List of products in the National Drug Code with proprietary name . This medication is used to treat moderate to severe pain, including pain from surgery, muscle pain, and migraine headaches. Butorphanol is an opioid pain reliever similar to morphine. It acts on certain centers in the brain to give you pain relief. Butorphanol can also block the effects of opioids and can cause withdrawal symptoms in people dependent on opioids. If possible, people who have recently used opioids in high doses or for a long time should not use butorphanol. (See also Side Effects section.)