to drive, work at height, or engage in delicate work during the use of chlorpheniramine. During the use of chlorpheniramine, do not also use other drugs with central depressant effects, such as sedative-hypnotic drugs, etc. Because of these adverse effects, chlorpheniramine is recommended to be used at night before going to bed. In addition to adverse reactions such as central depressant effects, chlorpheniramine also has gastrointestinal adverse reactions, such as stomach pain, nausea and vomiting that may occur after taking the drug.