There is high-certainty evidence that short-term (4-6 weeks) and longer-term (6 months) use of chlorhexidine mouthwash in addition to usual toothbrushing and cleaning leads to a large reduction in the build-up of plaque. This mouthwash is also moderately helpful in improving mild gingivitis (inflammation of the gums), but there is not enough evidence about its effectiveness for people with moderate-to-severe gum disease. The most commonly reported side effects include taste disturbance and soreness of  the mouth lining – these don’t last long. Some people may also experience brown staining on their teeth, but this type of staining comes off after scaling and polishing by a dental professional. It is important to weigh up these side effects against the potential benefits to gum health.