It's your call but keep the dosage low. I would give him Delysum, maybe start out with 1/4 of a teaspoon and see if that helps. You won't find the dosage on the chart because he is too young but it is nothing but a cough suppressant and it's works great! If you don't want to do that you could try to put vicks on his feet and put socks on as well as on his chest, it helps and I have tried it, but nothing works like delsyum. Benadryl is also ok for him, I don't think it is possible to O.D. on it so you could start out with 1/2 tsp and work up to 3/4, this will make him sleepy and stop the drainage from running down his throat, causing him to cough, helping him sleep better. I am no doctor, just a mom that has been through this with my own kids and this is what works for me. My kids are 5 & 6 now, but we have been in daycare for a long time and I know how frustrating it can be when no one gets any sleep because of a cough. Good luck.