Cold-FX and the flu shot are "clinically proven" to work better together, according to an ad put out by a major Canadian pharmacy, but some experts say the claim lacks solid scientific evidence.

Rexall flyer

The flu Shot and Cold-FX are clinically proven to be better together, according to recent Rexall flyers and in-store signs.

Rexall, which has about 450 outlets across Canada, has a joint advertising campaign (which includes flyers and in-store signs) with Cold-FX promoting the flu shot along with the natural health product, which is a proprietary extract of North American ginseng.

"I thought putting them together was somewhat problematic because it almost put them on an even keel," said Dr. Lynora Saxinger, an infectious disease expert at the University of Alberta. "I was concerned it could be a little misleading."

She said there is abundant evidence that shows the flu shot is effective 60-70 per cent of the time, but not so with Cold-FX. 

A study that would prove that Cold-FX and the flu shot are better together has never been done, according to Saxinger and James McCormack, a professor at the University of British Columbia's faculty of pharmaceutical sciences.

"If you really want to answer the question — does Cold-FX improve the flu shot?, what you'd want to do is have a study of the flu shot, give a whole bunch of people just the flu shot, you'd have to give a whole bunch of people just Cold-FX and then you'd have to give a whole bunch of people the flu shot and Cold-FX and then you'd look to see if there's anything different in the outcome," said McCormack.

The maker of Cold-FX, Valeant Canada, confirms it has not done this type of study.

Flu shot immunization innoculation influenza health syringe needles

A new ad campaign is claiming Cold-FX and the flu shot are clinically proven to work better when used together, but some experts disagree. (Chanss Lagaden/CBC)

Dr. Maxime Barakat, vice-president of medical and regulatory affairs for Valeant Canada, explained Cold-FX does not claim to be as effective as the flu shot, "It's to bring some synergistic or additive effect to the vaccine. Never will we claim that ColdFX is equivalent to the vaccine, because it's not honest to do this and never will Valeant do this."

Reduction of symptoms?

The ad makes a second claim, one about symptoms: "Cold-FX provides further reduction of cold and flu symptoms when taken with a flu shot." McCormack said there is not enough evidence to support this.

"In my opinion, when one critically looks at these studies the evidence does not support that Cold-FX has an effect." He conceded, if there is an effect, it's limited at best. He concurred with an analysis commissioned by CBC-TV's Marketplace in 2012 that concluded you would need to treat 17 people with Cold-FX to prevent one cold.

Lynora Saxinger

Dr. Lynora Saxinger is concerned about Cold-FX and the flu shot being promoted together. (CBC)

Rexall stands behind the ads which it described as a partnership with Cold-FX, but refers all questions about the claims to the manufacturer, Valeant Canada.

"Our claim is to get a flu shot. That's what we're encouraging people to do. The claims that are made by Cold-FX on their particular advertising campaign, that's their messaging, that's their marketing," said Derek Tupling, spokesman for Rexall. 

A vice-president for Valeant said the proof comes from well-designed studies, and the claims are permitted by Health Canada. 

"The vaccine with Cold-FX, you have this reduction, statistically significant and clinically significant in terms of frequency, severity and duration," said Barakat.

One thing Health Canada does not require the company to do is spell out the length of time needed to produce an effect, something Barakat stressed in his interview with CBC News.

Dr. Maxime Barakat

Dr. Maxime Barakat stands behind the claims made by Cold-FX and says the manifacturer has the evidence to prove them. (CBC)

"We are telling people: don't take Cold-FX for three days or five days, thinking that it will manage your current cold or flu. It will minimize by diminishing but it will take more than that for Cold-FX to have a full effect. " Barakat added. "It takes a minimum of eight weeks … up to six months in elderly population with the vaccine." 

Cold-FX pricing varies, but it would cost around $40 for eight weeks and $120 for six months worth of the pills. 

Flu shots are free to patients and generally covered by provincial governments. 

Health Canada said Cold-FX is permitted to claim the product provides further reduction of cold and flu symptoms and  reduces the frequency, severity and duration of cold and flu symptoms when taken with a flu shot. 

Health Canada confirmed Cold-FX was required to support the claims according to the evidence requirements for natural health products making health claims. 

"I just worry that people who don't have the time or inclination to really dig deeper would tend to just believe what they're being told. And there is a strong implication that the product is more effective than it would appear to be based on their own studies," said Saxinger. 

As far as the perceptions Cold-Fx advertising may create, Barakat said  "I don't comment on the perceptions. I comment on the data, the published data, I comment on science."