Vancouver police issued a warning to drug users Tuesday night after “large quantities” of prescription drugs were stolen from a pharmacy, including fentanyl — an opiate more potent than heroin.

The robbery took place Nov. 22 after two suspects entered a pharmacy in the 4600 block of Main Street and forced their way behind the counter, where they obtained the medications. Both robbers fled the scene immediately.

Although various drugs were stolen, police are drawing specific attention to the fentanyl patches — often used to treat palliative patients in severe pain — because of the risk they pose to unknowing drug users.

The patches can be ‘cooked’ down and sold on the street. Because of fentanyl’s potency, it can be overwhelming, even for seasoned opiate users.

In May 2013, health officials in B.C. issued their own warning to drug users after more than 24 people died from fentanyl overdoses in the first few months of the year.

Dr. Caroline Ferris treats patients at a Surrey withdrawal treatment centre, and she says there have been a rising number of overdoses associated with fentanyl even more recently.

“Six to eight months, I would think. Certainly since oxycontin left the market for a while. People have been much more creative with opiates. First it was a big rise in heroin use, and now we are seeing more of the fentanyl,” she told CBC News.

“Using the fentanyl, what [users] will find is that it will wear off much quicker, and then they go into worse withdrawal and they start using larger and larger amounts.”

Police are asking anyone with information regarding the theft or who knows the whereabouts of the stolen drugs to call police at 604-717-3200 or Crime Stoppers at 1-800-222-8477.