As someone with a lifetime of sinus issues this is a constant issue for me. Remedies I use, in no particular order, include:
-Sinus rinse (NielMed and Navage)
-Sudafed
-Nasal spray
-Fisherman's Friend
-Hot lemonade, with a mint tea bag, in a travel mug or thermos bottle.
-Instead of a cough silencer, I wad up a stocking cap and cough into it. Seems to work about the same. I used a cough silencer, stadium cups and Nalgenes stuffed with rags, etc., and they're just one more thing to lose or clank on something. I always have a beanie or spare gloves or something I can cough into.
-Emergen-C
-Theraflu
-Having a hankie to wipe the sniffles away seems to help control post-nasal drip and the resulting coughs.
This problem sucks. Good luck.