We describe adult-onset Kawasaki disease (KD) and review clinical manifestations and treatment guidelines. Our patient is a 20-year-old female who initially presented to an outside hospital for fever, cervical lymphadenopathy, malaise, exudative tonsillitis, and skin eruption. She received antibiotics for suspected exudative pharyngitis, but experienced continued fevers and presented to the UCLA emergency room one week later. She had diffuse petechial macules coalescing into reticulated patches, fingertip peeling, conjunctival injection, oral erosions, and tongue swelling. Despite her age, given her constellation of symptoms, a diagnosis of typical KD was favored. She was started on high dose aspirin and IVIG, with improvement of rash and conjunctivitis. She was discharged on 325mg of aspirin daily with close follow-up. This case highlights the challenge of diagnosing KD in adults. Although this patient had classic symptoms, she was likely misdiagnosed because KD is rare in adults and without validated criteria. Our patient met the pediatric criteria, suggesting these should be considered when clinical suspicion for adult-onset KD is high. Adult-onset KD is most commonly misdiagnosed as toxic shock syndrome or drug-induced hypersensitivity syndrome and these are important to rule-out. Treatment with high-dose aspirin and IVIG is well established and should be initiated promptly.