04/06/2015 08:36 EDT | Updated 06/06/2015 05:59 EDT

Shoppers Drug Mart warns of expired birth control pills

Shoppers Drug Mart is urging customers in Alberta to check the expiry date on birth control pills purchased in the last three weeks.

The medication, called Alesse 21, was dispensed between March 16 and April 1, but expired September 2014.

The company says a mistake was made at its distribution centre in Calgary, leading to the expired pills being shipped to stores in British Columbia, Alberta, Saskatchewan and Manitoba.

About 100 customers received the expired pills.

Shoppers said it called each customer potentially affected by the error, connecting with all patients who were dispensed expired product in British Columbia, Saskatchewan and Manitoba.

Shoppers said it has launched a review of its protocols to determine how to prevent similar errors.