A cough syrup high may occur from taking extremely high doses of over-the-counter cough syrup containing DXM or prescription cough syrup containing codeine. Some of the known side effects of a DXM high can include confusion, double or blurred vision, abdominal pain, nausea and vomiting, a rapid heartbeat, numbness of the fingers and toes, mild distortions of colors and sounds, hallucinations, dissociative sensations and a loss of motor control. Known side effects of codeine abuse include addiction, nausea, sedation, stomach bleeding, kidney and liver damage, convulsions, hallucinations, depression, tremors and seizures
