The foster mother of a toddler who drowned while in her care asked if it was OK to give the 22-month-old sleeping tablets, an inquest has heard.
Braxton Slager drowned in a backyard pool at the home of his foster carers in Stanhope Gardens, in Sydney's north-west, in September 2014.
He had been in foster care for just three weeks.
On Wednesday, an inquest at Glebe Coroner's Court was told a toxicology screen found the drug cyproheptadine, an antihistamine, in Braxton's blood.
The drug is not recommended for children under the age of two.
Under questioning by counsel for Braxton's family, Jerry Prus-Butwilowicz, lead investigator Detective Senior Constable Penelope Allen said cyproheptadine could cause sleepiness in some people.
Detective Allen told the court Christopher Martin, the nephew of Braxton's foster father Greg McBride, gave a statement to police after Braxton's death.
Mr Martin told police he recalled a discussion with Braxton's foster mother, Julie Tarlinton, about giving the toddler something to stop crying and better settle in to his new home.
"Braxton was out of his comfort zone," Mr Martin said in the statement.
"I know Braxton was a bit of a handful.
"I recall [his foster mother] asking if it was OK to give Braxton sleeping tablets."
Gerard Craddock, counsel assisting the coroner, put to Detective Allen: "Did [Mr Martin] tell you... there was talk of sleeping pills being given to him, he was really playing up?"
"Yes," Detective Allen replied.
She told the court Ms Tarlinton denied ever giving Braxton any medication other than for diarrhoea.
She said it was disappointing Mr McBride never made himself available to be interviewed about the possible use of sleeping tablets.
Outside the court Braxton's biological father Johnny Slager said the evidence was upsetting.
"Absolutely horrified. My son was drugged. Being drugged."
The inquest is continuing.
