[1] Other common symptoms include large lymph nodes in the neck, a rash in the genital area, lips, palms, or soles of the feet, and red eyes.

[16][30] Kawasaki disease also presents with a set of mouth symptoms, the most characteristic of which are a red tongue, swollen lips with vertical cracking, and bleeding.

[4][16] Later, during the convalescent or the subacute phase, desquamation of the fingers and toes usually begins in the periungual region within two to three weeks after the onset of fever and may extend to include the palms and soles.

[24] Myocarditis,[45] diarrhea,[32] pericarditis, valvulitis, aseptic meningitis, pneumonitis, lymphadenitis, and hepatitis may be present and are manifested by the presence of inflammatory cells in the affected tissues.

[44] If left untreated, some symptoms will eventually relent, but coronary artery aneurysms will not improve, resulting in a significant risk of death or disability due to myocardial infarction.

[32] In developed nations, it appears to have replaced acute rheumatic fever as the most common cause of acquired heart disease in children.

[64] There is also late-onset aortic or mitral insufficiency caused by thickening or deformation of fibrosed valves, with the timing ranging from several months to years after the onset of Kawasaki disease.

[80] Eye changes associated with the disease have been described since the 1980s, being found as uveitis, iridocyclitis, conjunctival hemorrhage,[81][82][83] optic neuritis,[70] amaurosis, and ocular artery obstruction.

[98][99][100][101] A plausible explanation is that it may be caused by an infection that triggers an inappropriate immunologic cascade in a small number of genetically predisposed children.

[104] Since recurrences are unusual in Kawasaki disease, it is thought that the trigger is more likely to be represented by a single pathogen, rather than a range of viral or bacterial agents.

[108] Seasonal trends in the appearance of new cases of Kawasaki disease have been linked to tropospheric wind patterns, which suggests wind-borne transport of something capable of triggering an immunologic cascade when inhaled by genetically susceptible children.

[109] These associations are themselves modulated by seasonal and interannual events in the El Niño–Southern Oscillation in winds and sea surface temperatures over the tropical eastern Pacific Ocean.

[6][112] Genetic susceptibility is suggested by increased incidence among children of Japanese descent around the world, and also among close and extended family members of affected people.

Many other serious illnesses can cause similar symptoms, and must be considered in the differential diagnosis, including scarlet fever, toxic shock syndrome, juvenile idiopathic arthritis, and childhood mercury poisoning (infantile acrodynia).

[9] Infectious and noninfectious conditions requiring consideration include: measles and other viral infections (e.g. adenovirus, enterovirus); staphylococcal and streptococcal toxin-mediated diseases such as scarlet fever and toxic shock syndrome; drug hypersensitivity reactions (including Stevens Johnson syndrome); systemic onset juvenile idiopathic arthritis; Rocky Mountain spotted fever or other rickettsial infections; and leptospirosis.

[3][126][127] Several reported cases suggest that this Kawasaki-like multisystem inflammatory syndrome is not limited to children; there is the possibility of an analogous disease in adults, which has been termed MIS-A.

Some suspected patients have presented with positive test results for SARS-CoV-2 and reports suggest intravenous immunoglobulin, anticoagulation, tocilizumab, plasmapheresis and steroids are potential treatments.

[6][131] Identification of the exact nature of the immune process involved in Kawasaki disease could help guide research aimed at improving clinical management.

[101] Inflammation, or vasculitis, of the arteries and veins occurs throughout the body, usually caused by increased production of the cells of the immune system to a pathogen, or autoimmunity.

[118][137] A recent, consensus-based evaluation of vasculitides occurring primarily in children resulted in a classification scheme for these disorders, to distinguish them and suggest a more concrete set of diagnostic criteria for each.

[citation needed] Intravenous immunoglobulin (IVIG) is the standard treatment for Kawasaki disease[141] and is administered in high doses with marked improvement usually noted within 24 hours.

Because children with Kawasaki disease will be taking aspirin for up to several months, vaccination against varicella and influenza is required, as these infections are most likely to cause Reye syndrome.

[148] Due to the potential involvement of the upregulated calcium-nuclear factor of activated T cells pathway in the development of the disease, a 2019 study found that the combination of ciclosporin and IVIG infusion can suppress coronary artery abnormalities.

In cases of Kawasaki disease refractory to IVIG, cyclophosphamide and plasma exchange have been investigated as possible treatments, with variable outcomes.

However, a Cochrane review published in 2017 (updated in 2022) found that, in children, the use of corticosteroids in the acute phase of KD was associated with improved coronary artery abnormalities, shorter hospital stays, a decreased duration of clinical symptoms, and reduced inflammatory marker levels.

[152] With early treatment, rapid recovery from the acute symptoms can be expected, and the risk of coronary artery aneurysms is greatly reduced.

Untreated, the acute symptoms of Kawasaki disease are self-limited (i.e. the patient will recover eventually), but the risk of coronary artery involvement is much greater, even many years later.

[citation needed] Laboratory evidence of increased inflammation combined with demographic features (male sex, age less than six months or greater than eight years) and incomplete response to IVIG therapy create a profile of a high-risk patient with Kawasaki disease.

[156] This severe outcome may require further treatment such as percutaneous transluminal angioplasty,[157] coronary artery stenting,[158] bypass grafting,[159] and even cardiac transplantation.

[175] Possible explanations could include confusion with other diseases such as scarlet fever, and easier recognition stemming from modern healthcare factors such as the widespread use of antibiotics.