"this medicine is sadly being used less and less in the emergency rooms. i am tolerant to morphine and allergic to many other pain medications. demerol not only stops the pain but it stops it for a good 14-16 hours  if i am given 100 mg im with 50 mg gravol. i walk out of the er on my own like i took a tylenol. takes a few hours to kick in but when it does i usually get the best 10-12 hours of sleep which helps decrease the pain since i can rest and let my muscles be at rest. i pray they do not discontinue this medicine. it helps many people for break through pain where others don&#039;t, especially for use people with crps and fibromyalgia. it&#039;s a miracle medicine for me. i use this about 3 to 4 times a year if needed for breakthrough pain lasting more than 72 hours."