Reiter’s syndrome, now more commonly called reactive arthritis, is an inflammatory condition that develops as an autoimmune reaction following certain bacterial infections, typically in the genitourinary tract (e.g., Chlamydia trachomatis) or gastrointestinal tract (e.g., Salmonella, Shigella, Campylobacter, or Yersinia). It classically presents with a triad of symptoms: arthritis (painful, swollen joints, often affecting knees, ankles, or feet asymmetrically), urethritis (inflammation of the urethra causing painful or frequent urination and discharge), and conjunctivitis (red, irritated eyes). Additional features frequently include skin lesions (such as circinate balanitis on the penis or keratoderma blennorrhagicum on palms/soles resembling psoriasis), mouth ulcers, enthesitis (inflammation where tendons attach to bone, like heel pain), dactylitis (sausage-like finger/toe swelling), and sometimes low back pain from sacroiliitis. It predominantly affects young adults, more often men, and symptoms usually appear 1–4 weeks after the triggering infection, though the inciting infection may have resolved by then.