​Codeine is a common pain reliever that's found in paracetamol (also known as acetaminophen), the active ingredient in over-the-counter pain medications. Codeine belongs to a class of drugs called opioids, which are derived from morphine and codeine Codeine is an opiate anesthetic used to treat mild pain relief. Codeine can come in pill or liquid form. The liquid codeine is mixed with water and sugar for easy consumption. It comes in many different flavor's including grape, orange, lime and cherry.