Quinacrine dihydrochloride is primarily used as an antimalarial agent, effectively treating and preventing malaria infections, especially in cases of drug-resistant strains. It works by interfering with the growth of parasites in the red blood cells, making it a key component in malaria management. Beyond its antimalarial use, it has been employed in the treatment of giardiasis, a protozoan parasitic infection of the small intestine caused by Giardia lamblia. Additionally, it has found application in autoimmune diseases like systemic lupus erythematosus (SLE), where it helps reduce inflammation and modulate immune responses. In research, it is utilized as a fluorescent stain for chromosome analysis and in studies related to prion diseases due to its ability to inhibit prion protein conversion. It has also been investigated for potential antineoplastic effects, such as inhibiting the spread of certain cancer cells through topoisomerase inhibition. Its versatility makes it valuable in both therapeutic and experimental settings. Use should be under medical supervision due to potential side effects.