Wax 1999.

Methods	Study design: randomized controlled trial Study duration: 27‐month recruitment period Setting: home setting, with telephone support from a poison centre Country: USA Number of individuals randomized: 103 Number of individuals receiving the intervention: 51 Number of individuals receiving the control: 52 Number of individuals lost to follow‐up: 0 Sample size calculated: no information
Participants	Sex: 57 male and 46 female Age: median (range): 2 years (9 months‐5 years) Country (if different from study authors'): NA Type, dose and timing of poisoning: asymptomatic participants with suspected ingestion of a small number (< 6) of potentially toxic berries, including Taxus species (yew), Solanum americanus (nightshade), Ilex species (holly) or unknown berries Exclusion criteria: ingestion of a known other type of berry, > 5 berries ingested, symptomatic when calling poison centre, parents planning transport to healthcare facility regardless of the advice of the poison centre, ingestion of more than 1 type of berry/plant parts, contraindication for syrup of ipecac
Interventions	Intervention arm: Type: syrup of ipecac (+ home observation) Timing: no information Dose: no information Frequency: no information Integrity: no information Control arm: Type: home observation Timing: NA Dose: NA Frequency: NA Integrity: NA
Outcomes	Type (unit): symptom assessment (vomiting, diarrhoea, abdominal pain, drowsiness, agitation) and disposition assessment (ED referral, hospital admission) Timing: 24 h after telephone call to poison centre (intermediate)
Funding	No information
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quote: "The group who called the poison centre on even days of the month received ipecac followed by parenteral/guardian HO. The group that called the poison centre on odd days of the month were assigned to the HO only group" Comment: not an adequate method of randomization
Allocation concealment (selection bias)	High risk	Randomization method does not allow for allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not possible to blind, but might affect subjective symptom outcomes
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome assessors were not blinded, which might influence assessment of subjective symptom outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	No indication of missing data
Selective reporting (reporting bias)	Low risk	Specified outcomes are reported
Other bias	High risk	Only asymptomatic participants included, no confirmation of actual ingestion and uptake, reporting dichotomous outcomes while measuring using an ordinal scale

AC: activated charcoal; APACHE: acute physiology and chronic health evaluation; AUC: area under the receiver operating curve; bpm: beats per minute; CBZ: carbamazepine; ECG: electrocardiogram;ED: emergency department; ICU: intensive care unit; IQR: interquartile range; MDAC: multi‐dose activated charcoal; NA: not applicable; SAPS: simplified acute physiology score; SD: standard deviation; SDAC: single‐dose activated charcoal; SEM: standard error of the mean; SOI: syrup of ipecac; TCA: tricyclic antidepressant; UC: University of California.