Waking up with a swollen baby’s mouth is considered to be related to mosquito bites, allergic reactions, viral infections and other causes. 1. Mosquito bites: often occur in summer. When the baby’s lips are mosquito bites while sleeping, it can lead to the phenomenon of mosquito toxin allergy, which occurs angioneurotic edema, so that the lips appear obvious swelling. 2. Allergic reaction: food allergy is more common. When the baby accidentally consumes food that causes allergy, angioneurotic edema can occur when the baby wakes up the next morning, resulting in obvious swelling of the lips, but there is usually no obvious pain. 3. Viral infections: Herpes simplex virus infection is the most common. When a baby is infected with the herpes simplex virus, it can not only lead to symptoms of swelling of the lips, but also obvious burning pain. When a baby wakes up with a swollen mouth, it is recommended that parents immediately take the baby to the hospital, under the guidance of the physician to improve the relevant examination, clear cause, and then help to subside the symptoms of swelling.