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The general outline of this therapy can be found here: Best natural cough treatment. This is the way how you can stop coughing for good. An additional factor to stop coughing naturally is to use Earthing for grounding the human body to get Earth's electrons to reduce inflammation.
To stop nighttime coughing in a child (or adult as we found out personally), put Vicks Vapor Rub generously on the bottom of the feet at bedtime, then cover with socks. Even persistent, heavy, deep coughing will stop in about 5 minutes and stay stopped for many, many hours of relief.