In many countries, codeine is only available with a valid prescription from a licensed healthcare provider. This oversight ensures that the medication is used appropriately for conditions such as mild to moderate pain or as a cough suppressant. While some regions have historically allowed low-dose versions to be sold under pharmacist supervision, many are moving toward more restrictive "prescription-only" models to enhance patient safety.

The primary driver of this regulatory change is the recognition of risks associated with misuse, dependency, and the physiological variability in how individuals process the drug. Codeine is metabolized by the liver into morphine. Because of genetic differences, some individuals are "ultra-rapid metabolizers," meaning they process codeine into morphine much faster than others, which can lead to unexpected toxicity even at standard doses. Furthermore, many products containing codeine also include ingredients like paracetamol or ibuprofen. When individuals exceed recommended dosages, they face severe risks of organ damage from these secondary ingredients.

In response to these public health concerns, numerous countries have reclassified codeine products to require a doctor's oversight. The trend in global health policy favors professional medical consultation over-the-counter access. This ensures that a patient's medical history is reviewed, the risks of dependency are managed, and safer alternatives can be explored when necessary.