Withdrawal | 6 min read

Fentanyl Withdrawal Symptoms & Timeline: The Fatal Risks Associated With Using This Drug

Medically Reviewed

Medically Reviewed By

Dr. Po-Chang Hsu

Dr. Po-Chang Hsu

On August 28, 2022

Written By

Amanda Stevens

Amanda Stevens, B.S.

On January 20, 2022

The Fatal Risks Associated With Using This Drug
Reading Time: 6 minutes

The current threat of illicit drugs to the very fabric of American life cannot be understated. Countless lives have been affected by this scourge already, and countless more lives hang in the balance. Not only the lives of the users but the friends and family members that care about and love them. Most people are familiar with the names of the more well-known drugs like marijuana, cocaine, heroin, and meth, but there is a relatively new chemical assassin that is hitting the streets in more and more areas, both rural and metropolitan.

This drug is called fentanyl, and it is a synthetic opioid that is about 50 times as strong as one of the top killers, heroin. It was initially developed in the ‘60s as an anesthetic that was administered intravenously, but in recent years it has found a new home with addicts and drug enthusiasts on the street due to the cheap cost and incredible potency. It is also used in limited cases on a prescription basis for individuals with chronic extreme pain that cannot be reduced or otherwise mitigated by less potent analgesics like morphine or oxycodone.

Fentanyl is so powerful in even small amounts that it is often only used in prescription cases where the individual suffering from pain has already been prescribed opioids previously and has become accustomed to them or developed a tolerance to their effects. It is not only available in pill form but is commonly administered in a transdermal patch that allows absorption through the skin over some time and lozenges that dissolve in the mouth. In rare cases, it may be prescriptively administered by injection.

How Does Fentanyl Work?

All opioids, fentanyl included, act on the central nervous system via receptors in the brain and chemically block out many pain sensations. These receptors are also responsible for releasing dopamine, a powerful neurotransmitter that signals the pleasure centers of the brain and creates feelings of euphoria and bliss. Those that are prescribed fentanyl and are not misusing the substance will generally only feel the relief of the pain the drug was prescribed to manage, while those who use fentanyl illicitly, misuse their prescription, or use the drug recreationally will generally feel the powerful euphoric feelings the opioid drug family is usually known for.

This misuse or abuse of fentanyl or fentanyl derivations is incredibly dangerous. It can not only cause a long list of potential health issues and medical conditions, but the drug can also be the cause of a possibly fatal overdose situation. While most fentanyl addicts will buy the drug knowing exactly what it is, this is something that cannot be guaranteed in some cases.

Overdose Potential

Fentanyl is becoming a common cutting agent in heroin, adding cheap bulk to the product so dealers can make more money. The problem with this is that people buying heroin often know their dose, but when part of that dose is composed of fentanyl, and they don’t know it or are unfamiliar with the effects, it can be deadly. Since the user will take much more fentanyl than their body can take, it can lead to incapacitation, respiratory depression, coma, and even death.

Signs that an overdose may be imminent or actively occurring include:

  • Labored or shallow breathing
  • Lowered heart rate
  • Low blood pressure
  • Faint pulse
  • Pupillary constriction
  • Loss of consciousness or fainting
  • Loss of mobility and speech
  • Confusion and disorientation
  • Muscle spasms
  • Hallucinations
  • Seizure

Overdose Potential

If the user can avoid all of the dangerous acute effects of the drug, they will often develop a dependency very rapidly. Once the chemical dependency is established in their system, they will experience withdrawal symptoms in as little as a few hours following their most recent dose if they do not take more. This can also lead to psychological dependence, where they consume the drug for fear of eventual or potential withdrawal symptoms.

What Do Fentanyl Withdrawal Symptoms Look Like?

