fentanyl detox | renaissance recovery
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By: Renaissance Recovery

Clinically Reviewed by: Diana Vo, LMFT

Last Updated:


Authored By: Joe Gilmore

Table of Contents

Fentanyl is a synthetic opioid 100 times stronger than morphine, although the fentanyl detox unfolds similarly to detox from other opioids.

Although data from NSDUH 2020 shows that the incidence of opioid use disorder is declining in the United States, synthetic opioids like fentanyl are a growing threat. Of the 92,000 drug overdose deaths reported by the CDC in 2020, 56,500 deaths involved synthetic opioids – primarily fentanyl.

Fentanyl detox takes from a few days to a few weeks from the last use of fentanyl. The following variables will all impact the duration of detoxification:

  • Amount of fentanyl in the system
  • Typical fentanyl dosage
  • Delivery method – injection or patch
  • Other substances in the system

Today’s guide will outline what to expect from fentanyl detox and how to detox from fentanyl as safely as possible.

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What Is Fentanyl Withdrawal?

Using fentanyl raises the risk of tolerance and physical dependence, as well as abuse and addiction in the form of opioid use disorder, a chronic lifelong condition.

Tolerance to opioids – especially synthetic opioids as potent as fentanyl – can develop rapidly. As tolerance grows, you’ll need more fentanyl to achieve the same effects, or you’ll need to take fentanyl more frequently.

Once you become physically dependent on opioids like fentanyl, intense withdrawal symptoms present in the absence of the substance. Withdrawal symptoms usually manifest about 12 hours after the last dose, continuing for a week or so.

According to the National Institute on Drug Abuse (NIDA), addiction is a chronic relapsing condition that involves more than physical dependence. Fentanyl addiction is defined by compulsively seeking and using the substance despite obviously adverse outcomes. Obtaining and using fentanyl becomes the main motivation and driver in life.

Fentanyl addiction can be treated in an inpatient or outpatient setting, depending on the severity of the opioid use disorder and any co-occurring mental health disorders. With fentanyl detox, though, the safest and most effective option involves a medically-supervised detox.

How Long Does It Take to Detox Fentanyl?

The first opioid withdrawal symptoms present from 8 to 48 hours after the last dose. 

The onset of fentanyl withdrawal is contingent on the frequency and quantity of dosages.

Although everyone detoxing from fentanyl has unique circumstances, most fentanyl detoxes follow a broadly similar timeline, with symptoms enduring for about a week in most cases.

Fentanyl Detox: Day 1

Just like codeine and heroin, fentanyl is a short-acting opioid. This means withdrawal symptoms typically present from 8 to 24 hours after the last dose. The extended-release form of oxycodone, by contrast, is a long-acting opioid, triggering withdrawal symptoms anywhere from 24 to 48 hours after the last dose.

On the first day of fentanyl detox, you can expect to encounter any of the following symptoms:

  • Strong cravings for fentanyl
  • Aggression
  • Anger
  • Depression
  • Irritability
  • Muscular aches and pains
  • Appetite loss
  • Headaches
  • Insomnia and disrupted sleep patterns

Fentanyl Detox: Day 2

The withdrawal symptoms above will continue over the second day of fentanyl detox, in addition to the following adverse effects:

  • Panic attacks
  • Runny nose
  • Excessive sweating
  • Upset stomach

Fentanyl Detox: Day 3

During the third day of fentanyl detox, withdrawal symptoms will peak. All short-acting opioids share this detox timeline.

In the acute phase of fentanyl withdrawal, the most serious symptoms are as follows:

  • Diarrhea
  • Vomiting
  • Nausea

You can also expect a continuation of the above withdrawal symptoms.

Fentanyl Detox: Day 4

With the acute phase of withdrawal complete, some of the following symptoms may persist:

  • Cramps
  • GI issues
  • Fatigue
  • Enlarged pupils
  • Shivering

Fentanyl Detox: Day 7

Most fentanyl withdrawal symptoms should subside after a week or so. It is common for fatigue, depression, and disrupted sleep patterns to linger for longer.

In the event of post-acute withdrawal syndrome (PAWS), some symptoms persist for several months after the last use of fentanyl, including:

  • Irritability
  • Fatigue
  • Disrupted sleep patterns
  • Strong cravings for opioids
  • Depressed mood


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What Are the Most Common Fentanyl Withdrawal Symptoms?

As outlined, although fentanyl detox usually lasts for around a week, some people will detox in more or less time. The most effective fentanyl detox hinges on a comprehensive evaluation. This evaluation can determine the likely duration of detox for you.

Even if you take opioids exactly as prescribed, long-term use causes tolerance to build. As your body becomes desensitized to the rewarding and pain-relieving properties of opioids, you’ll be forced to increase the frequency or amount of fentanyl doses to achieve the same effects.

The sustained abuse of opioids leads to functional changes in nerve receptors in the brain. As the nerve receptors become opioid-dependent, the altered brain chemistry triggers the presentation of withdrawal symptoms when opioids are no longer in the system.

All opioids, from fentanyl and heroin through to prescription painkillers, cause the following standard withdrawal symptoms:

  • Diarrhea
  • Nausea
  • Vomiting
  • Insomnia
  • Anxiety
  • Raised blood pressure
  • Sweating
  • Chills
  • Increased body temperature
  • Bone pain
  • Muscle pain
  • Racing heart

Although neither opioid or opiate withdrawal is associated with psychosis, some people detoxing from fentanyl will experience delusions, hallucinations, or other symptoms of psychosis.

Now you know what to expect, how to detox off fentanyl?

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How to Detox from Fentanyl

To mitigate the unpleasant withdrawal symptoms and to prevent the onset of psychotic symptoms, you should seek medical assistance before you stop using fentanyl. The safest, most comfortable, and most effective approach to fentanyl detox involves a medically-supervised detox.

Some people undertake fentanyl detox in an inpatient rehab before transitioning directly into ongoing inpatient treatment. For those who intend to engage with outpatient treatment for fentanyl addiction, it is advisable to first attend a medical detox center for a clinical detox before commencing outpatient therapy.

During the fentanyl detox process, all toxins and toxic metabolites will be purged from the system.

Whether detox takes place in a standalone capacity in a licensed medical detox center or as the precursor to inpatient treatment at a residential rehab, a supervised detox provides continuous emotional and clinical care. A treatment team will monitor for complications during withdrawal.

Medication-assisted treatment can help to alleviate many of the most intense symptoms of fentanyl withdrawal. Several FDA-approved medications can also help to reduce cravings for fentanyl.

As you transition from fentanyl detox into ongoing treatment for fentanyl addiction, you may continue with medication-assisted treatment to promote abstinence.

MAT is always most effective when delivered alongside behavioral interventions. In addition to counseling, psychotherapy like cognitive behavioral therapy (CBT) can help you to identify what triggers you to use fentanyl and to replace substance use with healthier coping mechanisms.

Despite its strong potential for abuse and addiction, fentanyl addiction usually responds positively to treatment with evidence-based psychotherapies and medications.

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Joseph Gilmore has been in the addiction industry for three years with experience working for facilities all across the country. Connect with Joe on LinkedIn.