OTTAWA - Health Canada says problems with two types of medical auto-injectors that are used in treating allergic reactions may pose serious health risks to users.

They're the Twinjet 0.3 milligram unit and the Twinjet 0.15 milligram units.

Twinjet is a pre-filled single-use automatic injector containing an epinephrine solution that is used for the emergency treatment of severe allergic reactions, including anaphylaxis. Twinjet has been on the market in Canada since Aug. 1, 2005.

Health Canada says most of the 30 reported cases of their failure have been said to be life threatening and required either emergency room visits or hospital admissions. Twenty-eight patients recovered without major complications, but the outcome of the other two remains unknown.

Health Canada says that the problems involved needles that did not fire with the first dose, plungers that did not depress properly and needles that were either bent or cracked.

In some cases, the auto-injector had a combination of malfunctions and failed to deliver any drug.

Health Canada says it learned that the Twinjet manufacturer changed the product last year and released modified units in Canada beginning last November. The impact of those changes has not yet been determined.