Fentanyl is up to 100 times more potent than morphine and 50 times more potent than heroin. Side effects include drowsiness, weakness, and dry mouth.

Fentanyl is an opioid pain reliever for use in medical treatment. Although healthcare professionals consider fentanyl safe and effective when a person uses it in a monitored medical setting, the drug carries a high potential for misuse, also known as abuse.

In this article, we will discuss the medical uses of fentanyl and its side effects. We will also cover misuse of fentanyl, addiction, and the risk of overdose.

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Fentanyl is a Schedule II prescription narcotic analgesic that is up to 100 times more potent than morphine and 50 times more than heroin.

As a prescription, fentanyl is available under the brand name Actiq, which is a throat lozenge, or Duragesic, a patch placed on the skin. If a person is hospitalized or undergoing surgery, a healthcare professional may administer fentanyl as an injection called Sublimaze.

When someone with an opioid use disorder misuses fentanyl, it is usually illegally manufactured fentanyl rather than a prescription product. For example, the person may obtain it as powders or pills or add it to containers such as eyedroppers or nasal sprays. Street names for fentanyl include Apache, China Girl, Goodfellas, Great Bear, and Tango & Cash.

How does fentanyl affect the brain?

As with other opioid drugs, fentanyl binds to the receptors in the brain that affect pain and emotion. This causes feelings of well-being (euphoria) and relaxation and relieves pain.

Fentanyl affects people differently, depending on an individual’s size and overall health condition.

The effects are also dependent on:

  • the amount a person takes
  • whether the person takes it in combination with other drugs
  • whether the person is used to taking opioids

Over time, however, the brain adapts to fentanyl, making it difficult for someone to experience positive emotions without the drug. This can lead to addiction.

Medically prescribed fentanyl is available in several forms, including:

  • lozenges (commonly known as lollipops)
  • oral or nasal sprays
  • injections

Medical uses for fentanyl include:

  • anesthesia for people undergoing heart surgery or with a heart condition
  • management of breakthrough cancer pain in people who are already receiving opioid medication for underlying, persistent pain
  • long-term pain management in people who have persistent, moderate to severe chronic pain
  • pain relief for people already taking analgesics or who are opioid-tolerant

Fentanyl patch

For continuous delivery, a transdermal patch can slowly deliver fentanyl through the skin and into the bloodstream for up to 72 hours.

Doctors will only prescribe the fentanyl patch to people who are already tolerant of opioid therapy that is similar in strength. Fentanyl can continue to be effective after removing the patch, as the skin has already absorbed the drug. However, the amount of time it remains effective depends on the individual.

Older people are more likely than younger individuals to experience adverse effects, especially the respiratory depressant effects of fentanyl. Healthcare professionals will typically monitor people in this age group.

Side effects of fentanyl include:

Adverse effects associated with transdermal fentanyl patches include:

  • skin discoloration
  • rash
  • itching
  • swelling at the site of application

A person with a substance use disorder might obtain fentanyl by misusing prescribed medication or acquiring the drug from an illegal laboratory. Misuse of fentanyl includes taking it orally, smoking it, snorting it, or injecting it. One method of use is not safer than another.

Discarded fentanyl patches may still contain significant amounts of the drug. This can result in misuse if someone removes the gel contents from discarded patches.

Illegal drugs, such as heroin and cocaine, are sometimes mixed with fentanyl, which makes the drugs more potent. If someone with a substance use disorder is unaware of the added fentanyl, this can put them at a higher risk of accidental overdose or death.

Treatment options for fentanyl addiction

Treatment for fentanyl addiction is the same as for any opioid use disorder and depends on the severity of the addiction. Treatment may include:

  • an inpatient or outpatient detox program
  • medication treatments to help manage cravings and the possibility of relapse
  • residential and outpatient behavioral treatment programs

A healthcare professional may prescribe medications such as buprenorphine and methadone, which affect the same receptors in the brain as those affected by fentanyl. This helps reduce symptoms of withdrawal. A doctor may also choose to prescribe naltrexone, which stops the effect fentanyl has on the body.

