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Medically Reviewed

What Are the Long-Term Effects of Fentanyl?

- 6 sections

Medically Verified: 2/1/24

Medical Reviewer

Chief Editor


All of the information on this page has been reviewed and verified by a certified addiction professional.

Fentanyl has become a primary cause of overdose deaths in the United States.[1] It’s now synonymous with the opioid epidemic and is responsible for enormous destruction to individuals, families and communities.

Fentanyl is an opioid that affects the same receptors in the brain and body as other prescription pain medicines and heroin but in a much more potent way.

From the short- to the long-term effects of fentanyl, it’s a highly addictive, dangerous drug.

What Is Fentanyl?

Fentanyl is a synthetic opioid medically used for the management of severe pain. It’s usually reserved in medical situations for times when other opioids aren’t effective enough at relieving pain. It reduces pain perception by binding to the spinal cord and brain receptors.

Fentanyl was developed originally in the 1960s, and estimates suggest it’s anywhere from 50 to 100 times more powerful than morphine.[2] That potency is valuable in managing severe pain, but is also why it’s so dangerous.

Different prescription formulations include lozenges, transdermal patches, injections and nasal sprays, each with a relatively rapid onset.

Outside of medical uses that are carefully supervised, fentanyl has significant risks, especially when it’s misused. Illicitly made fentanyl has been increasingly entering the illegal drug market in the United States, often being combined with other substances like cocaine or heroin.

Frequently, people take it unknowingly, or they don’t know how much they’re taking, so they consume high doses that lead to overdose and death.

How Fentanyl Works in the Brain and Body

Fentanyl binds to receptors that are part of the body’s natural pain relief system. It mostly binds to mu-opioid receptors, found in the parts of the brain regulating pain perception and the brain stem, which controls functions like breathing and heart rate. In binding to these sites, fentanyl blocks the transmission of pain signals and changes pain perception.[3]

Fentanyl also activates the brain’s reward pathways, which creates feelings of euphoria and relaxation, contributing to misuse and addiction.

When fentanyl is prescribed in medical settings, the effects on the brain and body are carefully controlled to manage pain relief without harm. Misusing fentanyl, like taking it in higher doses than prescribed, can lead to a slow down in breathing and other severe consequences.

Short-Term Side Effects of Fentanyl

In the short term, the effects of fentanyl can include:[4]

  • Pain relief.
  • Euphoria and relaxation.
  • Drowsiness and sedation.
  • Impaired cognitive and motor function.
  • Nausea and vomiting.
  • Constipation.
  • Respiratory depression, where breathing becomes slow or shallow, which can be life-threatening.

The Long-Term Effects of Fentanyl

Fentanyl’s long-term effects can depend on the dosage, duration of use, your physiology and whether you use it as prescribed or if it’s misused. In general, possible long-term fentanyl effects include:

  • Dependence and tolerance: Continued use of opioids like fentanyl can lead to tolerance. Higher doses would be needed for pain relief, and the body adapts to fentanyl’s presence. You would experience withdrawal symptoms at this point if you stopped using it as your body tried to readjust.
  • Addiction: Fentanyl has a high addiction potential, and chronic misuse can lead to compulsive-drug-seeking behaviors, continued use despite bad consequences, and a loss of control over use.
  • Withdrawal symptoms: If you discontinue fentanyl after using it over the long term, as mentioned, withdrawal symptoms may occur. These can include vomiting, muscle aches, insomnia, diarrhea and irritability. Symptoms can be severe, potentially leading to relapse without appropriate management.
  • Cognitive impairment: Prolonged fentanyl use can affect mental functions like decision-making, attention and memory. There can be changes in the brain’s structure and function over the long term.
  • Hormonal imbalance: Opioid use can disrupt the endocrine system and cause hormonal imbalances. That can then affect testosterone and estrogen, lead to sexual dysfunction and cause infertility and menstrual irregularities.
  • Respiratory issues: Long-term use increases the risk of respiratory problems, including respiratory depression, sleep-disordered breathing, and respiratory infections. This can be especially damaging in someone with pre-existing respiratory conditions.
  • Gastrointestinal problems: Using opioids can cause gastrointestinal issues like bloating and constipation, which can then lead to hemorrhoids and bowel obstruction.
  • Cardiovascular effects: Long-term opioid use can lead to heart-related problems like strokes and heart attacks. Chronic use of opioids is also associated with heart rate, blood pressure and vascular changes.[5]
  • Worse pain: Long-term opioid use can have a paradoxical effect, meaning that it can make pain sensitivity worse and lead to chronic pain conditions. This is known as opioid-induced hyperalgesia.
  • Social isolation: Fentanyl use can cause you to withdraw from social activities, relationships and hobbies as your opioid use takes up more of your time, resources and energy. This can lead to social isolation and alienation from loved ones.
  • Financial strain: The cost to get opioids paired with potential medical expenses, lost productivity and legal issues, mean that fentanyl use can affect your financial well-being.

The Development of Fentanyl Addiction

Addiction can be considered a long-term effect of fentanyl use. Addiction starts with the initial use of fentanyl, whether for prescription pain management or recreational use. From there, it interacts with the brain’s reward system, flooding it with high dopamine levels. Dopamine is associated with reward and pleasure. The high levels that come from fentanyl use reinforce drug-seeking behavior, and that then leads to a strong urge to use fentanyl again.

With continued use, your brain adapts to fentanyl’s presence, reducing its sensitivity to the drug. A person with a fentanyl addiction will have intense cravings for it and be unable to cope with their daily life without it.

As fentanyl addiction develops, a person may find no matter the consequences it creates, they’re no longer able to control their use. The urge to use fentanyl is overwhelming at this point.

Find Help for Fentanyl Addiction Today

The long-term effects of fentanyl highlight the relationship between pain relief, addiction and potential harm. From physical dependence and withdrawal symptoms to respiratory issues, the consequences of fentanyl use can be profound, and this also includes the risk of addiction.

At the Carolina Center for Recovery, we offer comprehensive, evidence-based treatment programs for fentanyl addiction. Contact our admissions team now to explore your treatment options or schedule an intake assessment.


  1. National Institute on Drug Abuse (NIDA): Drug Overdose Death Rates
  2. Centers for Disease Control and Prevention: Fentanyl
  3. National Institute on Drug Abuse (NIDA): Fentanyl DrugFacts
  4. United States Drug Enforcement Administration (DEA): Fentanyl
  5. National Institutes of Health (NIH): Opioid Impacts on Cardiovascular Health