Codeine molecule. Computer artwork showing the structure of a molecule of the opiate drug codeine. Codeine is taken as an analgesic (painkiller), antitussive (cough suppressant) and antidiarrhoeal (relief for diarrhoea). As an opiate codeine works by binding to the opiate receptors in different tissues. Codeine is found in low concentrations in opium poppies, but is usually manufactured synthetically. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white), nitrogen (blue), and oxygen (red), with the bonds between them as rods (silver).