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Carfentanil Detox Guide: Symptoms, Timeline, and Effects

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Carfentanil, one of the strongest opioid drugs on the market, is an even more potent chemical analogue of another synthetic opioid painkiller—fentanyl. It is marketed under the brand name Wildnil as a veterinary anesthetic for larger animals, such as elephants.1 Carfentanil is about 10,000 times stronger than the prescription opioid, morphine, and 100 times more potent than fentanyl.1,2 Because of its potency, this synthetic opioid poses a serious risk of overdose for humans.2 Illicit carfentanil is often encountered as a white powder that resembles heroin or cocaine. Drug dealers may add it to heroin to increase heroin’s potency.2

Like many other synthetic opioids, carfentanil is abused because of its euphoric high.3 Regular use can lead to the development of dependence and, eventually, opioid addiction. Because of the potential for significant physical dependence and the resulting extremely uncomfortable withdrawal syndrome, opioid users may find it very hard to stop without professional help.4

Carfentanil Detox Signs and Symptoms

Chronic carfentanil abuse can lead to dependence, which is the body’s natural adaptation to the presence of the opioid. Once someone has grown accustomed to a certain amount of carfentanil, suddenly quitting or reducing use can lead to the emergence of withdrawal symptoms. Carfentanil withdrawal symptoms vary in duration, time of onset, and severity, depending on the purity of the substance, the dose, frequency of use, duration of use, and method of administration. Some of the symptoms of opioid withdrawal are quite the opposite of the acute effects experienced during intoxication.5 

Carfentanil withdrawal symptoms include:4,5

  • Nausea or vomiting.
  • Diarrhea.
  • Increased sensitivity to pain.
  • Muscle aches.
  • Excessive yawning.
  • Runny nose and tearing eyes.
  • Profound sweating.
  • Fever.
  • “Goose bumps.”
  • Anxiety.
  • Irritability.
  • Depressed mood.
  • Insomnia.
  • Increased pulse and blood pressure.
  • Heightened reflexes.

As stated before, the manifestation of withdrawal symptoms varies from person to person, and the timeline may depend on a number of different factors, such as individual health difference and any concurrent consumption of alcohol or other drugs.

Withdrawal Timeline

The timing of the onset of opioid withdrawal symptoms depends on several elements, including the type of opioid, route of administration, average dose taken, and half-life of the drug. It may also be influenced by an individual user’s physical and mental health status. On average, opioid withdrawal symptoms can emerge anywhere from 6 hours after last dose to 4 days later. In the case of short-acting opioids like carfentanil, withdrawal symptoms may be seen 6–12 hours after the last dose.4

Some symptoms can persist for weeks or even months even after acute withdrawal has resolved. These lasting withdrawal symptoms may include:4

  • Depression.
  • Anxiety.
  • Insomnia.
  • Anhedonia, or a loss of interest in normal activities.

 As with other types of opioid withdrawal, carfentanil detox is seldom immediately dangerous, but there are a number of complications that could occur throughout the process.

Detox Complications

Carfentanil and other opioid withdrawal symptoms can be very uncomfortable. Although usually not life-threatening, these symptoms can make it difficult to quit without detox or treatment.7

Some of the common withdrawal complications include:5

  • Dehydration and electrolyte imbalance: The frequent vomiting and diarrhea associated with withdrawal can leave a person fluid depleted and with serum electrolyte disturbances.
  • Worsening of underlying heart issues: Pre-existing heart problems can be exacerbated during opioid withdrawal because of the increased blood pressure and pulse rate that may accompany withdrawal.
  • Anxiety disorders: Users with anxiety disorders often experience a worsening of anxiety-related symptoms and panic attacks during withdrawal.
  • Increased pain: People who have chronic pain conditions can experience increased pain during withdrawal due to a reduced pain threshold.

Formal detox treatment can help ease the symptoms of opioid withdrawal significantly and reduce the risk of relapse.

Formal Detox Treatment

The Substance Abuse and Mental Health Services Administration (SAMHSA) recommends 24-hour detoxification services for opioid withdrawal as it can prevent unnecessary patient suffering.5 Detox is the healthy way for carfentanil and other opioid users to quit. There are many different settings in which detox treatment can take place, including:

  • Physician’s office: Patients with mild to moderate withdrawal symptoms may be able to undergo detox treatment via their primary care physician or a physician’s office, but it is not often the most beneficial setting for someone with a history of significantly severe opioid abuse.
  • Outpatient clinic: Outpatient treatment may be provided in an ambulatory care center or other clinical setting. An outpatient detox protocol will be prescribed by trained clinicians who will provide medically supervised assessment, administer any detoxification medications, and help make arrangements for aftercare or referral services. The sessions are usually provided on a regular schedule. This level of care is most appropriate for patients with good social support at home.
  • Hospital: Some patients may visit hospitals or emergency rooms for initial withdrawal treatment or in the event of a medical emergency, such as an overdose. Although emergency rooms can provide assessment and acute medical or psychiatric care, they do not provide longer-term opioid stabilization or maintenance, which will require regular dosing and eventual tapering of opioid detox medications. Therefore, they usually refer patients to inpatient detox facilities once the acute issues have been successfully managed.
  • Inpatient detox: These treatment centers provide 24-hour supervision and medical detox. They are equipped to administer medical care and may utilize physicians, nurses, and psychiatric staff to manage any complications of acute intoxication and withdrawal.

Carfentanil detox may include the following medications or treatments, depending upon the user’s withdrawal manifestation:5

  • Medically supervised, 24-hour observation: This can help treatment staff monitor for and attend to any dangerous complications stemming from pre-existing conditions.
  • Methadone maintenance: Methadone is a full opioid agonist medication used to reduce cravings and alleviate opioid withdrawal symptoms.
  • Clonidine: Research has proven that this medication is highly effective for treating some of the withdrawal symptoms of opioid withdrawal, but is often used in conjunction with other medications.
  • Buprenorphine: This is a partial opioid agonist medication commonly used to manage opioid withdrawal symptoms and ease cravings.
  • Oral or intravenous fluids: This is used to treat dehydration or electrolyte imbalances.

Detoxification is the first step to treating carfentanil dependence or addiction. Because acute opioid withdrawal is followed by a longer period of withdrawal that can last for months or even years and include symptoms like depression, anxiety, strong cravings for opioids, and insomnia, and relapse is a common part of recovery, it is essential that patients receive follow-up substance abuse treatment. A professional addiction treatment program can equip a patient with the skills needed to avoid relapse, make healthier choices, and remain clean and sober.


  1. U.S. Library of Medicine: National Center for Biotechnology Information. (2017). CARFENTANIL.
  2. Drug Enforcement Administration. (2017). FIVE QUICK FACTS: CARFENTANIL.
  3. NIDA. (2017). Opioids.
  4. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Publishing.
  5. SAMHSA. (2015). Detoxification and Substance Abuse Treatment: A Treatment
    Improvement Protocol TIP 45.
  6. National Institute on Drug Abuse. (2017). Emerging Trends and Alerts.
  7. World Health Organization: Western Pacific Region. (2009). Clinical guidelines for withdrawal management and treatment of drug dependence in closed

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