1 yo coughing, gagging in sleep

[Schwanengesang]

DS has a cold, presumably giving him a throat full of mucus that is making him gag and vomit. I have held him upright all night as it is worse when he lies down. There is a limit to how many night i can fo this though so was hoping for other suggestions...

My older DD was always like this when younger.
To help ease the cough cold symptoms- steamy water in the room with a couple drops olbas, raise the cot/bed, Vickes on chest and on soles of feet with socks, a dose of piriton (recommended by GP for cough). A combination of all the above should help.
How old is he?