TORONTO — When it comes to costs, there's nothing common about a cold.

American researchers have calculated the common cold's economic toll on the U.S. economy, setting it at a mind-boggling $40 billion US a year. The researchers, from the University of Michigan Health System, did not calculate figures for Canada.

But experts suggest the annual economic burden of head colds in this country isn't chump change either. Between over-the-counter drugs, useless antibiotic prescriptions, doctors' visits and lost work days, colds cost plenty.

"I think that's the take-home message from this ... that common colds have a big burden on both the health-care system and these indirect costs of work absenteeism and staying home from work to take care of your children," said Dr. Doug Manuel, a Toronto physician and public health researcher at the Institute for Clinical Evaluative Sciences.

"And that point, I think, is extrapolatable from the United States to Canada," said Manuel, who was not involved in the research.

The normal rule of thumb for translating American results into a Canadian context - divide by 10 - probably wouldn't work for these figures, however. Manuel noted the cost of seeing a doctor is lower in Canada than in the United States.

The research was published Tuesday in the Archives of Internal Medicine.

Lead author Dr. Mark Fendrick said the researchers set out to capture all the costs relating to colds, looking beyond the easy-to-calculate items like the number of doctor visits made by people suffering from colds. The paper estimated Americans catch a half-billion colds a year.

Missed work days made up the bulk of the costs - $20 billion, the authors estimated. That included days missed because the employee was sick or was home looking after an ailing child.

Doctors' visits for colds cost $7.7 billion a year; a further $4.8 billion was spent on people seeking treatment because their cold had progressed to a sinus, ear or lower respiratory tract infection.

The team found fully 20 per cent of people with colds went to a doctor - a figure Fendrick called "my main surprise from this study."

Modern medicine has made quantum leaps in many areas, but if you go to a doctor with a cold she'll tell you the same thing her predecessors told their patients half a century ago: get lots of rest, drink plenty of fluids, take headache pills for headaches and keep the tissue box close at hand.

The only cure for a cold is time. There are no drugs currently available to shorten the course of a cold.

That doesn't stop people from stocking up on cold medications. The authors estimated Americans spent between $5 and $10 per cold on cough syrups, cold pills, lozenges and other over-the-counter remedies, tallying $2.9 million.

The authors set that estimate by conducting a telephone poll of 4,051 people, asking them about their incidence of colds, doctors' visits for them and the types of remedies they used. Fendrick said the numbers were probably on the low side.

"I wouldn't be surprised if we really did measure every zinc lozenge and vitamin C and everything else that's taken in the context of treating colds or preventing colds that the $40-billion number would be substantially exceeded," he said in an interview.

The authors found $400 million is spent on drugs prescribed to alleviate cold symptoms and a further $1.1 billion was spent filling prescriptions for antibiotics - which are frequently demanded by patients and too frequently prescribed by doctors and absolutely useless against colds.

The cold's innocuous nature - it doesn't kill and rarely turns into anything more serious - is probably the reason researchers and research funders don't pay it much respect. But the paper noted its annual economic impact is greater than that of asthma and osteoporosis and in the same ballpark as hypertension.

"Even though the per-case costs of many high-impact diseases are substantial higher than the cold, the mere numbers of cold episodes quickly elevates a low-cost event to a real economic burden," Fendrick said.

While Manuel found the argument persuasive, he said he was left wondering where the research could lead.

"My beef with this would be: And now what?" Manuel said, noting the nature of the viruses that cause colds means a vaccine to prevent them is unlikely to be developed any time soon.

Even a drug to cure a cold would not be a huge money saver, Manuel said, suggesting it would just shift costs from the indirect column - lost workdays - to the direct one.

"If we do have drugs that come out, are we going to have everyone (with a cold) going to see a doctor as opposed to the 20 per cent? And those drugs are going to be themselves expensive.

"So we won't have a way of preventing it, but we'll have a way of treating it that will then put an increased burden on our health-care system."

The study was funded by Viro-Pharma Inc.