Children almost 4 years old still drooling common causes are: mouth ulcers, pharyngitis, neurological disorders and so on. 1. Oral ulcers: 4-year-old children who suffer from oral ulcers, such as gum ulcers, sublingual mucosal ulcers, or viral infections, suffering from herpetic pharyngitis, etc., due to the painful stimulation of the ulcers, resulting in increased salivation, the symptoms of drooling. 2. Pharyngolaryngitis: when children suffer from acute and chronic pharyngolaryngitis, due to the inflammatory stimulation of the pharyngeal mucosa, congestion, edema, resulting in pain in swallowing, because they are afraid to swallow, so the symptoms of drooling. 3. Neurological diseases: encephalitis children, can damage the sympathetic nerve and glossopharyngeal nerve that governs the secretion of the salivary glands, facial nerve palsy children due to local nerve function is reduced or disappeared, affecting the salivary glands secretion regulation ability, there will be a drooling situation. Children 4 years old still drooling there are other causes, to go to the hospital in a timely manner, to identify the cause of the disease to give symptomatic treatment to ensure the normal growth and development of children.