People may consider talking with a therapist for support with their medication use if medication is part of their treatment. Therapy options include:

  • cognitive behavioral therapy, which works on changing behavior and managing triggers and anxiety
  • contingency management, which offers an incentive for negative drug tests
  • motivational interviewing, which counsels the individual based on their unique needs and any conflicting feelings they may have about managing an addiction

As with any opiate, there is a risk of dependency, tolerance, misuse, and addiction with fentanyl. Physical dependence results in withdrawal symptoms when individuals suddenly stop taking the drug.

For someone who is addicted to fentanyl, withdrawal symptoms can start as early as a few hours after they stop taking it. Withdrawal symptoms may include:

People who take fentanyl may develop a tolerance to high doses, meaning that more of the drug is needed to achieve the desired effect.

Sometimes, a person with opioid dependence may take fentanyl as a substitute for heroin. The potency of fentanyl and the potential for incorrect dosing can result in overdose and death.

Fentanyl use can result in death even with one dose, especially if a person accidentally takes it incorrectly.

Signs and symptoms of a fentanyl overdose include:

  • slow or shallow breathing
  • severe sleepiness
  • cold, clammy skin
  • limp body
  • choking
  • discolored skin
  • pinpoint pupils

Many fatal overdoses thought to be from heroin have been from fentanyl. A small dose of fentanyl can be fatal depending on how tolerant someone is and their body size. Coroners’ offices and state crime laboratories do not test for fentanyl unless given a specific reason to do so.

The Food and Drug Administration (FDA) has warned that deaths and overdoses have occurred in people using both the brand-name product Duragesic and generic transdermal fentanyl patches. The FDA also warned that children are at particular risk for accidental death from exposure.


An overdose of fentanyl is an emergency. A person exhibiting the symptoms of overdose should get immediate medical attention. With an overdose of fentanyl, the brain experiences hypoxia. This means it does not get enough oxygen. The condition can lead to coma and even death.

The treatment for overdose is usually naloxone. The medication will reverse the effects of fentanyl and block future effects. However, naloxone only stays in the body for a short time. If a person appears to experience overdose symptoms again, they may require another dose.

Below are some commonly asked questions about fentanyl.

Why do people take fentanyl?

In a medical setting, people take prescribed fentanyl for severe or chronic pain.

Alternatively, some people may take illegally manufactured fentanyl for its heroin-like effect. Sometimes, individuals mix it with other drugs because of its potency.

Is fentanyl addictive?

Yes, fentanyl is addictive due to its potency. It is 50–100 times more potent than morphine.

A person taking prescribed fentanyl can experience dependence, meaning they have withdrawal symptoms when they stop taking the drug. This dependence can sometimes lead to addiction.

How can a person be sure that they’re taking real fentanyl?

Illegally manufactured fentanyl can look like many other drugs. It comes in various forms, including liquid and powder.

Some people claim they can tell they are taking fentanyl, rather than heroin, due to its pale color (which ranges from bright white to off-white) and sweet taste. However, this is not a reliable indicator of whether a person is taking real fentanyl or not.

If a person has naloxone, is fentanyl safe to use?

Prescribed fentanyl is safe when taken as directed. Illegal fentanyl, however, has an unknown amount of fentanyl and may be mixed with other drugs, which may result in harmful behaviors.

A person with opioid use disorder has an increased risk of overdose. Carrying naloxone can provide them with an extra layer of protection from overdose.

Fentanyl is a potent opioid that offers pain relief to those who live with severe acute or chronic pain conditions. A healthcare professional may prescribe it to treat severe pain.

Some people take it illegally in synthetic form. Sometimes, fentanyl is mixed with other illegal drugs. However, people may not always know fentanyl is present.

Fentanyl carries a high risk of dependence and addiction. It can cause harm or death to people with opioid use disorders or who may have accidental exposure to the drug.