Abstract: We included 24 trials involving 7099 participants. Using the Cochrane 'Risk of bias' tool, we assessed no study as being at low risk of bias for all domains. Many studies were poorly reported, so the risk of selection and detection biases were often unclear. Most studies reported important outcomes incompletely, and we judged them to be at high risk of reporting bias. All but one study enrolled oral poisoning patients in an emergency department; the remaining study was conducted in a pre-hospital setting. Fourteen studies included multiple toxic syndromes or did not specify, while the other studies specifically investigated paracetamol (2 studies), carbamazepine (2 studies), tricyclic antidepressant (2 studies), yellow oleander (2 studies), benzodiazepine (1 study), or toxic berry intoxication (1 study). Twenty-one trials investigated the effects of activated charcoal (AC), administered as a single dose (SDAC) or in multiple doses (MDAC), alone or in combination with other first aid interventions (a cathartic) and/or hospital treatments. Six studies investigated syrup of ipecac plus other first aid interventions (SDAC + cathartic) versus ipecac alone. The collected evidence was mostly of low to very low certainty, often downgraded for indirectness, risk of bias or imprecision due to low numbers of events. First aid interventions that limit or delay the absorption of the poison in the body We are uncertain about the effect of SDAC compared to no intervention on the incidence of adverse events in general (zero events in both treatment groups; 1 study, 451 participants) or vomiting specifically (Peto odds ratio (OR) 4.17, 95% confidence interval (CI) 0.30 to 57.26, 1 study, 25 participants), ICU admission (Peto OR 7.77, 95% CI 0.15 to 391.93, 1 study, 451 participants) and clinical deterioration (zero events in both treatment groups; 1 study, 451 participants) in participants with mixed types or paracetamol poisoning, as all evidence for these outcomes was of very low certainty. No studies assessed SDAC for mortality, duration of symptoms, drug absorption or hospitalization. Only one study compared SDAC to syrup of ipecac in participants with mixed types of poisoning, providing very low-certainty evidence. Therefore we are uncertain about the effects on Glasgow Coma Scale scores (mean difference (MD) −0.15, 95% CI −0.43 to 0.13, 1 study, 34 participants) or incidence of adverse events (risk ratio (RR) 1.24, 95% CI 0.26 to 5.83, 1 study, 34 participants). No information was available concerning mortality, duration of symptoms, drug absorption, hospitalization or ICU admission. This review also considered the added value of SDAC or MDAC to hospital interventions, which mostly included gastric lavage. No included studies investigated the use of body positioning in oral poisoning patients. First aid interventions that evacuate the poison from the gastrointestinal tract We found one study comparing ipecac versus no intervention in toxic berry ingestion in a pre-hospital setting. Low-certainty evidence suggests there may be an increase in the incidence of adverse events, but the study did not report incidence of mortality, incidence or duration of symptoms of poisoning, drug absorption, hospitalization or ICU admission (103 participants). In addition, we also considered the added value of syrup of ipecac to SDAC plus a cathartic and the added value of a cathartic to SDAC. No studies used cathartics as an individual intervention. First aid interventions that neutralize or dilute the poison No included studies investigated the neutralization or dilution of the poison in oral poisoning patients. The studies included in this review provided mostly low- or very low-certainty evidence about the use of first aid interventions for acute oral poisoning. A key limitation was the fact that only one included study actually took place in a pre-hospital setting, which undermines our confidence in the applicability of these results to this setting. Thus, the amount of evidence collected was insufficient to draw any conclusions.

Plain-language summary: In December 2018 we searched for high-quality studies (randomly dividing participants into different treatment groups) investigating treatments for poisoning that laypeople can perform. We found 24 studies with 7099 participants. All but one study took place in hospitals; the remaining one was in a home setting. Fourteen studies either did not specify the type of poison or studied different kinds. The others investigated overdoses of specific medicines (paracetamol, carbamazepine, antidepressant, benzodiazepine) or poisonous plants (yellow oleander or poisonous berries). Twenty-one trials studied different treatments with activated charcoal: as a single dose or multiple doses, with or without other first aid treatments (a substance to speed up bowel transit), and with or without hospital treatments. Six studies compared syrup of ipecac, with or without other first aid treatments (single-dose activated charcoal plus bowel transit enhancing substance) versus no treatment. We found no studies that investigated the neutralization or dilution of the poison or the use of certain body positions. Two studies compared a single dose of activated charcoal to no treatment following poisoning with paracetamol or different kinds of poisoning. We are uncertain about the treatment's side effects, admission to intensive care or worsening of the patient, and there was no information about effects on death, symptom duration, poison uptake or hospitalization. One study compared a single dose of activated charcoal to ipecac in mixed types of poisoning. We are uncertain about the effect of activated charcoal compared to ipecac, on the patient's level of coma or the number of unwanted effects. There was no information about effects on death, symptom duration, poison uptake, hospitalization or intensive care admission. One study compared ipecac to no treatment in children who ate poisonous berries at home. There may be an increase in the number of unwanted effects for ipecac. There was no information about effects on death, poisoning symptoms, symptoms duration, poison uptake, hospitalization or intensive care admission. We also investigated the use of single-dose or multi-dose activated charcoal, with or without hospital treatment, compared to each other or no treatment. Furthermore, we investigated the added value of ipecac to single-dose activated charcoal and the added value of adding bowel transit enhancing substances to AC. All but one study took place in a hospital setting, which means that the results cannot be directly applied to the lay setting. Because studies did not always report the methods they used, we are uncertain about the quality of the research conduct for many. Outcomes important to patients and pre-specified by us as important outcomes for this review were often absent or incompletely reported. Our certainty about the results of this review is mostly low to very low. Therefore future research is highly likely to change the findings. Based on the identified evidence, we cannot draw any conclusions about the effects of any of the investigated first aid treatments in a lay setting.