Three systematic reviews and 2 randomized clinical trials were identified regarding the clinical effectiveness of chlorhexidine oral care in adult patients who were in critical care and being mechanically ventilated. The evidence was of limited quality, with methodological limitations.
 Compared to ozonated water and to Nanosil, chlorhexidine oral care was associated with a significantly higher risk of ventilator-associated pneumonia. Compared to bicarbonate, chlorhexidine oral care was associated with a significantly lower risk of ventilator-associated pneumonia. There was no significant difference in the risk of ventilator-associated pneumonia between chlorhexidine and other agents, such as potassium permanganate, hydrogen peroxide, or miswak.
 There was no significant difference in the risk of mortality between oral care with chlorhexidine and that with other oral care drugs.
 An evidence-based guideline targeting individuals who require assistance on oral care recommended a multi-component oral care protocol. No specific recommendation regarding the use of oral care agents for the prevention of ventilator-associated pneumonia was made because of lack of evidence.
 There is a lack of evidence on the safety or cost-effectiveness of chlorhexidine oral care in adults who are in critical care and being mechanically ventilated.