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Updated on February 14, 2022

How Long Does Fentanyl Stay in Your System?

What is Fentanyl?

Fentanyl, also known as lonsys, subsys, and duragesic, is a pain-relieving narcotic. Fentanyl is 50 to 100 times stronger than morphine. 

Prescription drugs similar to Fentanyl include oxycodone, codeine, and hydrocodone. 

How Long Does It Take to Feel Fentanyl’s Effects?

Fentanyl is used for opioid-tolerant pain patients as a lozenge tablet or a transdermal patch. The latter is sometimes sold under the brand name Duragesic.

The acute effects of fentanyl may include: 7

  • Dizziness
  • Drowsiness
  • Euphoria
  • Nausea
  • Pain relief

The lozenge tablet delivers effects quickly. With the patch, it can take a few hours to start experiencing the results. Do not apply additional patches if you feel it is not effective immediately.

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How Does Fentanyl Work?

Fentanyl attaches to and activates specific opioid receptors. These receptors are located in parts of the brain that affect pain and emotion.

Fentanyl also boosts dopamine release from particular nerve cells in our brain’s reward center through its interaction with these receptors.

This increased dopamine activity links with a reinforcing sense of euphoria. However, fentanyl can also reduce breathing. Considering fentanyl’s potency, this significantly increases the risk of overdose.8

Side Effects of Fentanyl & Overdose Risks

Fentanyl is a schedule 2 prescription drug with several serious side effects. Here are the most common:

  • Respiratory depression
  • Drowsiness 
  • Nausea 
  • Sluggishness 
  • Confusion 
  • Distorted senses
  • Constipation 
  • Substance use dependency 
  • Overdose

An increase in fentanyl popularity is thought to be a driving force of the opioid epidemic. Almost 30% of opioid prescriptions are abused. Fentanyl abuse is heavily linked to future heroin abuse. 80% of people that abuse fentanyl goes on to build heroin dependency.

Fentanyl is highly addictive and highly potent. This combination increases the risk of a fentanyl overdose. In some parts of the United States, fentanyl overdoses increased 500% in one year. Fentanyl overdoses are often treated with naloxone, which reverses the opioid’s effects. 

Fentanyl, despite its illicit drug use, also has medicinal properties. Transdermal patches of fentanyl are often prescribed to treat isolated severe pain (i.e., back pain, knee pain, etc.).

A fentanyl patch is often abused for the fentanyl within the patch. Once extracted, the fentanyl may be taken orally, nasally, or intravenously. 

Fentanyl can also be created in illegal labs. The Fentanyl made in illicit labs differs significantly from medical Fentanyl. Fentanyl produced of unlawful drug use is often mixed or “cut” with synthetic opioids. The additional substances, unmonitored fentanyl potency, and excessive use of street-grade fentanyl contribute to countless overdoses and dependencies.

Street-grade fentanyl can also have varying responses to naloxone due to the addition of other substances.

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What Happens if You Overdose on Fentanyl?

Fentanyl’s potency makes overdose a risk, especially if the individual using it thinks it is another drug.8 Combining substances like alcohol and benzodiazepines (Xanax, Valium, Klonopin) with fentanyl also boosts the risk of overdose and death by respiratory arrest.

The following are signs and symptoms of Fentanyl overdose:9

  • Severely slowed or stopped breathing
  • Blue lips and skin color
  • Cold, clammy skin
  • Constricted pupils
  • Stupor
  • Seizures
  • Loss of consciousness
  • Coma

How Long Does Fentanyl Stay in Your System (Drug Test Detection Time)?

The amount of time fentanyl stays in your system varies based on several individualized factors. Factors include body fat, age, gender, diet, genetics, and more. 

Urine Test 

This drug test detects fentanyl in urine within 24 hours of the last use. Fentanyl remains detectable in the body for up to 72 hours from last use. 

Saliva Test 

Fentanyl drug use can’t be consistently detected by drug testing. Fentanyl, even when taken orally, goes through extensive bodily filtering. This process leaves behind undetectable traces of Fentanyl and its metabolites. 

Blood Test 

Blood drug tests detect fentanyl for up to 72 hours from last use. 

Hair Test

Hair drug tests are often used to establish a brief history of fentanyl use.

Fentanyl isn’t detectable in hair for the first few days after the last use. However, once fentanyl is in the hair, it can be detected for up to 3 months. Hair drug tests are often used in tandem with positive urine or blood tests to reveal substance abuse patterns.

Drug screenings are designed to detect fentanyl and its metabolites norfentanyl and desropionylfentanyl.

Repeated fentanyl drug abuse increases the level of these metabolites. This increase makes positive fentanyl drug tests more likely. 

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What is The Half-Life of Fentanyl? 

The half-life of fentanyl varies with each route of administration. Intravenous (IV) fentanyl has a half-life of approx 8 hours. This is the most common route of fentanyl when administered in a hospital setting. 

When taken orally, fentanyl has a half-life of approx 20 hours. Although rarer, fentanyl may be administered orally for some surgeries. The time differences for the half-lives are due to the bioavailability of the drug.

Bioavailability is defined by how much of a compound (substances, food, medicine, etc.) can be effectively absorbed by the body.

IV fentanyl has a much higher level of bioavailability than other routes of administration. This also means the body absorbs the substance quicker. Conversely, oral administration of fentanyl has much lower bioavailability. 

