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Fentanyl vs. Morphine: What’s the Difference?

Both fentanyl and morphine are types of opioid pain relievers, though they are derived from different sources. When used safely, they can provide significant medical benefits. However, when misused, they can have serious health consequences, such as addiction and negative side effects.

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While both fentanyl and morphine are two strong and effective pain relievers for severe pain, fentanyl is stronger and more potent.

What Is Fentanyl? 

Fentanyl is a strong synthetic opioid, meaning it is created in a lab. It is designed to treat severe pain, though it can also produce an addictive high when misused. 

In the past decade, there has been an increase in fentanyl abuse. Many illegal labs produce fentanyl and mix it into other drugs to make the effects more extreme. 

Unfortunately, most users are unaware of the presence of fentanyl and thus the potency of the drug they are consuming. An increase in fatal drug overdoses throughout the U.S. has been linked to fentanyl. 

Common street names for fentanyl include the following: 

  • Tango and Cash
  • Great Bear
  • Apache 
  • China Town
  • Murder 8
  • Dance Fever
  • Friend
  • He-Man
  • Jackpot
  • China Girl
  • Goodfellas
  • King Ivory

As a medication, fentanyl is prescribed to treat severe pain, such as that following surgery. It can also be prescribed to individuals with chronic pain who have become tolerant to less potent opioids. 

In its medical form, fentanyl is prescribed as a shot, patch, or as a lozenge similar to a cough drop. Illegally, fentanyl is sold as a powder, on blotter paper, used as eye drops or in nasal sprays, and as pills designed to appear like legal prescription opioids. 

What Is Morphine? 

Morphine is a non-synthetic narcotic drug prescribed for the treatment of pain. Morphine is derived from the opium poppy and can be used directly or processed into other pain relievers, like codeine. It can be taken as an oral solution, tablet, capsule, or injectable solution. 

Common street names for morphine include the following: 

  • Unkie 
  • Emsel
  • Dreamer 
  • God’s Drug
  • Mister Blue
  • First Line
  • Hows 
  • Morpho
  • Morf 

Morphine is a Schedule II drug under the Controlled Substances Act, meaning it has a legally recognized medical use. However, it is also frequently misused due to the physical pain relief it can offer as well as its euphoric effects on the mind. People dependent on or addicted to morphine often inject it, as it enters the bloodstream, and the high effects are experienced very quickly. 

Similarities Between the Drugs

Morphine and fentanyl are similarly used and misused drugs. Both drugs can be legally prescribed for pain relief in appropriate situations, and both are abused for recreational purposes. 

Morphine and fentanyl cause similar effects and pose similar risks. Similarities between the drugs, as described by the Drug Enforcement Administration (DEA) include the following:

  • They are both legally prescribed painkillers. 
  • They both pose a high risk of addiction. 
  • It is possible to overdose on both.
  • Both drugs can be taken as lozenges, sprays, tablets, patches, and injections. 
  • They produce similar effects, including euphoria, relaxation, pain relief, confusion, drowsiness and sedation, dizziness, nausea and vomiting, urinary retention, constricted pupils, and depressed respiration.

Additionally, once dependent on either drug, unpleasant withdrawal symptoms are likely to occur when use stops. Common opioid withdrawal symptoms include agitation, anxiety, muscle aches and pains, tearing and runny nose, sweating and chills, nausea, vomiting, and diarrhea. Without medical intervention, severe withdrawal symptoms can be life-threatening. 

Key Differences Between Fentanyl & Morphine

One of the fundamental differences between fentanyl and morphine is how they are produced. Fentanyl is synthesized in labs, both legally and illegally, while morphine is a natural opioid derived from the poppy plant, explains the DEA. Fentanyl is also an estimated 100 times stronger than morphine, making it a far more dangerous drug. 

Illegally, fentanyl is commonly sold in combination with heroin and other drugs. Just a small dose of fentanyl can cause a fatal overdose, especially when combined with other substances. The recent rise in fentanyl use has fueled the ongoing opioid overdose epidemic in the country. 

These are other variables between fentanyl and morphine:

Addiction Potential 

Both fentanyl and morphine have a high potential for addiction. They are effective painkillers to which the body can quickly develop a tolerance. 

Even when used as prescribed by a doctor, physical dependence on fentanyl or morphine can occur. As it is so potent, the addiction potential to fentanyl is somewhat greater than to morphine, though both drugs must be used with caution. 

Opioid use disorder, which can develop after taking legally prescribed and illicitly obtained opioids, has been declared a public health emergency in the United States. Uncontrolled use of opioids, or an inability to stop using them despite negative consequences, risky behaviors of use, and the occurrence of withdrawal symptoms when use is suddenly stopped indicates an opioid use disorder. 

Fortunately, medical and psychological interventions are available to help treat and manage addiction to opioids like fentanyl and morphine. When people are addicted to morphine or fentanyl, medication-assisted treatment (MAT), which combines the use of medications and therapy, is generally the recommended course of care.


Due to its potency, fentanyl may be more effective at treating acute severe pain than morphine. 

A 2019 study comparing the effectiveness of morphine to fentanyl found that fentanyl produced a significant decrease in pain five minutes after providing it to patients with acute traumatic limb injuries. However, 10, 30, and 60 minutes after receiving either fentanyl or morphine, patients reported an equal reduction in pain. 

A 2017 study also found that intravenous morphine and intravenous fentanyl were equally effective in treating postoperative pain in patients just after surgery. Likewise, there were no significant differences in the side effects caused by each painkiller. 

Which Is the Right Choice to Manage Pain?

For someone who has developed a tolerance to morphine because they have been taking it to treat chronic pain, fentanyl may be necessary. Fentanyl should be taken with caution though, as the risk of addiction and the associated health consequences is high.

Your doctor will determine whether morphine or fentanyl is needed to manage pain, but their use is generally only recommended short term due to their high potential for abuse.

Updated May 10, 2024
  1. Comparison Between Intravenous Morphine Versus Fentanyl in Acute Pain Relief in Drug Abuser With Acute Limb Traumatic Injury. (2019). World Journal of Emergency Medicine.
  2. Comparison of the Effectiveness of Fentanyl Versus Morphine for Severe Postoperative Pain Management: A Randomized, Double Blind, Clinical Trial. (April 2017). Colombian Journal of Anesthesiology.
  3. Fentanyl DrugFacts. (June 2021). National Institute on Drug Abuse.
  4. Fentanyl Drug Fact Sheet. (October 2022). Drug Enforcement Administration.
  5. Morphine. (April 2020). Drug Enforcement Administration.
  6. Opiate and Opioid Withdrawal. (April 2022). National Library of Medicine.
  7. Opioid Use Disorder. Johns Hopkins Medicine.
  8. Synthetic Opioids. (April 2020). Drug Enforcement Administration.
  9. Morphine Versus Fentanyl for Pain Due to Traumatic Injury in the Emergency Department. (January/March 2013). Journal of Trauma Nursing.
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