The salivary glands of newborn babies are not yet well developed, and the amount of saliva secretion is actually very small. Until after 3~5 months, babies start to drool. Especially after babies start to add complementary foods, with the intake of starchy foods, the salivary glands are stimulated and the amount of saliva secretion begins to increase. And 6 to 12 months is the period when babies are flooded with drool. At this stage, most babies will grow their first milk teeth. Teeth growth will stimulate the nerves in the gums, causing mild swelling and discomfort in the gum tissues and an increase in saliva production. Until 1 to 2 years old, as the baby’s oral depth increases, swallowing ability to strengthen, the baby drooling phenomenon will slowly disappear. Four cases are signs of disease Drooling is a normal physiological phenomenon of the baby. However, the baby in the drooling along with the emergence of several situations, but may be a sign of disease. 1, if the drooling is accompanied by blisters on the corners of the mouth, the baby may have a disease is mouth ulcers or stomatitis. Because mouth ulcers are painful, the baby may refuse to eat or have difficulty swallowing, parents can prepare some soft and rotten food for the baby to eat. 2, if drooling while accompanied by fever, runny nose, may be pharyngitis or tonsillitis, tonsillitis is often accompanied by redness and swelling of the throat, which leads to the baby swallowing difficulties. At this time, parents are advised to let the baby drink more water, and if necessary, go to the hospital for examination. 3, if the drooling is accompanied by mouth ulcers, then the baby suffers from may be chickenpox or hand, foot and mouth disease. After the baby is infected with chickenpox or hand, foot and mouth disease, there may be ulcers in the mouth or tongue, because the ulcers will be very painful, so the baby will show difficulty swallowing, if the baby refuses to eat, you can let the baby drink more milk and rice paste, supplemental nutrition. 4, when the baby drooling at the same time, also accompanied by behavioral abnormalities, such as coma, then parents should pay extra attention. The baby may be suffering from neurological diseases, such as intellectual disability, facial nerve paralysis, meningitis sequelae, etc..