This means it takes longer for the body to absorb the fentanyl and, to a degree, limits how much fentanyl is in the body at one time. Simply put, only a small amount of fentanyl remains in saliva. Because of this, saliva drug tests are ineffective at detecting fentanyl.

How Long Do The Effects of Fentanyl Last?

The amount of time a fentanyl high lasts varies based on individual health factors and by route of administration.

  • IV Fentanyl — the effects of IV fentanyl can be felt immediately and persist for up to 4 hours. IV Fentanyl is the most common method of administration in a healthcare setting.
  • Oral Fentanyl — the effects of orally delivered fentanyl can take up to 30 minutes to become apparent. The intensity of the high and duration of it will also vary if the individual allows the drug to be absorbed through the gums or if they swallow the drug whole. On average, fentanyl highs last longer if swallowed due to bioavailability, but it has intenser effects when taken intravenously. 
  • Nasal Fentanyl — When ingested nasally, fentanyl peaks around the 60-minute mark. 

Long-term fentanyl use has its side effects and dangers. These long-term dangers are prevalent among individuals with drug abuse issues. However, the long-term effects are also found in individuals prescribed Fentanyl for chronic pain.

Medical professionals will weigh the long-term dangers of fentanyl use against the level and consistency of the pain it's prescribed to treat. 

Long-term fentanyl effects include:

  • Gastrointestinal Inflammation — gastrointestinal inflammation is caused by chronic constipation caused by everyday fentanyl use. This inflammation can cause internal bleeding.
  • Sleep Apnea — sleep apnea is caused by the severe respiratory depression brought on by daily fentanyl use. Sleep apnea can induce several illnesses such as high blood pressure, increased heart rate, narcolepsy, and mood disorders.
  • Weakened Immune System — fentanyl is an immunosuppressant. Continuous fentanyl use can lead to an impaired immune system. This makes the body more susceptible to health problems. 

These are just a few of the potential hazards of long-term fentanyl use. In many cases, addiction therapies are needed to assist in recovery.

Treatment Options for Opioid Abuse & Addiction

There are several options for people suffering from opioid addiction. These include:

Medication-Assisted Therapy (MAT)

There are three medications approved to treat opioid use disorder: buprenorphine, methadone, and naltrexone. These medications are used only with medical supervision.

Buprenorphine and methadone can help you manage withdrawal symptoms throughout the detoxification process. Because of this, a person experiences reduced cravings for opioids, thereby restoring balance in the brain circuits.

Naltrexone is less commonly used, but it blocks your opioid receptors, making it impossible to get high. Medication-assisted therapy is most effective when combined with other forms of treatment.

Inpatient Programs

Inpatient programs are the most intensive and effective treatment options for opioid addiction.

These programs guide you through medically supervised detoxification, then behavioral therapy and other services (possibly including MAT), will be added to your treatment.

They typically last 30, 60, or 90 days. However, they may be longer if necessary.

Partial Hospitalization Programs (PHPs)

PHPs are also known as intensive outpatient programs (IOPs). They are the next most intensive type of treatment for opioid addiction.

They provide similar services to inpatient programs such as detoxification, behavioral therapy medical services, and custom treatments such as MAT.

The difference is that in a PHP, the patient returns home to sleep. Some programs will include transportation and meals, but this varies by program.

Partial hospitalization programs are helpful for both new patients and patients who have completed inpatient treatment and still need intensive recovery therapy.

Outpatient Programs

Outpatient programs work best for people who have a high level of motivation to recover. They create treatment programs that work around your schedule.

These programs can either be an effective treatment option for new patients or a part of an aftercare program for people who complete inpatient or partial hospitalization programs.

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  1. Baldini, Angee, et al. “A Review of Potential Adverse Effects of Long-Term Opioid Therapy: A Practitioner's Guide.” The Primary Care Companion for CNS Disorders, Physicians Postgraduate Press, Inc., 2012
  2. Lee, Jaewon, et al. “Clinical Usefulness of Long-Term Application of Fentanyl Matrix in Chronic Non-Cancer Pain: Improvement of Pain and Physical and Emotional Functions.” Clinics in Orthopedic Surgery, The Korean Orthopaedic Association, Dec. 2016
  3. Peng, Philip W. H., and Alan N. Sandler. “A Review of the Use of Fentanyl Analgesia in the Management of Acute Pain in Adults .” Anesthesiology, American Society of Anesthesiologists, 1 Feb. 1999
  4. Schifano, Fabrizio, et al. “Assessing the 2004-2018 Fentanyl Misusing Issues Reported to an International Range of Adverse Reporting Systems.” Frontiers in Pharmacology, Frontiers Media S.A., 1 Feb. 2019
  5. Schwartz, J G, et al. “Measurements of Fentanyl and Sufentanil in Blood and Urine after Surgical Application. Implication in Detection of Abuse.” National Library of Medicine, 1994
  6. Silverstein, Jeffrey, et al. “An Analysis of the Duration of Fentanyl and Its Metabolites ... : Anesthesia & Analgesia.” LWW, 1993
  7. Drug Testing, MedlinePlus, July 2020
  8. Fentanyl, MedlinePlus, June 2021
  9. Drug Enforcement Administration, Drugs of Abuse, 2017

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