A 34-year-old London woman has been charged with drug trafficking while inside a Milton courthouse jail cell.
Halton Regional police say the alleged incident happened on Monday when courthouse officers were alerted to a woman in custody in medical distress.
Officers administered three doses of naloxone and the woman was taken to hospital where she later recovered.
Police say they determined the woman received the substance, believed to be fentanyl, from her cell mate.
Krystle Dickson of London has been charged with trafficking a controlled substance.
She was arrested on Sunday for possession of a controlled substance, possession of property obtained by crime, and failure to comply with conditions of undertaking.
Police allege Dickson had hidden the suspected fentanyl prior to being arrested and trafficked the substance to the victim.