Fentanyl and morphine are opioid painkillers. Both are used for painful conditions that don’t respond to over-the-counter medications like aspirin or acetaminophen. But fentanyl is 50 to 100 times more potent than morphine.[1] It’s a much more dangerous and addictive option.
Morphine and fentanyl are powerful prescription opioids used for pain relief.
Morphine treats pain triggered by traumatic injury, surgery and cancer.[2] It is a naturally occurring opioid derived from the opium poppy plant.
Morphine can be administered through oral tablets, liquids and injections (intravenously/intramuscularly). It is often thought of as the “baseline” opioid in medicine.
Fentanyl is a synthetic-opioid compound that is much more potent than morphine.[3] It is sometimes used for patients struggling with excruciating pain that can’t be properly treated with less powerful painkillers. In most cases, fentanyl is administered in hospital settings.
Doctors can deliver fentanyl via skin patches, orally dissolving tablets (lozenges) and intravenous injections. While it's helpful for some people, misuse is both common and extremely dangerous.
Dealers lace street drugs with fentanyl, as it's both powerful and easy to make.[3] Contamination is a major contributor to fatal opioid overdoses in the United States.
Opioids bind to dedicated receptors within the brain, spinal cord and other organs. When they’re attached, opioids block pain signals. They also release a neurotransmitter called dopamine.[4]
Dopamine is a powerful chemical associated with feelings of pleasure, release and reward. The brain remembers the feeling that accompanies these massive increases in dopamine, and it can be difficult to ignore the sensation. Many people keep taking these drugs to recreate the experience.
Morphine and fentanyl both belong to the family of opioids, but they are distinct from each other due to their chemical makeup and power. This table can help you understand what sets these two medications apart:
FentanylMorphineDrug ClassNatural opioidSynthetic opioidDrug ScheduleSchedule IISchedule IIBrand NamesDuragesic, Actiq, Sublimaze, IonsysAvinza, MS Contin, Kadian, Oramorph, Duramorph, MitigoCommon UsesChronic pain relief, cancer pain managementPain relief, postsurgical pain managementRouteInjection, oral, transdermal patches, lozengeInjection, oral, transdermal patchesWarningsFDA warning for addiction, overdose, and drug interactions with benzodiazepines and other CNS depressantsFDA warning for addiction, overdose, and drug interactions with benzodiazepines and other CNS depressantsMisuse PotentialVery highVery highCommon Street NamesApache, China Girl, China Town, Dance Fever, Goodfellas, Great Bear, King Ivory, Murder 8, Tango & CashDreamer, Emsel, First Line, God’s Drug, Hows, MS, Mister Blue, Morph, Unkie
Powerful opioids like morphine and fentanyl cause both physical and mental side effects. They can be split into short-term and long-term problems.
Know that some side effects, including life-threatening versions, can take hold when using these drugs even once.
Opioids cause immediate chemical changes within the brain. You may experience euphoria followed by significant drowsiness. At high doses, which can take hold with even tiny amounts of fentanyl, significant respiratory depression appears. These episodes can be life-threatening, as brain cells are starved of oxygen.
People who misuse opioids for long periods can develop severe gastrointestinal problems, including persistent constipation. When people try to quit using opioids, they may experience significant symptoms like nausea, diarrhea and overwhelming drug cravings.
People who misuse opioids with a needle can develop infections, including some that travel to the heart and cause cardiac problems. People may also experience blood-borne infections like HIV and hepatitis.
Short-Term EffectsLong-Term Effects Drowsiness Gastrointestinal problemsSedation Severe constipation Shallow breathing Withdrawal symptoms Brain-cell death Severe drug cravings Euphoria Cardiac problems Overdose Blood-borne infections Low blood pressure Increased overdose risks
Because both drugs have a high potential for addiction, fentanyl and morphine should not be taken casually or without appropriate medical supervision.[6] They have unique addiction risks.
Fentanyl is a stronger drug. It causes bigger reactions within the brain, which is typically associated with a higher addiction risk. However, fentanyl is so strong that it can cause an overdose the first time it is used. Some people don’t survive their first experience with fentanyl.
Morphine is weaker than fentanyl, and that comes with addiction risks. People can take low doses for longer periods without enduring severe drug overdoses. Their repeated use can lead to severe brain changes that lead to addiction. This drug’s weakness can increase your long-term addiction risks.
While fentanyl and morphine are very similar, important differences exist. They include the following:
Peter Manza, PhD received his BA in Psychology and Biology from the University of Rochester and his PhD in Integrative Neuroscience at Stony Brook University. He is currently working as a research scientist in Washington, DC. His research focuses on the role of the brain dopamine system in substance use disorders and in aging. He also studies brain function in obesity and eating disorders.
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