Childhood coughing can be due to many factors, often more than one in a given child. Certainly the most common causes are common colds, more serious respiratory infections like pneumonia, and asthma. Aspirated foreign bodies to the airways, sinusitis and psychogenic cough are other causes.
The typical cough from a cold virus is associated with other symptoms of a cold. These usually include runny nose, sneezing, sore throat and low-grade fever. Often there are other family members who are sick. This type of cough tends to resolve as the cold gets better, but commonly lasts a few days to a week or two after the rest of the cold symptoms go away.
More serious bacterial respiratory infections include pneumonia. Although pneumonia can develop quickly and without a preceding cold, often it complicates a cold or influenza. A typical cold that gets much worse after a few days, with higher fever, cough, often production of a lot of sputum or phlegm, and sometimes with shortness of breath or chest pain is suspicious for pneumonia and is best to be evaluated by your physician.
Croup is a specific type of respiratory viral illness. It is caused by the respiratory syncytial virus (RSV) and other related viruses. It is fairly minor, but can be severe and require respiratory support with oxygen, or rarely mechanical ventilation in an intensive care unit. It tends to be more severe in younger children. In infants, especially premature infants, it can present as a wheezing illness called bronchiolitis that can be more serious.
Asthma tends to cause wheezing also, but can present primarily as a cough. It tends to come in children with a family history of asthma or allergies. Treatment is beyond the scope of this article, but is best discussed with your physician.
Aspiration of a foreign body, like a nut, bead or particle of food can lead to a chronic cough, and although uncommon, can be extremely refractory and needs to be considered in longstanding coughs in children.
Psychogenic cough is uncommon but worth considering, especially when the cough is not associated with other symptoms of illness. It is treated with behavior modification including ignoring and can often be cured with suggestion type therapy.