There is no fastest cure for cough and phlegm in infants, it is usually caused by respiratory infections and allergies, which can be relieved by using antibiotic medications and staying away from allergens. Infants with pathogenic infections in the respiratory tract may have increased respiratory secretions and coughs. If the infection is bacterial, it can be treated with antibacterial medications such as cefixime, cefdinir, and other antibacterial medications. If the infant’s cough and phlegm are caused by allergy to the surrounding environment, it is necessary to promptly remove the environmental factors that can easily cause allergy, such as dust, pollen, etc., and pay attention to maintaining indoor ventilation, and can also follow the doctor’s instructions to take oral antihistamines, such as Cetirizine Hydrochloride Drops and so on. If an infant’s cough with phlegm persists and cannot be relieved, it is recommended to go to the hospital in time, under the guidance of the doctor for standardized treatment.