Humidifier and honey.
Use lemon and honey mix Or red oil (palm oil ) and sugar mix Good, safe and natural
I third a spoonful of honey once a day and a humidifier
I rub a small amount of Vicks on the feet and place socks on at night. Also what really works is that I chop the purple onion and sprinkle brown sugar, place in a container, It will make its own liquid. It works. A teaspoon should do and can be given every two day until cold and cough is gone.
Orange + salt (heat up the orange) add honey too
Look into homeopathic remedies, like https://www.boironusa.com I grew up on them and finally convinced my partner that they work faster and more effectively than the crap at the store!
Could also try a slice of potato or onion and place it on the bottom of the feet with a sock over
Honey is my #1 for coughs. Just a tiny bit on a spoon.