The product is the combo pack of Rexall Extra Strength Sinus Relief Daytime and Nighttime Caplets, and the lot number is 00058398B.
In the faulty lot, the daytime pills are incorrectly identified as being the nighttime pills and vice versa.
The nighttime formulation includes a sleep aid, so taking them in the daytime could result in drowsiness.
Health Canada says it doesn't know of any injuries related to the use of the pills, but warns taking the nighttime tablets in the day could leave people more prone to accidents.
The medication is made by Vita Health Products; the lot number is printed on the blister pack just above the expiry date.