Buy Codeine Online Free Shipping United State Limited Time Offer Click Here To This Link Order Now, It works by altering the way the brain and nervous system respond to pain and other stimuli. Codeine is often combined with other pain relievers like acetaminophen or aspirin to treat pain such as headaches, back pain, or post-surgery discomfort. It can be found in some cough syrups, as it helps reduce coughing by acting on the brain's cough center.