My 5yr old LB attracts illness especially colds and coughs. We have normally used the capol plug in but tonight he has developed a dry cough. Ive turned the plug in off and he has settles back to sleep. He is suspected asthmatic just waiting for him to be able to do a peak flow properly. Many have suggested a humidifier instead to keep the air moist. Opinion and recommendations for fighting the constant colds is very much appreciated. TIA