Doxycycline is a broad-spectrum antibiotic used to treat a wide variety of bacterial infections and some parasitic diseases. It is effective against infections in many parts of the body, including:

• Respiratory tract infections such as pneumonia, bronchitis, sinusitis, and chest infections.
• Skin infections and inflammatory skin conditions like acne, rosacea, perioral dermatitis, and cellulitis.
• Sexually transmitted infections including chlamydia, gonorrhea, and non-gonococcal urethritis.
• Tick-borne diseases such as Lyme disease, Rocky Mountain spotted fever, ehrlichiosis, and other rickettsial infections.
• Other infections like dental infections (periodontitis), eye infections (e.g., trachoma), plague, tularemia, cholera, brucellosis, and certain infections spread from animals.
• Prevention of malaria in travelers to high-risk areas.
• Treatment or prevention of serious infections such as anthrax and plague, including bioterrorism-related exposures.

Doxycycline works by inhibiting bacterial protein synthesis, which stops bacterial growth and helps clear infections. It also has anti-inflammatory effects that help in conditions like rosacea and acne