There are obviously many things that can cause a cough but if it's one of those dry, tickle in your throat type of coughs....I've found that boiling water on a stove and just sort of hanging out over top of it taking deep breaths can help.
I suggest bringing the water to a steamy boil and then shut down the flame. Then lean over taking deep breaths through the mouth. Start with small breaths so that you can test to be sure the temperature of the steam isn't too hot and build from there. Just a couple minutes of this should do.
See a doctor, in some areas Pertussis is going around. Try steam, run the hot water in the bathroom and let the steam build up and see if that helps. Sometimes sipping cold or warm water. There is a medication called, Perls that you can get a prescription for that you swallow and it numbs the throat so the tickle feels better for a while.
I know it is hard to listen to someone cough but he really should be seen to rule out something more serious and contagious.