Health authorities in Canada and the U.S. are split on how to warn users about the potential side effects of certain drugs prescribed for Attention Deficit Hyperactive Disorder (ADHD).

Health Canada has added tough new warnings to the labels of Ritalin and similar drugs used to treat ADHD.

The messages will issue a caution to people with a family history of heart problems, those who engage in strenuous activity, and patients taking stimulants.

The exact wording of Health Canada's new warnings is still being finalized.

The warnings are expected to appear on drug labels starting next month, agency spokesman Chris Williams told The Canadian Press.

The new measures were put in place after drug regulators received reports of 25 people in the U.S. - 19 of them children -- who died suddenly between 1999 and 2003.

There have also been 54 reports of heart attacks, strokes, and psychosis among both children and adults who were taking the medication.

However, Toronto psychiatrist Dr. Atilla Turgay, director of the ADHD clinic at the Scarborough Hospital, said that a causal link between the drugs and the sudden deaths has not been found.

According to Turgay, parents of children who use ADHD "should not panic."

"Many of them had pre-existing cardiac problems. So it's difficult to put the blame entirely on the medication," Turgay told CTV.

Turgay doesn't think the news means patients should stop taking ADHD drugs.

"We still feel that many children, adolescents and adults do better with this medication as long as the physicians are able to rule out some of the risks and have a good monitoring of those patients," Turgay told The Canadian Press.

For patients who use ADHD drugs, like 10-year-old Holly Grice, the news of the potential side effects have to be balanced with the drug's benefits.

"It's helped her greatly so if there was any chance of a side effect I would think about stopping it…but it's made such a improvement in her life," Holly's mother, Kim Priestman, told CTV.

Holly's not sure what to make of the stronger warnings.

"If you take a medication and then there are so many side effects to it but it really helps you - - you don't know what to do," Holly said.

ADHD, a neurobiological disorder with a strong genetic component that is marked by poor attention, impulsivity and hyperactivity, affects approximately five per cent of Canadian children.

Meanwhile in the U.S., a federal health advisory panel decided against recommending that the medication bear the strongest type of warning about possible cardiovascular and psychiatric risks posed by the drug.

The pediatric advisory committee of the Food and Drug Administration recommended clearer language on labels, going against the recommendation of another committee that recommended last month the drugs include a stern "black-box" warning.

The intention of the earlier committee was to alert doctors, patients and parents of the possible cardiovascular risk posed by the drugs.

The FDA then asked the pediatric committee for a second opinion, asking members to look at reports that psychosis or mania can occur in some young patients who are taking an ADHD drug at normal doses.

The more recent committee decided that more information and easier-to-understand language would be sufficient to help doctors, patients and parents to use the drugs safely.

"I wouldn't use the word 'tougher,'" said panel chair Dr. Robert Nelson. "'Clearer."'

The Food and Drug Agency usually follows the recommendations of its committees but isn't required to.

The mental health community and others had cautioned the committee to tread carefully before recommending labels carry stronger warnings

Some experts told the panel that strong warnings could lead to confusion, frustration and fear among those who use the drug.

"I suggest confusion, polarizing viewpoints, initial press hysteria. But then what?" asked Julie Zito, a University of Maryland associate professor in pharmacy and psychiatry, according to The Associated Press.

U.S. and Canadian health authorities have been struggling over how to best communicate the risks associated with the medication.

In Canada, two million prescriptions were written last year, and use of the drugs seems to be on the rise.

With a report from CTV's Avis Favaro