Fever and rash do not refer to a specific disease, but rather to the accompanying symptoms of fever in babies for a variety of reasons. Usually when the child has a fever, parents are usually very careful to see if there will be some other symptoms, such as diarrhea, joint pain, and so on, and the rash as one of the common accompanying symptoms, how to deal with fever caused by the rash is also very worthwhile for parents to understand and learn. Measles Measles is the most common acute respiratory infectious disease in children caused by measles virus. Typical clinical manifestations include fever, cough, runny nose, conjunctivitis, measles mucous membrane spots and maculopapular rash all over the body, and after the rash subsides, there is hyperpigmentation and bran-like flaking. The most common complications are pneumonia and laryngitis. The disease is highly contagious. The most common age is 6 months to 5 years old, and in recent years there is a significant increase in the number of people under 6 months of age and over 15 years of age. Long-lasting immunity can be acquired after infection. The disease can be circulated throughout the year, with epidemics occurring mostly in winter and spring. Due to the widespread use of measles vaccine, the morbidity and mortality rates of measles have dropped significantly. Scarlet Fever Scarlet fever is an acute infectious disease of the respiratory tract caused by group A beta-hemolytic streptococcus, which produces rash toxin, and is also a common rash disease. Its clinical features include: fever, pharyngitis, diffuse bright red rash all over the body, obvious desquamation or flaky desquamation after the rash recedes, and acute rheumatic fever, glomerulonephritis and other complications that can occur in a few children after 2~3 weeks of the onset of the disease. Patients and carriers are the source of infection, mainly through direct air droplet transmission. The disease occurs throughout the year, but is more common in winter and spring, with the highest incidence in children aged 5-15 years. At present, due to the use of broad-spectrum antibiotics, especially the application of penicillin, there are fewer heavy cases and more light cases. Fever, sore throat and tonsils are congested and enlarged, some have purulent secretion, the rash appears within 24 hours of fever, and the rash is complete within 24 hours, with diffuse redness of the skin, on which there is a millet rash, and there is no normal skin between the rashes, and there may be special signs such as anemic scratching sign, ring-vented pallid circle, pallid line, and poplar tongue, and there is bran-like or lamellar desquamation of the skin after the rash is withdrawn. Severe children with high fever, intensive rash, even hemorrhagic rash, severe systemic toxic symptoms. Surgical scarlet fever children have purulent skin lesions, mild systemic symptoms, often without pharyngeal symptoms, and the rash around the invasion site is the first to appear and is more obvious. Infantile acute rash Infantile acute rash, also known as infantile roseola, is caused by human herpesvirus type 6 infection and is more common in children under 1 year of age. It is characterized by a high fever for 3 to 5 days, followed by a sudden decrease in fever and the appearance of a rash, which usually begins to subside within a few hours and disappears within 2 to 3 days. The rash is more common on the head, face, neck and trunk, and less common on the extremities. The most common clinical description is “the fever goes down and the rash comes out”. Rubella Rubella is caused by the rubella virus. It is a milder form of the disease, with swollen lymph nodes behind the ears and in the occipital region that are painful to the touch. The rash is a red maculopapular rash all over the body, with no hyperpigmentation or flaking after the rash goes away, and has a good prognosis. The rash usually appears about one day after the onset of fever because the symptoms are usually mild and parents don’t need to worry too much. Chickenpox Chickenpox appears within 24 hours of the onset of fever and is caused by the initial infection with the varicella-zoster virus, which occurs mainly on the chest, abdomen, and back, and rarely on the extremities. The form of the rash is variable and is often described as “grandchildren”. Usually, there are no marks, unless the chickenpox breaks out and becomes infected with bacteria. Hand, foot and mouth disease Hand, foot and mouth disease mostly occurs in children under 5 years of age, can cause herpes on the hands, feet, mouth and other parts of the body, the vast majority of the disease is relatively mild, do not need to worry too much, a small number of children can cause myocarditis, pulmonary edema, aseptic meningoencephalitis and other complications. Individuals with severe cases of the disease lead to death if the disease progresses rapidly. The disease is characterized by herpes on the hands, feet and oral mucous membranes or ulcers formed after rupture as the main clinical symptom. Hand, foot and mouth disease is an infectious disease caused by enteroviruses. Kawasaki Disease Kawasaki disease is non-contagious and has an as yet unknown cause. Fever is present for more than 5 days with bilateral conjunctival congestion without exudate. There is congestion of the mucous membranes of the mouth and pharynx, dry and chapped lips, and prune tongue. The hands and feet are red and swollen in the acute phase, with perinail peeling in the subacute phase. Rash mainly in the trunk, maculopapular rash, polymorphic erythema-like or scarlet-like. Cervical lymph nodes are swollen, with a diameter of more than 1.5 cm.The greatest danger of Kawasaki disease is damage to the coronary arteries, which is the main cause of coronary artery disease in pediatric patients and a potential risk factor for coronary artery disease in adulthood.