Herpes on the inside of the baby’s mouth is herpetic stomatitis, which is caused by herpes simplex virus type I infection and is mostly seen in infants and young children aged 1-3 years. The onset of the disease has no obvious seasonality, and often occurs in the pharyngeal isthmus, gums, tongue and lips, red lips and adjacent perioral skin. At the onset of the disease, fever can reach 38-40 ℃, 1-2 days after the above parts of the oral mucosa appeared single or clusters of small herpes, diameter of about 2mm, surrounded by a red halo, rapid rupture after the formation of ulcers, with a yellow-white cellulose secretion cover, multiple ulcers can be fused into a large irregular ulcers, sometimes involving the tongue and the pharynx of the soft palate. Due to the severe pain, the baby may show refusal to eat, drooling, irritability, often found only when crying due to refusal to eat. Body temperature returns to normal after 3-5 days and the disease usually lasts 1-2 weeks. The lymph nodes belonging to it are often enlarged or have pressure pain, which can last for 2-3 weeks.