Morphine and other morphine-like drugs such as buprenorphine, oxycodone and fentanyl are the strongest painkillers available, as of 2015. A doctor or a pain specialist prescribes these drugs to treat severe pain when weaker painkillers have failed to work, according to NHS Choices.
Strong painkillers are used as part of a long-term plan to manage pain, and users are closely monitored. Strong painkillers such as morphine belong to a category called opioids. They are available as tablets, capsules, liquids, injections and patches for the skin. Opioids are available in different brand names, and a patient should not switch from one brand to another unless instructed by a doctor to do so, according to Patient.