Codeine is an opiate and prodrug of morphine used to treat pain, coughing, and diarrhea. It is found naturally in the sap of the opium poppy, Papaver somniferum.[3][5] It is typically used to treat mild to moderate degrees of pain.[3] Greater benefit may occur when combined with paracetamol (acetaminophen) or a nonsteroidal anti-inflammatory drug (NSAID) such as aspirin or ibuprofen.[3] Evidence does not support its use for acute cough suppression in children or adults.[6][7] In Europe, it is not recommended as a cough medicine in those under 12 years of age.[3] It is generally taken by mouth.[3] It typically starts working after half an hour, with maximum effect at two hours.[3] Its effects last for about four to six hours. Codeine exhibits abuse potential similar to other opioid medications.[3]
Common side effects include vomiting, constipation, itchiness, lightheadedness, and drowsiness.[3] Serious side effects may include breathing difficulties and addiction.[3] Whether its use in pregnancy is safe is unclear.[3] Care should be used during breastfeeding, as it may result in opiate toxicity in the baby.[3] Its use as of 2016 is not recommended in children.[8] Codeine works following being broken down by the liver into morphine; how quickly this occurs depends on a person's genetics.[3]
Codeine was discovered in 1832 by Pierre Jean Robiquet.[9] In 2013, about 361,000 kg (795,000 lb) of codeine were produced while 249,000 kg (549,000 lb) were used, which made it the most commonly taken opiate.[10] It is on the World Health Organization's List of Essential Medicines.[11] Codeine occurs naturally and makes up about 2% of opium.