TORONTO -- Shoppers Drug Mart is urging women in Alberta to check the expiry date on their birth control medication as it may be expired.

The retailer said it dispensed the expired drug Alesse 21 to about 100 women in Western Canada between March 16 and April 1, 2015.

Shoppers says it has contacted everyone who was given expired product in British Columbia, Saskatchewan and Manitoba and has offered to replace the product and provided information and counselling.

Shoppers says it has connected with those who were given expired product in British Columbia, Saskatchewan and Manitoba.

The pharmacy says human error at its distribution centre in Calgary resulted in incorrect data entry to the inventory system, and then the expired product was shipped to stores.

For more information and a list of stores in Alberta that may have dispensed the expired Alesse 21 click here.

"We deeply regret this occurrence and apologize unreservedly to all those affected," the company said in a news release Monday afternoon.

"Our patients' well-being and trust are of foremost concern and guide our business decisions and processes. Shoppers Drug Mart has launched a review of its internal protocols to determine how to prevent errors of this kind in future."