Codeine is a painkiller used to treat pain after an operation or an injury. It is also used as an alternative painkiller when others such as aspirin, ibuprofen and paracetamol have failed. It can even treat diarrhoea, but is only available on prescription.
As a narcotic pain-reliever and cough suppressan it can be combined with Tylenol or aspirin for more effective pain relief.
It is also an opiate to treat mild to moderate degrees of pain and can be addictive so dosages should be taken carefully to avoid severe side effects.