5 months baby has been drooling, can be seen in physiological reasons, such as gland secretion, pre-teething, and so on, can also be seen in the mouth ulcers or herpes. 1. Exuberant gland secretion: 5-month-old baby growth and development, the development of salivary glands is also faster, exuberant secretion, at the same time the child’s swallowing function is incomplete, it is too late to swallow will cause the child drooling. 2. Pre-teething: 5-month-olds may also be due to teething, local stimulation leads to more saliva production, swallowing is not as good as will also appear drooling. 3. Mouth ulcers or herpes: ulcers and herpes in the mouth can cause the child to drool more because of the pain, which affects swallowing. 5 months baby has been drooling, there may be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.