Cycloguanil hydrochloride is primarily used as an antimalarial agent. It is effective in the treatment and prevention of malaria, particularly in regions where the parasite has developed resistance to other drugs. The compound works by inhibiting the enzyme dihydrofolate reductase, which is crucial for the synthesis of folate in the malaria parasite, thereby halting its growth and reproduction.

In addition to its antimalarial properties, Cycloguanil hydrochloride has been explored for its potential use in treating other parasitic infections. Research has indicated its efficacy against certain protozoan infections, expanding its application beyond malaria.

The compound is often used in combination with other antimalarial drugs to enhance its effectiveness and reduce the risk of resistance development. It is also utilized in prophylactic regimens for individuals traveling to malaria-endemic areas, providing a preventive measure against the disease.

Overall, Cycloguanil hydrochloride plays a significant role in the management and control of malaria, contributing to public health efforts in combating this widespread and life-threatening disease.