Fentanyl withdrawal symptoms will generally reflect the most common opioid withdrawal symptoms. While they can vary in severity from person to person, the symptoms themselves will rarely differ by any significant margin. Once the dependency and addiction have been created, stopping the use of fentanyl or even reducing the dosage in some cases can immediately cause the withdrawal symptoms to begin. These symptoms will usually include:

  • Powerful and lasting cravings or urges to use fentanyl
  • Flu-like symptoms
  • Watering eyes
  • Runny nose
  • Increased agitation and irritability
  • Uncontrollable, excessive sweating
  • Intense and painful abdominal cramps
  • Body-wide pain in muscles and bones
  • Reduction in appetite
  • Nausea
  • Diarrhea
  • Vomiting
  • Dysphoria

In many cases, one of the most dangerous threats during the withdrawal stage is the dehydration that occurs. In some users, the dehydration can be so severe that it carries the risk of seizure, and in some individuals, these seizures can prove fatal.

Timeline of Fentanyl Withdrawal Symptoms & How They Differ Person-To-Person

The timeline of fentanyl withdrawal symptoms will vary from person to person and will depend heavily on the abuse profile of the individual and the methods they use to complete a withdrawal. Many people who attempt the withdrawal stage solo end up experiencing a long period of more intense symptoms, but the overall process can be done quicker.

When the process is attempted with medical supervision in a controlled environment, the addiction professionals will often taper down the use over time. While this can make the withdrawal process much more comfortable and successful than a solo “cold turkey” quit, it can take longer since the individual needs to be weaned off the fentanyl.

In most fentanyl users, the withdrawal stage will average about 5 to 7 days. This generally does not include the first few days following the absence of the drug, and under some circumstances, the withdrawal can go much longer. It is rare for users to experience intense withdrawal symptoms for more than 14 days in any scenario. If applicable, some users may obtain a recommendation from their healthcare provider for medically-assisted detox, which can drastically reduce withdrawal time.

Medically-assisted detox is where qualified medical professionals administer a specific type of drug, called an opioid agonist, that chemically prevents the opioids from binding with receptors and helps remove opioids from receptors they have bound to already. This forces the body to go without opioids on a very compressed time scale and can usually only be done when the user is in relatively good health aside from their addiction since it places so much stress on the body.

Commonly used drugs include buprenorphine, a partial opioid agonist, and naloxone, a complete opioid receptor block. While buprenorphine binds to receptors and relieves some withdrawal symptoms, it doesn’t produce a high or pleasurable experience for the user. Naloxone completely blocks the receptors from all opioids in the system and only activates in the presence of opioids, otherwise remaining inactive in the system.

Fentanyl Withdrawal Symptoms & How They Differ Person-To-Person

How The Withdrawal Symptoms From Fentanyl Can Point to An Underlying Addiction

Many people have been prescribed fentanyl and wonder how they can tell if they’ve developed a dependence or addiction, just as there are illicit users who think that they can control their usage and addiction but also may start to think they’ve become dependent. There are some relatively easy ways to identify if you have an underlying addiction to fentanyl. The most common is acknowledging that you begin to feel withdrawal symptoms when you aren’t using fentanyl or have reduced your dosage.

No matter how long you have been taking prescription fentanyl or using fentanyl on an illicit or illegal basis, you will be able to spot an addiction by whether withdrawal symptoms show up and, if so, how quickly and how severely they come on. Since fentanyl affects the central nervous system, the chemical changes that occur are powerful and fast-acting. In most users who have developed an addiction, these symptoms will begin to show up only hours after the most recent dose.

If you have begun to experience fentanyl withdrawal symptoms after reducing or eliminating your fentanyl consumption, you have likely developed an addiction and should seek professional help to detox safely and in relative comfort.

How To Mitigate The Withdrawal Symptoms Experienced From Fentanyl: Seeking Professional Help

If you, a family member, a friend, or anyone else you care about may have developed an addiction to fentanyl, getting help from qualified local addiction experts can be the first step to a successful and long-lasting recovery. Reach out today to talk to a professional in full confidentiality about your detox needs. By working with addiction professionals, not only can you detox in a clean and comfortable environment, but you can complete the withdrawal stage much more safely by doing it with medical supervision and help.

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Amanda Stevens


Amanda Stevens, B.S.

Amanda is a prolific medical content writer specializing in eating disorders and addiction treatment. She graduated Magna Cum Laude from Purdue University with a B.S. in Social Work. Read more

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  1. Drug Enforcement Administration. Fentanyl. Accessed August 28, 2022. https://www.dea.gov/factsheets/fentanyl