My wife will reliably get acute sinus infections following a cold if she doesn't take decongestants. She is generally aversive to taking any medication, but after 8 sinus infections in one year, she now always takes decongestants when a cold starts.
just like the other person who replied to you, a neti-pot and pseudoephedrine (which you have to go to the pharmacy counter to get in the US, but does not require a prescription).