What would the long term effects of a oramorph overdose be?

Depends on downtime: Oramorph is a form of morphine. It is available in a sustained release formulation. The problems with this drug are the same with other opioids, namely they can stop breathing. If you stop breathing, you can develop brain damage, a stroke, have a heart attack, or die. As long as you survive your ingestion, the outcome will depend on how long you were without oxygen (if at all.) hope you are well!