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Empty shelves of children's pain relief medicine are seen at a Toronto pharmacy, on Aug. 17, 2022. The shortage of pediatric medication in Canada last year led to a spike of dosing errors in children in Ontario, new research shows.Joe O'Connal/The Canadian Press

The number of calls to the Ontario Poison Centre from parents who accidentally gave their children too much Tylenol or Advil spiked last fall as Canada experienced a major shortage of over-the-counter liquid pain relievers, new research has found.

The authors of the study, which was published Wednesday in the New England Journal of Medicine, say the increase likely stemmed in part from caregivers making dosing errors as they split or crushed adult pills for young children. Canadian parents may also have misinterpreted the dosing instructions on liquid pain and fever medicine they purchased outside the country, the study suggests.

The researchers found that the increase in calls to the poison centre did not lead to a statistically significant increase in referrals to hospital, meaning the harm came mostly in the form of stress and fear for parents as they encountered bare pharmacy shelves during an unusually brutal respiratory virus season.

Monthly telephone calls to the Ontario

Poison Centre for unintentional dosing errors

of acetaminophen or ibuprofen

Persons 18 years of age or younger (Jan. 2018 – Feb. 2023)

Acetaminophen

Expected

Observed

Start of shortage

125

100

75

50

25

0

2018

2019

2020

2021

2022

‘23

Expected

Observed

Ibuprofen

Start of shortage

50

40

30

20

10

0

2018

2019

2020

2021

2022

‘23

john sopinski/the globe and mail

Source: the new england journal of medicine

Monthly telephone calls to the Ontario

Poison Centre for unintentional dosing errors

of acetaminophen or ibuprofen

Persons 18 years of age or younger (Jan. 2018 – Feb. 2023)

Acetaminophen

Expected

Observed

Start of shortage

125

100

75

50

25

0

2018

2019

2020

2021

2022

Expected

Observed

Ibuprofen

Start of shortage

50

40

30

20

10

0

2018

2019

2020

2021

2022

john sopinski/the globe and mail

Source: the new england journal of medicine

Monthly telephone calls to the Ontario Poison Centre

for unintentional dosing errors of acetaminophen or ibuprofen

Persons 18 years of age or younger (Jan. 2018 – Feb. 2023)

Acetaminophen

Expected

Observed

Start of shortage

125

100

75

50

25

0

2018

2019

2020

2021

2022

Ibuprofen

Expected

Observed

Start of shortage

50

40

30

20

10

0

2018

2019

2020

2021

2022

john sopinski/the globe and mail, Source: the new england journal of medicine

“There was tremendous anxiety and uncertainty among parents and caregivers who couldn’t get medications when they wanted them,” said Jonathan Zipursky, a clinical pharmacologist and toxicologist at Sunnybrook Health Sciences Centre in Toronto and one of the authors of the new study.

“It is possible some kids had pain and fever that went untreated. There was probably an increased burden on the health care system. Sometimes, when people can’t access the drugs they need, they come in to the hospital or emergency room.”

The shortages last fall and winter of children’s Advil, Tylenol and other brands came about because of a huge increase in demand as viruses such as influenza, respiratory syncytial virus (RSV) and rhinovirus roared back after public-health measures designed to control COVID-19 ended. The continued circulation of the virus that causes COVID played a part, too.

The resurgence was particularly hard on children, and Canadian pediatric hospitals were frequently overwhelmed during the 2022-2023 respiratory virus season.

Margaret Thompson, the medical director of the Ontario Poison Centre, which also serves Manitoba and Nunavut, said nurses at the centre began noticing an uptick early last fall in calls about dosing mistakes with acetaminophen and ibuprofen, the active ingredients in Tylenol and Advil, respectively.

That prompted the poison centre – along with other health care organizations – to publish guidelines on the amount of adult medication to give children by weight. It was the only time Dr. Thompson could recall such guidelines being issued in her more than 20 years at the centre, which is housed at Toronto’s Hospital for Sick Children.

The New England Journal of Medicine study analyzed calls to the Ontario Poison Centre for unintentional acetaminophen and ibuprofen dosing errors among people 18 and younger during the worst of the shortages, from August to December, 2022. For comparison, the researchers tallied calls for the same reason in the 4½ years before the fall of 2022, and in January and February of 2023, when the shortages began to ease.

Opinion: There are children’s medicines on shelves but shortage persists

They concluded that during the height of the shortfall of children’s pain and fever relievers in November of 2022, there were approximately twice as many such calls as in the past, even after taking the increased burden of illness into account. “The observed number of calls were above and beyond what we would have expected,” Dr. Zipursky said. Calls about acetaminophen and ibuprofen dosing mistakes tapered off in early 2023, the study found.

Fortunately, Dr. Thompson of the Ontario Poison Centre, said, “very few people were actually sent to the emergency department because of their dosing error. There is a margin of safety when we’re using ibuprofen or acetaminophen.” (The study looked at whether the poison centre recommended a trip to the hospital but couldn’t determine if callers followed that advice.)

As of mid-April, Health Canada has imported more than 4.4 million units of acetaminophen and ibuprofen products for infants and children to help mitigate the shortages. Respiratory viruses such as flu and RSV have retreated – as they typically do in the late spring and summer – and fewer customers seem to be hoarding liquid acetaminophen and ibuprofen now than in the fall, said Barry Power, the acting chief pharmacist officer for the Canadian Pharmacists Association.

“The supply has improved since the dark days of the fall when it was virtually impossible to find the products,” he said. “But it’s not back to prepandemic levels where you could be guaranteed to walk into a pharmacy and find a fully stocked shelf.”

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