Police said Friday the new charges come as a result of their investigation into the woman, who ran a home daycare in Kitchener, Ont., from 2009 to 2011.
With the new charges, she is now accused in the alleged poisonings of eight children and a 32-year-old adult, all residents of Kitchener, or Guelph, Ont.
Police allege a suspect gave them an over-the-counter eye care product containing Tetrahydrozoline that if ingested can cause abnormal drowsiness, low blood pressure, respiratory problems and decreased heart rates, especially in young children.
They said the new incidents occurred in the last several years and involved children between the ages of one day old and two years old. Police said they were discovered after the first two incidents came to their attention when a child in her care got sick in March.
Police spokeswoman Alana Holton said only that some of the new alleged poisonings occurred with children under the woman's care, while others did not. She said investigators believe there may be more alleged victims.
Holton said police won't divulge just how the eye drops allegedly poisoned the eight children and one adult, adding such details will only be released in court.
Christine Allen, 32, is now accused of nine counts each of criminal negligence causing bodily harm and administering a noxious substance.
She's due to appear in court on Nov. 1.
In March the accused was caring for a friend's child who was taken to hospital with "serious physical symptoms" such as breathing difficulties, drowsiness and a decreased heart rate, police said in July when announcing the first batch of charges.
The child recovered but had to be taken back to hospital at a later date with similar symptoms.
Detectives discovered that another child who had been under the woman's care in July 2010 had similar symptoms, and recovered after a few days in hospital, according to police.
Police have said the daycare did not have a name and it's not known how many children Allen cared for during the three years it operated.