Officials said some tablets might contain more morphine than the label indicates, exposing patients to the potential risk of accidental overdose. Oversized tablets that are noticeably thicker than regular tablets, and which might contain more morphine than the strength indicated, have been found on the Canadian market.

The morphine tablets are taken orally for the relief of severe pain.

Health Canada said symptoms of an overdose include abnormal breathing, dizziness, confusion or extreme drowsiness, cold or clammy skin and abnormally low blood pressure and heart rate. A severe overdose could result in coma, cardiac arrest and death.

The Canadian distributor, ratiopharm, initiated a recall of the tablets after two complaints were received by the U.S. manufacturer, the KV Pharmaceutical Co.