A four-year-old child with a cold and runny nose is a symptom triggered by weather changes, sudden cold, low immunity of the child and germs infection. Babies with runny nose should pay attention to clean it up in time. Usually, you can apply petroleum jelly to the baby’s external nostrils to lubricate the nasal cavity. If your child’s nose is sticky, consider using a nasal aspirator to help suck out the snot. In addition, if there is significant nasal congestion, you can wash the nasal passages with saline and apply hot towels to the root of the nose to promote smooth breathing. It is also important to closely monitor your child’s temperature changes during the flu. If there is a fever and the temperature continues to rise, take oral antipyretics and warm water baths to help reduce the fever. It is also necessary to keep the air inside the house at the right temperature and humidity, to increase the humidity of the air and to avoid an excessively dry and cold environment to help keep breathing smoothly.