Doxycyline is a tetracycline antibiotic used to treat infections of urinary tract, acne, gonorrhea, chlamydiosis, periodontitis, etc.

Plaquenil (hydroxychloroquine) is used to treat or prevent malaria, a disease caused by parasites that enter the body through the bite of a mosquito. Plaquenil is also used to treat symptoms of rheumatoid arthritis and lupus erythematosus.

Chloroquine is a medicine used to prevent and treat malaria, a red blood cell infection transmitted by the bite of a mosquito, and to treat some conditions such as liver disease caused by protozoa (tiny one-celled animals).