Coughing in 4 months old babies may be due to upper respiratory tract infection, allergies, etc. It will usually heal itself within a week to yi months, but the exact time of healing varies with the cause of the disease and so on. 1. Upper respiratory tract infections: most viral infections will clear up in a week or so, but of all the symptoms caused by colds, cough is usually the last to go away, and often lasts more than two weeks, or even up to a month, and the duration of the symptoms may be shortened after active treatment. 2. Allergy: some infants may be allergic to pollen, dust and other allergies and coughing symptoms, at this time away from the allergen, the symptoms will disappear relatively quickly, usually within half a month can be significantly improved. However, if the infant’s allergic reaction is more severe, with more violent coughing and crying, there may be a risk of suffocation. 4-month-old infants with coughing, parents should be vigilant, it is best to take the child to the doctor in time to take professional targeted treatment to prevent the condition from worsening.