New toxicology results show how Upstate NY mom, grandma died after poisoning four young children

An Upstate New York mom and grandma used a common allergy medication to kill themselves after fatally poisoning four young children, new toxicology results show.

Amy Steadman, 64, and her daughter, Sarah Myers, 44, consumed “fatal or lethal levels” of diphenhydramine – an antihistamine – during the horrific June murder-suicide, the Mechanicsville Police Department told The Post Friday.

The sick mother-daughter duo also gave Myers’ four children – Harper, 13; Hudson, 11, and 10-year-old twins Gracelynn and Gavin Harmon – lethal amounts of the allergy medication, Chief Bill Rabbitt said.

The toxicology reports also found the youngsters all had mitragynine – a compound found in Kratom – in their systems, according to police and reports.