Opium and its forms (which include morphine, heroin, oxycodone, and the synthetic opioid narcotics) lead to an abnormal mental state, which generally involves excessive sleepiness or unconsciousness.

Symptoms depending on how much is taken. Persons who have opium intoxication usually have respiratory (breathing) depression and small pupils.

Severe opiod intoxication can cause you to stop breathing altogether. This is how people die from an overdose of opiods.