Codeine is a narcotic pain reliever and cough suppressant that should only be used under a doctor's supervision. It can cause side effects like dizziness, nausea, vomiting, constipation, and difficulty breathing. Codeine is often combined with other drugs in cough and cold medicines. It was referred to by nicknames like "lean" and "syrup" on the streets and was mentioned in a song by a rapper who later died from an overdose at age 29. Treatment for codeine addiction typically begins with medically-supervised detox followed by a longer term residential program.