• cause
  • It acts on certain centers in the brain to give you pain relief.Butorphanol can also block the effects of narcotics and can cause withdrawal symptoms in people dependent on narcotics. (medicinenet.com)
  • Caution should be used if butorphanol is administered in addition to other narcotics, sedatives, depressants, or antihistamines as it will cause an additive effect. (wikipedia.org)