Drug abuse is an increasing phenomenon [13,14,22], also among the young people [5,24,27], with high involvement of the emergency department [17,21,25] and high hospitalization rates [28] and costs. [11] This growing “epidemic” is also spreading because of the misuse of prescribed medications, such as opioids and cannabinoids [15,16].

The length of stay of the patient with acute alcohol intoxication (AAI) in the emergency department (ED-LOS) can be affected by many variables such as the use of diagnostic testing, the need for treatments [38], the hour of arrival [37], and the involuntary holds [35,40].

We present a summary of the most relevant studies published on this topic, starting from epidemiological data, pharmacokinetics and pharmacodynamics, to continue with evidence of potential adverse effects regarding drug abuse. We have analyzed the most important risk factors for hospitalization. However, our review has not identified, to date, a validated protocol that can address the ED physician to choose between discharging and hospitalizing a drug abuser. Nevertheless, many studies of alcohol disorders and drug addiction may be helpful in identifying those patients that, because of their risk factors, may require hospitalization.

Regarding adolescent patients—who make up a large portion of the intoxicated patients—the physician should investigate the age of the starting of alcohol or drug consumption, since the first use of alcohol at a young age (10–14 years) greatly heightens the risk of progression to the development of alcohol disorders. [3,4,5] Moreover, even if ethanol is the most commonly consumed substance, modern illegal recreational substances are also often co-used, and this is why the physician must also investigate about poly-drug use [5,6,8,26]. Poly-drug use, especially with concomitant alcohol consumption, is a “red flag” because it has been reported that this condition is associated with an increase in adverse events, greater consciousness impairment, higher need for care, ICU admission, and longer h-LOS. [39] It is useful, in adolescents, to also evaluate other variables that can predict drug and alcohol abuse, like depression, impulsivity, low self-esteem, delinquent predisposition, low peer insecurity, and history of child abuse [32].

The ED physician has to consider also gender differences [7]. In fact, female drug abusers have higher hospitalization rates and poorer survival, while males have higher h-LO [28]. Moreover, women are more likely to be hospitalized when they are homeless. [33] Young males often come to the ED as police presentations, are often unemployed, and present psychotic disorders [45].

Concomitant diseases that can require hospitalization—like psychosis, schizophrenia, depression, cardiovascular diseases, hepatitis C, HIV, traumatic lesions—have to also be assessed [8,9,10,28,29,30,31,46]. For this reason, the management of the acute intoxicated patient is often multidisciplinary.

Sometimes the ED physician has to postpone the evaluation about risk factors because the patient reaches the emergency department in critical conditions (i.e., consciousness or respiratory impairment, traumatic lesions, psychomotor agitation). It has been demonstrated that awareness and confidence of clinicians can be significantly influenced by targeted training/education. [43] ED physicians should be trained in recognizing the presentation features of the intoxications caused by the main illicit substances and support the vital functions [20,23,25], the indications to the available antidotes [18,19,47], and the prevention of severe withdrawal symptoms [34].

In our experience, for the management of the acute intoxicated patient, we introduce a third option—between discharge and hospitalization—that is part of the emergency department and is managed by the emergency medicine physician: the temporary observation unit (TOU). We have previously reported that the TOU is a good option for the acute alcohol intoxication management [36] since it generally requires less than 24 h with favorable outcome [44]. We suggest that it can be a feasible solution even in the drug abuser, after the exclusion of other medical conditions requiring hospitalization. In the TUO, special attention is given to patients with concomitant mental issues that are evaluated by the consultant psychiatrist, which sets the stage for further clinic follow-up and, if needed, medication therapy. We believe that this strategy may prevent ED low-term and long-term readmission, which have been frequently reported in the literature [41,42]. In fact, many of these patients are not integrated within a support program and have multiple access to the ED [6,7].

From a medico–legal point of view, in order to avoid any medical litigation, hopefully, there should be a standardized protocol in the hospital for the management of intoxicated patients, with adequate training of ED health personnel. In order to reach such standard management, more studies about the prognostic role of the risk factors, should be conducted in the future. In the next years, special effort should be made in educating and training of the ED personnel—possibly including physicians and nurses—hopefully with the development of standardized education programs that include toxicology rudiments. Since the inflow of intoxicated patient is increasing, hospitalization should be reserved to high-risk patients after stabilization in the emergency department. Low-risk intoxicated patients could be managed in a time-effective and resources-effective fashion by the emergency medicine physician in the emergency department, exploiting the potential of the TUO.