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Fentanyl Side Effects

Fentanyl is a powerful opioid that can cause a variety of unwelcome side effects. It is also perhaps the deadliest drug in our modern world in terms of the number of overdose deaths it contributes to annually. 

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Key Facts

  • Fentanyl is about 50 to 100 times stronger than morphine, which is often the “standard” opioid other opioids are compared against.
  • Among overdose deaths involving opioids, fentanyl is most associated with increasing the risk of a fatal overdose.
  • Fentanyl is a synthetic opioid, meaning it is in a group of opioids that have contributed to a massive spike in opioid deaths in recent years and a key part of why the opioid epidemic has continued. The epidemic has arguably significantly worsened despite greater awareness of the dangers around opioid use.

Side Effects Associated With Fentanyl

If you see signs of a fentanyl overdose in yourself or another person, call 911 immediately.

As a powerful opioid, fentanyl is associated with a number of side effects, including these:

  • Temporary feelings of euphoria
  • Reduced respiration (respiratory depression)
  • Low blood pressure
  • Sedation
  • Constipation
  • Dry mouth

Opioid use is also associated with the following:

  • Nausea
  • Vomiting
  • Dizziness
  • Itchy skin

Repeated use of opioids can trigger physical dependence, causing a person to go through withdrawal if they suddenly stop taking opioids. Physical dependence often goes hand in hand with addiction, making it very difficult for a person to stop misusing opioids.

Heavy opioid use, especially when mixed with other drugs, can cause a potentially fatal overdose. 

How to Tell if Someone Is on Fentanyl

Depending on how often and the amount of fentanyl a person uses, it isn’t always obvious if they’re high or not. However, a person high on opioids, especially a powerful opioid like fentanyl, will often be very sedated, euphoric despite no clear reason they would be, and may have trouble thinking clearly or focusing on important tasks.

Many people who repeatedly engage in fentanyl and/or other types of opioid use develop opioid use disorder (OUD). Often just called opioid addiction, OUD is characterized by the compulsive use of opioids even if they’re having a clearly negative effect on a person’s health and quality of life. When not using opioids, the person may have strong cravings to use more opioids and will likely be experiencing some level of withdrawal.

Risk Factors for Long-Term Fentanyl Use

Fentanyl is a powerful opioid that triggers significant brain changes with each dose. Anyone who uses the drug repeatedly could struggle to quit, but researchers have identified some factors that raise the risk of long-term use.

Those risk factors include the following:

  • A personal or family history of substance misuse
  • Untreated mental illnesses
  • Starting drugs at a younger age
  • Living in an environment that encourages drug use
  • Stress
  • Difficult childhood experiences
  • Thrill-seeking behavior

Having these risk factors doesn’t automatically mean an addiction will appear. However, someone with many of these characteristics should avoid opioids like fentanyl.

Fentanyl Withdrawal

Opioid withdrawal is often described as “flu-like” and is characterized by symptoms such as these:

  • Nausea
  • Vomiting
  • Diarrhea
  • Heavy sweating
  • Drug cravings
  • Muscle aches and cramping
  • Insomnia
  • Chills

These symptoms are temporary and not generally life-threatening, although they can cause significant discomfort. The biggest risk of opioid withdrawal is generally related to the potential for overdose if relapse occurs. Many people relapse during withdrawal in an effort to make the discomfort go away.

Many fentanyl withdrawal symptoms also greatly increase a person’s rate of fluid loss, and it is important to stay hydrated to avoid symptoms related to dehydration.

Can You Overdose on Fentanyl?

Of all opioids, fentanyl is the one that seems to statistically cause the most overdose deaths, and it also causes the most overdose deaths of any drug. Fentanyl’s greatest danger is its effect on a person’s respiration. 

Like all opioids, fentanyl can weaken a person’s breathing. It can actually weaken it so much that a person cannot physically draw in enough oxygen to support their brain’s needs. This can be life-threatening, potentially causing a person to go comatose, suffer permanent brain damage, and even die. 

Identifying an Overdose

Some common signs of a fentanyl overdose include the following:

  • Pinpoint pupils
  • Difficulty breathing
  • Very shallow breathing
  • Trouble responding or loss of consciousness
  • Clammy skin
  • Bluing skin, especially around the lips and fingertips

If you see signs of a fentanyl overdose in yourself or another person, call 911 immediately. Call even if you’re not immediately certain if it is definitely an overdose. The faster a person can get help, the more likely it is that permanent brain damage can be avoided. 

