Chlorcyclizine hydrochloride is primarily used as an antihistamine to treat allergic conditions such as hay fever, hives, and other allergic skin reactions. It works by blocking the effects of histamine, a substance in the body that causes allergy symptoms. Additionally, it has been explored for its potential antiviral properties, particularly in research targeting hepatitis C virus (HCV) due to its ability to inhibit viral entry. In some cases, it is also used to alleviate symptoms of motion sickness and nausea, providing relief from dizziness and vomiting. Its sedative effects make it useful in managing mild anxiety or insomnia in certain patients.