Shoppers Drug Mart says a computer outage affecting all of its 1,300-plus locations is preventing customers paying with their debit cards and using their loyalty points program.
The national pharmacy retail chain, owned by Loblaw Companies, says it started experiencing "intermittent" technical difficulties at all of its stores Monday night.
It says it can still accept cash and credit card payments of up to $300 and that all Shoppers Optimum points from transactions will be added to customers' accounts after the outage is resolved.
The company says it will provide an update later today.
The outage has prompted customers to voice their complaints on Twitter.
Some say they haven't been able to refill their drug prescriptions and others say Shoppers needs to do a better job of communicating with its customers.
The company has been apologizing to customers on Twitter, saying: "Our IT team is working diligently to rectify the problem."
Loblaw operates a network of more than 1,307 stores across the country under the Shoppers Drug Mart/Pharmaprix brand.