Administer naloxone (Narcan) if it is available. This drug can counteract the effects of opioids and reverse opioid overdoses. Medical attention is still needed even if naloxone temporarily reverses the overdose.

If a person’s heart has stopped or slowed dangerously, administer CPR. The 911 emergency operator can guide you through this process.

If an opioid overdose occurs, it’s a clear sign that fentanyl addiction treatment is needed. Reach out for help as soon as possible following the overdose to ensure another doesn’t occur. Addiction treatment professionals can help you or your loved one develop coping mechanisms, so opioid misuse stops and relapse is less likely.

Long-Term Health Consequences of Fentanyl Use

Overdose is the best-known consequence of fentanyl use. The drug is up to 100 times more potent than morphine, and it’s often found in street drugs. People who think they’re taking something else (like ecstasy) could take fentanyl instead, and that tainted drug could cause death.

It’s clear that people who keep taking opioids like fentanyl over long periods can face a variety of other health problems.

Researchers say long-term opioid use can lead to reduced fertility, cardiovascular disease, and poisoning. Pregnant women who take opioids can also subject their babies to the drug, causing neonatal health problems or miscarriage.

Studies also suggest that people who take opioids for long periods experience poor brain health. Their symptoms can include the following:

  • Memory loss
  • Lack of attention
  • Poor special planning
  • Slow information processing
  • Reduced problem-solving ability
  • Impulsivity

Fentanyl can also cause extreme, everyday stress and distress. One man who has used fentanyl for long periods told a reporter that he lost his home and was forced to live on the streets. He said he thought fentanyl helped him deal with homelessness, but he also told the reporter: “I don’t think I’ll ever be the same.” He must keep using every few hours to avoid withdrawal, leaving him little time to get his life back on track.

Mental Health & Fentanyl Use

Researchers say that close to 19% of people with mental health disorders use prescription painkillers like oxycodone and fentanyl. Sometimes, the mental health issue arrives before the opioid abuse starts. However, ongoing opioid abuse can cause mental health problems too.

Long-term opioid abuse is associated with mental health issues like the following:

  • Depression
  • Post-traumatic stress disorder
  • Personality disorder
  • Suicide attempts

More than half of all people who abuse opioids like fentanyl meet the criteria for a mental health disorder.

Opioids cause persistent brain chemical changes, including dopamine reductions. These alterations can cloud your thinking and depress your mood, making continued drug use both more likely and more dangerous.

Integrated treatment programs address both fentanyl addiction and mental illness simultaneously. Medications like buprenorphine and methadone can lessen chemical imbalances caused by addiction. Behavioral therapies like cognitive behavioral therapy can help people to modify thought patterns and reactions. Anyone with addiction and poor mental health could benefit from these programs.

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Medically Reviewed By Dr. Alison Tarlow

Dr. Alison Tarlow is a Licensed Clinical Psychologist in the States of Florida and Pennsylvania, and a Certified Addictions Professional (CAP). She has been a practicing psychologist for over 15 years. Sh... Read More

Updated March 20, 2024
  1. Fentanyl. Drug Enforcement Administration.
  2. Opioid overdose. (August 2021). World Health Organization.
  3. Opioid Use Disorder. Johns Hopkins Medicine.
  4. Overdose Death Rates. (January 2022). National Institute on Drug Abuse.
  5. Side Effects of Opioids. Faculty of Pain Medicine of the Royal College of Anaesthetics.
  6. Trends in Opioid Use, Harms, and Treatment. Pain Management and the Opioid Epidemic: Balancing Societal and Individual Benefits and Risks of Prescription Opioid Use.
  7. Fentanyl DrugFacts. (June 2021). National Institute on Drug Abuse.
  8. Medical and Psychological Risks and Consequences of Long-Term Opioid Therapy in Women. (September 2012). Pain Medicine.
  9. Persistent and Abusive Use of Opioids: Short- and Long-Term Effects on the Brain. Brain Injury Association of America.
  10. My Fight with Fentanyl: Stories from Three People Battling Addiction. (August 2023). Los Angeles Daily News.
  11. Prescription Opioid Use Among Adults with Mental Health Disorders in the United States. (July 2017). Journal of the American Board of Family Medicine.
  12. Long-Term Opioid Use: Assessment of Mental Health Issues. (November 2020). Medicine Today.
  13. What Are the Treatments for Comorbid Substance Use Disorder and Mental Health Conditions? (April 2020). National Institute on Drug Abuse.
  14. Risk Factors for Opioid Use Disorder and Overdose. (November 2017). Anesthesia and Analgesia.
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