Learn about the side effects of codeine, from common to rare, for consumers and healthcare professionals. Codeine is used to manage mild to moderate pain, where treatment with an opioid is appropriate, and when other pain treatments such as non-opioid pain medicines do not treat your pain well enough or you cannot tolerate them. Codeine is an opioid and considered a strong prescription pain medicine. Codeine is a narcotic pain reliever (analgesic) used to treat mild to moderately severe pain frequently combined with Tylenol or aspirin. Common side effects include itching, rash, stomach pain, constipation, shortness of breath, nausea, lightheadedness, and dizziness. Codeine belongs to a class of medications called opiate (narcotic) analgesics and to a class of medications called antitussives. When codeine is used to treat pain, it works by changing the way the brain and nervous system respond to pain. Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is commonly used as a recreational drug. Find patient medical information for Codeine on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Codeine is a type of strong painkiller called an opioid. It's used to treat pain, for example after an operation or an injury. It's often used when other painkillers, such as paracetamol and ibuprofen, have not worked. Codeine can also be used to treat a dry or painful cough or diarrhoea. Codeine can cause serious unwanted effects if taken by adults, children, or pets who are not used to strong narcotic pain medicines. Make sure you store the medicine in a safe and secure place to prevent others from getting it. Codeine is an alkaloid obtained from opium or prepared from morphine by methylation and occurs as white crystals. Codeine effloresces slowly in dry air and is effected by light. Codeine is a type of opioid (a strong painkiller) that is used to treat mild-to-moderate types of pain. It can be particularly useful when painkillers such as paracetamol and ibuprofen have not been effective.