In a news release, the CFIA says these incidents do not usually happen during the manufacturing process but, occasionally, when a consumer returns altered products to the store for a refund.
"Infant formula products have been found where the outer cases and containers are intact but the product inside may have the tamper-proof seal broken and may contain a different product (brand and/or variety)," states a notice on CFIA's website.
However, the agency says there have not been any illnesses associated with these complaints.
The CFIA advises people to make sure their infant formula containers have seals that are intact.
It says costumers who suspect a product has been tampered with should not to use it.