Neither Optimum Health Care SleePlus TCM nor BYL SleePlus are authorized for sale in Canada, but both have been made available through individual retail outlets in British Colombia.
According to Health Canada, the products - which have the same formulation - have been promoted as sleep aids, but were found to contain undeclared drug clonazepam.
The advisory follows similar events in the past year pertaining specifically to natural health products in Canada, which show that despite the existence of pre-market regulation, some products still slip through the net.
Unlike post-market approval system for dietary supplements in the US, in Canada such products are regulated in a pre-market system that more closely resembles the US' regulatory framework for over-the-counter drugs.
The Natural Health Products Directorate (NHPD), a division of Health Canada, oversees the issuance of licenses to natural health products.
It assesses products for safety, effectiveness and quality, and subsequently issues an eight-digit natural product number for labeling purposes.
Since August 2006, Health Canada has issued advisories for similar products: for Eden Herbal Formulation Serenity Pills II, Salt Spring Herbals
Sleep Well Dietary Supplement, Sleepees and Eden Herbal Formulations Sleep Ease Dietary Supplement.
The four products were allegedly advertised as herbal health products for supporting sleep-related problems, but were found to contain another tranquilizing drug, estazolam.
Canada's licensing system for natural health products involves submitting detailed information about composition and recommended use.
And by their federal definition, natural health products must also have a functional purpose such as mitigating or preventing disease.
Optimum Health Care SleePlus TCM was labeled in Chinese and sold to patients through a clinic in Vancouver, while BYL SleePlus was distributed to retail stores by BYL Pharmaceuticals also in Vancouver.
Both establishments will recall the products.
The fact there is a Chinese link to one of these products is likely to raise a few eyebrows amidst recent controversy surrounding imports from the country.
Highly publicized contamination scares involving imports from China have been leading some suppliers to take extra precaution in testing their ingredients so as to calm manufacturers and distributors.
A recent spate of contamination incidents involving products ranging from pet food to toothpaste has drawn attention to the Chinese supply chain and regulations.
This has in turn put pressure on manufacturers to responsibly identify the security of their sourcing.
When this does not take place, government agencies are left to monitor products with suspicious ingredients if and when they come under their radar.