How long do I need to use the mouthwash until I see improvement?

A.
Hello. I guess that you are referring to a particular mouthwash with antibacterial effects, something along the lines of Corsodyl ® or Listerine® which work to reduce gingival inflammation? Well, if you have gingivitis, the use of these kinds of mouthwash combined with efficient and maintained tooth bushing (including between the teeth) should give you some results in a few days. If you have a more severe form of gum disease and it has been going on for some time, it can then give you some relative effect but likely to be only temporary. The mouthwashes will not however reach the area under the gum tissue where the infection/inflammation is present. I advise that you go to see your dentist and discuss any concerns you may have about your current oral health.