What Is Fentanyl and How Does It Work?
Medication Safety Notice: This content is for educational purposes only and does not replace medical advice. Fentanyl is a high-risk opioid. Do not start, stop, or change opioid use without medical supervision. If an overdose is suspected, call 911 immediately.
Fentanyl is a synthetic opioid that is up to 100 times stronger than morphine and up to 50 times stronger than heroin.[1] In regulated medical settings, fentanyl may be prescribed to manage severe pain, such as pain following major surgery or pain related to advanced cancer. In hospitals, it is often administered via injection, allowing it to reach the brain within seconds.
Fentanyl is classified as a full opioid agonist, meaning it binds directly to opioid receptors in the brain. This action reduces pain but also activates the brain’s reward system. At higher doses, fentanyl can produce intense euphoria, which significantly increases the risk of misuse, dependence, and overdose.
Common pharmaceutical forms of fentanyl include Duragesic® (transdermal patch), Actiq® (oral lozenge), and Sublimaze® (injectable). Outside of medical settings, illicit fentanyl is far more dangerous. It is often mixed into other drugs without a person’s knowledge and may contain toxic substances not meant for human consumption.
Because fentanyl is extremely potent, some individuals develop dependence rapidly, sometimes after only limited exposure. Others may begin using fentanyl for legitimate pain relief and later find they cannot function normally without it. When fentanyl use is reduced or stopped, withdrawal symptoms can be severe and overwhelming.
If you are concerned about a family member’s opioid use, it may help to review common signs families miss when a loved one is using fentanyl.
What Are Fentanyl Withdrawal Symptoms?
Fentanyl withdrawal occurs when the body, which has adapted to the presence of the drug, is forced to function without it. Symptoms can be both physically and psychologically distressing and may escalate quickly without medical support.
Physical Withdrawal Symptoms
- Body aches and muscle pain, often described as flu-like symptoms
- Sweating and chills
- Nausea and vomiting
- Diarrhea, which can lead to dehydration and electrolyte imbalances
- Abdominal cramping
- Rapid heartbeat and palpitations
- Increased blood pressure
- Dilated pupils
- Goosebumps (piloerection)
- Insomnia or disrupted sleep
- Extreme fatigue and weakness
Because these symptoms can strain the heart and other vital systems, fentanyl detox should be done under medical supervision to reduce the risk of serious or fatal complications.
Psychological Withdrawal Symptoms
- Anxiety and restlessness
- Irritability and mood swings
- Depression and feelings of hopelessness
- Agitation
- Intense fentanyl cravings
- Difficulty concentrating
- Heightened sensitivity to light, sound, or touch
- Changes in appetite
- Lack of motivation or emotional numbness
- Emotional instability
Behavioral Withdrawal Symptoms
- Social withdrawal and isolation
- Loss of interest in previously enjoyable activities
- Impaired judgment and decision-making
- Risky behaviors to obtain fentanyl or other opioids
- Financial strain related to substance use
- Neglecting responsibilities at work, school, or home
- Relationship conflict
- Secretive behavior or dishonesty about drug use
Withdrawal symptoms may vary in intensity depending on dosage, frequency of use, and how long fentanyl has been used. For comparison, withdrawal experiences from other opioids, such as tramadol, are discussed here: Tramadol withdrawal symptoms.
Should You Stop Taking Fentanyl Cold Turkey?
Stopping fentanyl abruptly, often referred to as going “cold turkey,” can be extremely dangerous. Severe withdrawal symptoms can place intense stress on the body and may increase the risk of relapse, overdose, or death.
For many people, the safest first step is medically supervised withdrawal support, followed by structured treatment based on symptom severity, safety needs, and home supports. Options may include a day program with medical monitoring, or step-down outpatient care as stability improves.
Many people attempt to detox on their own, believing they can manage withdrawal symptoms without help. This approach significantly increases risk. Medical detox provides monitoring, symptom management, and support that can reduce complications and improve safety.
How Long Do Fentanyl Withdrawal Symptoms Last?
Withdrawal symptoms typically begin between 8 and 48 hours after the last dose. Acute symptoms may last up to 20 days, although some psychological symptoms and cravings can persist longer.[2]
Because fentanyl remains in the body for varying lengths of time depending on dosage and metabolism, understanding how long it stays active can help explain withdrawal timing. Learn more here: How long does fentanyl stay in your system?
Can You Overdose on Fentanyl?
When to Seek Emergency Help
Call 911 immediately if you suspect an overdose or if someone has any of the following symptoms:
- Slow, shallow, or stopped breathing
- Blue or gray lips or fingertips
- Unable to wake up, severe confusion, or loss of consciousness
- Gurgling or choking sounds
- Pinpoint pupils
Seek urgent medical care (ER or urgent evaluation) if withdrawal symptoms become severe or unmanageable, especially if there is:
- Severe vomiting or diarrhea (risk of dehydration)
- Chest pain, fainting, or a racing heartbeat
- Suicidal thoughts, panic, or worsening mental health symptoms
If you have access to naloxone (Narcan), administer it and call 911. Stay with the person until help arrives.
Yes. Fentanyl overdose is a major public health crisis. In 2021, more than 70,000 overdose deaths in the United States involved synthetic opioids, primarily fentanyl.[3]
People experiencing withdrawal are at especially high risk for overdose. Intense cravings, reduced tolerance, and impaired judgment increase the likelihood of using a dangerous amount.
Care Options for Fentanyl Withdrawal and Recovery
There is no single “right” level of care for everyone. Treatment planning is typically based on withdrawal severity, overdose risk, co-occurring mental health symptoms, and the safety of the home environment.
- Partial Hospitalization Program (PHP): A structured day program with intensive clinical support and regular monitoring. Learn about PHP in Houston.
- Intensive Outpatient Program (IOP): A step-down option that provides strong therapeutic structure while allowing more flexibility for work, school, or family needs. Learn about IOP in Houston.
- Outpatient Program (OP): Ongoing support for recovery maintenance, relapse prevention, and mental health stabilization. Learn about outpatient care in Houston.
- Individualized Intensive Program (IIP): A tailored approach that integrates clinical care with structure and support based on individual needs. Learn about IIP in Houston.
If you are unsure what level of care is appropriate, you can contact our team to discuss options and next steps.
If you are supporting a loved one and don’t know what to do next, our Family Support resources can help you understand options and how to respond safely.
