OTTAWA—Health Canada is warning that some EpiPens may not slide out of their tubes easily, possibly delaying emergency treatment.

The agency says it was advised by Pfizer Canada about the issue, which it says affects some EpiPen and EpiPen Jr auto-injector devices.

Health Canada warns that the problem could delay or prevent emergency treatment, possibly leading to patient disability or even death.

Pfizer Canada says the issue is with the device label, and not with the device itself or the drug it delivers.

EpiPens are used to deliver a dose of adrenalin to patients who are at risk of life-threatening allergic reactions.