Since your son has asthma, it is important to continue his prescribed inhalers, Budecort 200 and Levolin 50 mcg, exactly as directed, even after the asthma attack has improved. For a cough with mucus, medicines like Piriton or other mucolytic expectorants may help, but it is best to consult your doctor before adding any new medicine to ensure it is safe for a child with asthma. You can also help him at home by encouraging warm fluids, gentle steam inhalation, and keeping him well hydrated, which can help loosen the mucus. If the cough persists, worsens, or is accompanied by wheezing, rapid breathing, or difficulty breathing, contact your doctor promptly, as they may need to adjust his treatment or suggest a more suitable expectorant.