Kawasaki disease is a syndrome of unknown cause that results in a fever and mainly affects children under 5 years of age. It is a form of vasculitis, where blood vessels become inflamed throughout the body.The fever typically lasts for more than five days and is not affected by usual medications. Other common symptoms include large lymph nodes in the neck, a rash in the genital area, and red eyes, lips, palms, or soles of the feet. Within three weeks of the onset, the skin from the hands and feet may peel, after which recovery typically occurs. In some children, coronary artery aneurysms form in the heart.

While the specific cause is unknown, it is thought to result from an excessive immune system response to an infection in children who are genetically predisposed. It does not spread between people. Diagnosis is usually based on a person's signs and symptoms. Other tests such as an ultrasound of the heart and blood tests may support the diagnosis. Other conditions that may present similarly include scarlet fever and juvenile rheumatoid arthritis, as well as a multisystem inflammatory syndrome in children, an emerging Kawasaki-like disease following COVID-19 which is currently under investigation.