Chlorhexidine digluconate is a chemical antiseptic and is used in a 0.12–0.2% solution as a mouthwash. However, there is no evidence to support that higher concentrations are more effective in controlling dental plaque and gingivitis. It has anti-plaque action, but also some anti-fungal action. It is especially effective against Gram-negative rods. The proportion of Gram-negative rods increase as gingivitis develops so it is also used to reduce gingivitis. It is sometimes used as an adjunct to prevent dental caries and to treat gingivitis periodontal disease, although it does not penetrate into periodontal pockets well. Chlorhexidine mouthwash alone is unable to prevent plaque, so it is not a substitute for regular toothbrushing and flossing. Instead, chlorhexidine is more effective used as an adjunctive treatment with tooth brushing and flossing. In the short term, if toothbrushing is impossible due to pain, as may occur in primary herpetic gingivostomatitis, chlorhexidine is used as temporary substitute for other oral hygiene measures. It is not suited for use in acute necrotizing ulcerative gingivitis, however. Rinsing with chlorhexidine mouthwash before a tooth extraction reduces the risk of dry socket, a painful condition where the blood clot is lost from an extraction socket and bone is exposed to the oral cavity. Other uses of chlorhexidine mouthwash include prevention of oral candidiasis in immunocompromised persons, treatment of denture-related stomatitis, mucosal ulceration/erosions and oral mucosal lesions, general burning sensation and many other uses.