Pharmacists can crush Tamiflu capsules and mix them into a syrup for children. (Michael Probst/Associated Press)

There are concerns Canada has a shortage of liquid Tamiflu, the children's version of the antiviral used to treat flu.

"There's been quite a demand for Tamiflu around the world, given the emergence of H1N1, and the manufacturing process for the suspension formulation is actually 25 times longer than for the capsules," said Laura Pagnotta, a spokesperson for Roche Canada, the drug company that makes the medication.

"Globally we've prioritized the capsule manufacturing so that we can meet the greatest need."

A Manitoba man said he had problems getting liquid Tamiflu for his three children, who are under age five, when they were sick with influenza in Winnipeg last week.

Fearing they had swine flu, the father, took his kids to the Winnipeg children's hospital. A doctor suspected the children had the H1N1 virus and prescribed the liquid form of Tamiflu.

"There were a few scary moments there," recalled the man, who doesn't want to be identified because his wife is a health-care worker.

"I'm relentless. I would've called every single pharmacy in the Winnipeg Health Authority 50 times to get my answer."

About 29 hours after receiving the prescription, he found a pharmacist who crushed a capsule of Tamiflu made for adults and mixed it into a syrup for the children.

Manitoba will re-issue an advisory with instructions on how pharmacists can convert the capsules into a child-friendly version of the drug.

"That information had gone out in the spring," said Theresa Oswald, Manitoba's health minister. "We'll be sending another reminder out."

On Monday, the U.S. Centers for Disease Control put out similar guidelines for American doctors and pharmacists.