Codeine is a naturally occurring opiate that is used to treat pain and cough. It may also be used as a recreational drug. Codeine can be taken as an oral tablet or dissolved in the mouth to make a lozenge or sucked through the lips. Some people find they have to take it more often or increase the dose than others.

Codeine is a white, crystalline powder and semisolid. It is soluble in water; with an even distribution of solubility over pH 2–6 with a pKa of 5.3 at 25˚C. Codeine is insoluble in chloroform and almost insoluble in ether, diethyl ether, and a mixture thereof..