Assalaamou3alaikum all
Take one drop of black seed oil n have lots of honey after and before too if u want....or just add the drop of black seed oil in a spoon of honey...black seed has a strong taste,,,but if u like it plain, then

N iv heard much good abt cardamom too...
Black seed boosts up immunity in general...
Insha Allah it will help...just say bismillah with loads of faith n it will b off asap inshaAllah...
Cough syrups are mostly sleep inducing
Btw, is the cough productive?or if its just some allergy...check it out with what dic said last time ...then antiallergics, try to ask for those which dont cause sleepiness, or its ok if u sleeping some more
Abt the salt gargles, just make is somewhat concentrated...i dont really know the theory behind it tho
Some people even use black pepper with honey so that it heats up...but im not v.sure abt this one...maybe it could cause irritation in some people
Fee amaanillah