Police issued a warning Friday after thousands of OxyContin tablets were taken from a business in a west Edmonton industrial park a week ago.
About 5,400 80-milligram painkiller pills were taken and detectives are concerned about the high dosage of each pill.
"If it does get into someone's hands that is not familiar with the drug and they happen to ingest it in any way, it is potentially fatal," said police spokeswoman Patrycia Thenu.
"Even if one pill of the 80 milligram OxyContin is swallowed, it could potentially cause someone to stop breathing or stop their heart."
Police are also seeking the public's help in finding a man they say was caught on surveillance video during the Aug. 26 break-in.
Mahamed Aden Hassan, 24, is wanted on charges of theft and breaking and entering.
Police say he is 5 foot 10, approximately 184 pounds, with brown eyes and black hair.
OxyContin is a prescribed opiate used for pain relief but it is also sold illegally on the streets. There have been four OxyContin thefts in the West Division in the past two months, police said.