Eight-month-old babies coughing with phlegm is usually caused by respiratory tract infection, pharyngitis or allergy, etc. There is no such thing as the most effective treatment, but it can be treated by adjusting the diet, staying away from allergens and using medication. 1. Respiratory tract infection: coughing is a common symptom of respiratory tract infection, you need to give your child more water to ensure that the respiratory tract is moist. If the cough is caused by a virus, it can be cured on its own and does not require special medication. If the combination of bacterial infection, according to the cause of infection using amoxicillin and other antibacterial treatment. 2. pharyngitis: eight months baby cough phlegm may also be due to pharyngitis caused by the need to give the baby as much as possible a light diet, that is, the addition of complementary food to be light, and pay attention to the amount of water, and the use of medication such as amoxicillin for treatment. 3. Allergy: eight months baby cough phlegm, may also be due to the inhalation of gases that cause easy to cause allergies caused by allergens can be away from the allergens and moderate amount of water, pay attention to a light diet. It is recommended that once the parents found eight months after the baby cough phlegm, timely take the child to improve the relevant examination, standardized treatment. Drugs should be used under the guidance of a doctor, do not blindly use drugs.