The mother of a nine-year-old boy says packaging that depicts highly potent cannabis as a "treat" led her son and several classmates at a Halifax school to consume them and become violently ill earlier this week.

Katrina MacDonald, a health-care worker, said in an interview Friday her son threw up multiple times and had to be rushed to the emergency department, while the mother of another child — who spoke on the condition of anonymity — said her child was taken to intensive care for treatment before stabilizing.

MacDonald said she saw four children in hospital due to ingesting the edible, while Halifax police have said five children are believed to have swallowed the product.

The school sent MacDonald an image of the package of "strawberry/grape" edibles branded as "Nerd Bites" that was found at the school after the children became ill.

It has a picture of brightly coloured candies on a green, grassy background, and in small letters underneath indicates to "keep out of the reach of children."

The 43-year-old mother of three said her son and three other children ate the cannabis just before their recess, after they were offered "gummies" by a classmate who had brought the package to school.

MacDonald says the packaging is dangerous for children her son's age who are unaware of the potential danger of cannabis. She said when she arrived at the school her boy was delirious, anxious and crying. The usually healthy child vomited seven times, had a decreased heart rate and his blood pressure fell as emergency staff provided him with fluids intravenously.

"It was incredibly scary," she said.

She said after she saw the photo of the packaging of the product, which was sent to her while her son was in hospital to assist with his treatment, she felt "a sense of disbelief."

"It looks eerily similar to a package of treats that any parent would buy for their child ... There's a small label at the bottom which says THC, but ... my child didn't know what THC was," she said.

Dr. Bruce Crooks, a pediatric oncologist/hematologist at the IWK children's hospital in Halifax, said the amount of cannabis the children were reported to have consumed — about 200 milligrams each — is "a huge dose," that's roughly 20 times the amounts an adult might take as a recreational dose.

He said the drug can cause brain activity to be depressed in children to the level where they may have to be admitted to intensive care and provided ventilation and other life supports.

A spokeswoman for the Nova Scotia Liquor Corp., the only licensed distributor of cannabis products in the province, says it only buys from licensed producers who are regulated by Health Canada and the federal Cannabis Act. The law generally prohibits the promotion of cannabis, and packaging is to adhere to strict requirements including labelling, child-resistant containers and plain packaging that must not appeal to youth, Terah McKinnon wrote in an email.

However, Crooks said products like Nerd Bites are being ordered online and delivered to households by mail.

"Like gummies, they look like candy, they look like energy drinks, they look like any other products that you can have. And the packaging is specifically designed to be appealing," he said.

MacDonald said she believes what happened to her child "could happen to any family." She said schools need to set up a protocol for handling situations when such a product is brought into the school. "Schools may have to start educating children about the dangers at a younger age," she added.

A Health Canada spokeswoman who was asked for comment sent a link to existing federal cannabis regulations, which say that edible cannabis packaging should be "child resistant" and "plain." The label also "must not be appealing to youth."

The Canadian Press was unable to reach the manufacturer of Nerd Bites.

The Canadian Paediatric Society has warned since the legalization of cannabis that the number of young children needing medical care after ingesting the drug has been on the rise. In 2019, the society recommended to the Liberal government "that any product resembling candy/sweets or appealing to children be prohibited."

Authors of a federal review of the Cannabis Act published last week say that while the creation of a regulated, legal market has decreased illegal online sales, there continue to be problems with enforcement of regulations.

"We are concerned with ... the relative ease with which unauthorized online sellers operate," the report says.