Most cough medications that reduce unnecessary cough have an ingredient called dextromethorphan. It helps reduce the tickle in the throat and has few side effects. A physician can prescribe narcotic cough medications that are stronger than dextromethorphan. But at night, something to ease the cough may be helpful. First of all what an adult does is different from what you may do to a small toddler.
Kids get stuffy noses and instead of blowing let it run down their upper lip.
Then they start the cough cycle that can perpetuate itself. If a child is miserable and drizzling all over the place a combination of decongestant and dextromethorphan may help. But don't use combination products that have everything when everything is not indicated. Vaporizers help during the dry winter months and Vicks rubbed on the chest provides a source of decongesting fumes near the nose for prolonged periods of time that are not harmful and worth a try. You can get nose drops that open the nose for eight hours or more and are a good idea at bedtime instead of a decongestant that may keep the child awake.