If a four-month-old baby has a cough and a runny nose, it usually doesn’t heal on its own, but it’s important to analyze the situation on a case-by-case basis, and you can’t generalize. If a four-month-old baby has just started to have a little runny nose and an occasional cough, with careful care and keeping the air fresh and the temperature right, some children will slowly recover, but the vast majority of children will continue to have a runny nose and cough, or even worsen, if they are left untreated, a situation that needs attention. Sometimes it is necessary to find a doctor to take a look, look at the nasal cavity, listen to the lungs for any other conditions, and if treatment is needed, it should be treated, if not, the doctor will explain how to take care of the child. If a four-month-old infant has a cough and runny nose, keep the nasal passages open as much as possible. If an infant has a stuffy nose, use a warm washcloth on the nose, and in severe cases, use ephedrine-free nasal drops as prescribed by your doctor.