The conjunctivae and oral mucosa, along with the skin, become erythematous. Edema is often seen in the hands and feet and one or both of the cervical lymph nodes are often enlarged.

Kawasaki disease presents with set of mouth symptoms, the most characteristic changes are the red tongue, swollen lips with vertical cracking and bleeding. The mucosa of the mouth and throat may be bright red, and the tongue may have a typical "strawberry tongue" appearance.

The most common skin manifestation is a diffuse macular-papular erythematous rash, which is quite nonspecific.

Cervical lymphadenopathy is seen in 50% to 75% of people.

Also, a remittent fever is characteristic of the acute phase of the disease.

In the acute stage of Kawasaki disease, systemic inflammatory changes are evident in many organs. Joint pain (arthralgia) and swelling, frequently symmetrical, and arthritis can also occur. Myocarditis, diarrhea, pericarditis, valvulitis, aseptic meningitis, pneumonitis, lymphadenitis, and hepatitis may be present and are manifested by the presence of inflammatory cells in the affected tissues.

Thus, it affects many organ systems, mainly those including the blood vessels, skin, mucous membranes, and lymph nodes; however its rare but most serious effect is on the heart where it can cause fatal coronary artery aneurysms in untreated children.

Other reported nonspecific symptoms include cough, rhinorrhea, sputum, vomiting, headache, and seizure.

Of the patients with untreated Kawasaki disease, 10-15% develope coronary artery lesions and a greater proportion develop coronary arterial dilation. Kawasaki disease is a major cause of acquired heart disease in children.

Systemic vasculitis is an inflammatory condition affecting both veins and arteries throughout the body, and is usually caused by a proliferation of cells associated with an immune response to a pathogen, or autoimmunity.

Other diseases featuring vasculitis include Polyarteritis nodosa, Wegener's granulomatosis, Henoch-Schönlein purpura, and Churg-Strauss syndrome.

Gastrointestinal complications in Kawasaki disease are similar to those observed in Henoch–Schönlein purpura, such as: intestinal obstruction, colon swelling, intestinal ischemia, intestinal pseudo-obstruction, and acute abdomen.

The neurological complications per central nervous system lesions are increasingly reported. The neurological complications found are meningoencephalitis, subdural effusion, cerebral hypoperfusion, cerebral ischemia and infarct, cerebellar infarction, manifesting with seizures, chorea, hemiplegia, mental confusion, lethargy and coma, or even a cerebral infarction with no neurological manifestations. Other neurological complications from cranial nerve involvement are reported as ataxia, facial palsy, and sensorineural hearing loss. Behavioral changes are thought to be caused by localised cerebral hypoperfusion, can include attention deficits, learning deficits, emotional disorders (emotional lability, fear of night, and night terrors), and internalization problems (anxious, depressive or aggressive behavior).

Kawasaki disease can only be diagnosed clinically (i.e., by medical signs and symptoms). No specific laboratory test exists for this condition. It is difficult to establish the diagnosis, especially early in the course of the illness, and frequently children are not diagnosed until they have seen several health-care providers. 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).

Like other autoimmune diseases, the cause of Kawasaki disease is presumably the interaction of genetic and environmental factors, possibly including an infection.

Many studies support the existence of an infectious trigger for Kawasaki disease including the epidemiology of the disease by seasonal fluctuations and the reported temporal relationship to various infectious agents such as mycoplasma..

Mycoplasma infection and Kawasaki disease.

 C. Leen, S. Ling, Mycoplasma infection and Kawasaki disease, Arch Dis Child 75 (1996) 266-267.

・J.N. Wang, S.M. Wang, C.C. Liu, J.M. Wu, Mycoplasma pneumoniae infection associated with Kawasaki disease, Acta Paediatr 90 (2001) 594-595.

E. Merlin, H. Al Fatuhi, P. Crost, Kawasaki syndrome and Mycoplasma pneumoniae infection, Arch Pediatr 11 (2004) 972-973.