How to calm coughing in a child without using medication?

Environment. Dust free environment, change pillow cases twice a week, no pets in bedroom, change bed sheets once a week, remove rugs in bedroom, ventilate bedroom clean air filters. Try slowing breathing rate down by blowing out like you blowing out a candle to lengthen time of exhaling air. Check with pediatrician.
Honey. Try 1/2 - 1 teaspoon of honey 20-30 minutes before bed. You can also use Vicks BabyRub on his chest and neck. A humidifier may help as well.
Depends on age. if the child is above 1 yr old you can use honey.if he has asthma see his dr and/or use his inhalors.if the heat is on use a cool mist humidifier--depends how old the child is.