Background & Objectives : One of the limitations in management of patients suffering from decreased level of consciousness due to drug poisoning is the inability to interview the patient. The aim of the study was to compare characteristics of the two subgroups of these patients those who had a suicidal attempt history with others.

 Methods: In this cross-sectional study, 19 patients with suicidal attempt history and 66 patients without this history were selected among patients who were admitted for drug poisoning to referral poisoning hospitals in Tehran, Iran, in August, September and October 2009. All of them had decreased level of consciousness due to unknown drug poisoning. Demographics, poisoning characteristics, past medical history and substance use history of the patients were recorded.

 Results: Different between previous history of suicide action with drug material decreased level of consciousness caused by poisoning, was significantly (p=0.04). Mental disease (p > 0.01), number of tablets consumed (p=0.02), interval between drug consumption and emergency forces to reach the place (p= 0.021), described in deliberate self poisoning patients (Self Poisoning) (p=0.001), decreased level of consciousness grade (p=0.046), U.S. fail initial level of consciousness after emergency measures (p=0.02) and the need for health care and advanced next (p= 0.013) in patients with decreased level of consciousness with a history of previous suicide compared with other group were higher. Significant difference between the two age groups (P> 0.05), gender and history of illegal drug use (P> 0.05) did not exist.

 Conclusion: According to these findings, when dealing with patients suffering from decreased level of consciousness due to unknown drug poisoning, paying attention to history of suicidal attempts in these patients can help medical professionals in determining more effective treatment options for them. Medical staff should also record previous suicide as a risk factor in the risk assessment to consider the disease.