The mother of an autistic teenage boy who was allegedly chained inside his western Sydney home while she went shopping has not been charged.

A charity worker allegedly found the 16-year-old chained to a bed in his Blacktown house on Tuesday and called emergency services, who freed him.

The 38-year-old mother of five arrived home shortly afterwards and was arrested, but on Wednesday police said she had been released without charge.

The case remains open as authorities liaise with health and welfare departments.

On Tuesday a family friend said the family did not have enough help to look after the boy. She said the boy’s mother cared about him but was tired and had no help.

The boy was taken to Westmead hospital for observation and was released on Tuesday night, a hospital spokeswoman said.

The chief executive of Autism Awareness Australia, Nicole Rogerson, said it was clear the family needed more support.

“It doesn’t shock me, nor surprise me. It just saddens me. It is never OK to restrain or abuse a person with autism,” she told the Seven Network.

She said the boy should have been at school.

“I think we have let this family down.”