For four year old child recurrent cough indicates lack of immunity and susceptibility to allergens. Modern drugs are good in acute and emergent cases but can t build immunity to resist further cough attacks. Slowly, this may lead to BRONCHITIS and other complications if not treated properly. My own recommendation on the basis of my three decades experience in clinical Ayurveda is that your child needs to strengthen the resistance against allergens, changing season and to clean the pulmonary system of accumulated cough. This is possible only by Ayurveda which may seem slow but action sustains for long. The scheme of treatment is cleansing the cough, raising the immunity and instilling the strength by special herbal combos designed for children by classical Ayurveda. Main ingredient used remains Piper longum herb - may be in in Bachaturbhadrika chooran or 64 prahari Peepal or anything else in combo with some other harmless things as per current condition and history. These are safe, harmless medicines and given with pure honey. One or two weeks treatment will start showing benefits. Steam inhalation is also important. If you agree, pl consult through direct question for further directions. Hope it is helpful.