Honey, lemon and boiling water has always been our family's go-to for a cough. The new thing now is CBD oil (for those of you that live in a pro-Cannabis state.) I rub some on my chest and it seems to settle the rattling. There's also an herbal remedy called, "Clear Lungs," which has helped me a lot as an emergency when I ran out of asthma meds. I wouldn't take it all the time, but for short term, it works well. You can find it at most drug and health food stores.