My son recently woke up with a croup cough, difficulty breathing, and stridor. It hit him suddenly and he showed no signs of a cold beforehand. That night he wouldn't take any medicine so I sat up with him in the recliner with the humidifier. Once I turned the humidifier on, he returned to normal breathing with no cough in about 20 minutes. Now I run the air purifier during the day and the humidifier at night. I keep his room as dust-free as I can. I took down the venetian blinds, vacuum often, change bedding... Etc. Also, my son loves honey, so I let him eat as much unprocessed, local honey as he wants. This helps with the allergens. I think, for my son, it was the allergens that caused the croup cough. If you figure out what is causing the cough and treat that, instead of trying to just treat the cough, you can control it more easily.