Codeine is used to treat mild to moderate pain and to relieve cough.^[2] Codeine is also used to treat diarrhea and diarrhea predominant irritable bowel syndrome, although loperamide (which is available OTC for milder diarrhea), diphenoxylate, paregoric or even laudanum (also known as Tincture of Opium) are more frequently used to treat severe diarrhea.^[3]

Codeine is marketed as both a single-ingredient drug and in combination preparations with the analgesic acetaminophen (paracetamol) (as co-codamol, e.g. brands Paracod, Panadeine, Paramol, and the Tylenol with codeine series including Tylenol 3 and 4); with the analgesic acetylsalicylic acid (aspirin) (as co-codaprin); or with the NSAID (non-steroidal anti-inflammatory drug) ibuprofen (as Nurofen Plus). These combinations provide greater pain relief than either agent alone (drug synergy). Codeine is also commonly marketed in products containing codeine with other pain killers or muscle relaxers, as well as codeine mixed with phenacetin (Emprazil With Codeine No. 1, 2, 3, and 4), naproxen, indomethacin, diclofenac and others as well as more complex mixtures including such mixtures as aspirin + paracetamol + codeine ± caffeine ± antihistamines and other agents such as those mentioned above.

Codeine-only products can be obtained with a prescription as a time release tablet (e.g., Codeine Contin 100 mg and Perduretas 50 mg). Codeine is also marketed in cough syrups with zero to a half-dozen other active ingredients, and a linctus (e.g., Paveral) for all of the uses for which codeine is indicated.