Codeine or 3-methylmorphine (a natural isomer of methylated morphine, the other being the semi-synthetic 6-methylmorphine) is an opiate used for its analgesic, antitussive, and antidiarrheal properties. Codeine is the second-most predominant alkaloid in opium, at up to 3 percent; it is much more prevalent in the Iranian poppy (Papaver bractreatum), and codeine is extracted from this species in some places although the below-mentioned morphine methylation process is still much more common. It is considered the prototype of the weak to midrange opioids.