Police allege that when the woman took the two-year-old boy to Nepean Hospital on December 8 last year, she told hospital staff that the child had consumed paint thinner at their home on Chesterfield Road in South Penrith.

The boy's condition deteriorated and he was flown to the Sydney Children's Hospital at Randwick, where he received specialised treatment and underwent testing.

A NSW Police spokeswoman said forensic analysis and pathology tests revealed the child had consumed illicit drugs, rather than paint thinner.

Detectives from the State Crime Command's Child Abuse Squad launched an investigation into the incident and executed a search warrant at the Chesterfield Road home, where a number of items were seized for forensic examination.

Earlier this month, detectives arrested arrested the 36-year-old woman at Penrith Police Station.

She was charged with two counts of neglect a child in her care, and failing to provide for a child, causing danger of death.

The woman was granted strict conditional bail to appear at Penrith Local Court on Tuesday.

Police could not immediately say whether the woman was the child's mother. The child survived the incident, but police could not say what condition he was in, or what drugs he had consumed.

The Department of Family and Community Services was alerted of the incident, police said.