I have suffered a severe injury and i have undergone neurosurgery and trust me when i tell you i have tried every pain medication to end my agony to find what works best. Trully the answer is finding a doctor who will work with you to let you try each to see what works best. Every pain suffering patient is different and as another posted it is in how your body reacts to the medication. I can take vicodin and it will not work for me as an example and i have also taken lortab and it also did not work for me. Once I found the medication that worked i have not altered from that path in years as finding a way to escape chronic pain is something that is not viewed seriously and doctors are too afraid to help patients. Many even think those who take pain medication are addicts. NOt True! Let them live one month in pain with no relief and  then let them judge. My medication only makes me function as i did prior to my injury and pain and i still suffer break through pain at times and i take it regualarly and as perscribed and it lets me live my life. I hope you have a great doctor who is open, caring, and willing to work with you. Mine gave me small quantities at a time long ago until i discovered what worked. True chronic pain sufferers do not get relief from any pain medication even if they are narcotics which is in our country a shame that so many people, doctors, and pain clinics believe. Every person reacts different and finds relief from something that someone else may not. Best to you on your quest to find relief from the pain. I have so much sympathy for those who suffer and sadness in those who do not understand. Also in your quest to find what works the life span and half life of medications makes a difference because they metabolize at different rates.