Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.

America is in the midst of a fentanyl crisis. There were 71,238 fentanyl overdose deaths in the United States in 2021. The Drug Enforcement Administration (DEA) states, “fentanyl is involved in more deaths of Americans under 50 than any cause of death, including heart disease, cancer, homicide, suicide and other accidents.”

Despite this, during surgery your anesthesiologist injected fentanyl into your IV as part of your anesthetic. Is that safe?


As a street drug, fentanyl overdose is a critical problem in the United States, but anesthesiologists administer fentanyl to most patients, and do so safely. I review charts from all regions of the U.S., and virtually every anesthetic includes the safe use of fentanyl. Fentanyl was introduced in the 1960s when it was first patented under the brand name Sublimaze, and fentanyl quickly became the most commonly administered narcotic by anesthesia providers. In operating room anesthesia, the narcotic fentanyl is a clear liquid usually marketed in vials of two milliliters or five milliliters.

Why do anesthesiologists utilize fentanyl? Most surgeries cause pain, and our pharmaceutical options for relieving pain include local anesthetics, anesthesia gases,  or narcotics. When possible, we advocate for the injection of local anesthetics by the surgeon or the anesthesiologist to block postoperative pain. Local anesthetics include lidocaine, bupivacaine (also known as Marcaine), or ropivacaine. In addition, most general anesthetics include a potent inhaled anesthesia gas such as sevoflurane. Sevoflurane vapor maintains unconsciousness, blocks memory, and renders a patient pain-free, but when the surgery concludes, the anesthesia gases are turned off so that the patient will awaken. As the anesthesia gas is exhaled, a patient becomes progressively more alert, and will eventually be awake enough to feel surgical pain. The intravenous injection of a narcotic medication such as fentanyl is a common antidote to postoperative pain.

Narcotics relieve pain, but also have the undesirable side effects of respiratory depression, sedation, nausea, and constipation. Narcotics available to an anesthesiologist include morphine, Demerol, Dilaudid, or fentanyl. We commonly administer fentanyl because it has a rapid onset and rapid offset of its effect when compared to the other three drugs. The onset of action of intravenous fentanyl is less than 60 seconds. Its peak effect is at 2–5 minutes, with a half-life of 90 minutes and a duration of action of 30–60 minutes. In contrast, intravenous morphine has a slower peak effect at 5–15 minutes, with a longer half-life of 1.5–2 hours, and a longer duration of action of 3–4 hours. Because the peak effect of morphine, Demerol, or Dilaudid does not occur as rapidly as fentanyl, titrating the intravenous loading of morphine, Demerol, or Dilaudid is a slower process. Fentanyl’s rapid onset of narcotic effect is desirable because anesthesia providers quickly know whether an additional dose is necessary to achieve the titrated level of pain relief we seek. We can administer an IV dose of fentanyl every five minutes, waiting only those five minutes to evaluate how effective the preceding dose was.

Respiratory Depression:

The most serious side effect of intravenous fentanyl in anesthesia usage is the same side effect that makes street fentanyl dangerous, and that’s the side effect of respiratory depression. In layman’s terms, an excessive dose of fentanyl quickly causes a patient to stop breathing. The medical term for cessation of breathing is apnea. In an anesthesiologist’s hands, apnea is easily handled because we are skilled at ventilating oxygen into a patient’s lungs safely via a mask or an airway tube.

Street overdoses of fentanyl are best treated with naloxone (brand name Narcan). Nasal Narcan is now approved for over the counter (OTC) sale in the United States. In a medical setting, intravenous Narcan is injected to reverse a narcotic overdose. Injection of one ampule of Narcan (0.4 mg) will completely reverse narcotic apnea and unconsciousness in an overdosed patient in less than a minute.

The protocol for treating an emergency room patient who is unconscious on admission for unknown reasons includes an empirical intravenous injection of Narcan. If the patient’s coma was caused by any narcotic overdose, the patient will awaken within seconds.

Fentanyl is one hundred times more potent than morphine.  Medical fentanyl doses are prescribed in micrograms, while morphine is prescribed in milligrams. One microgram is only 1/1000 of a milligram. A narcotic as potent as fentanyl is typically only utilized by MDs expert at handling apneic patients, and the IV antidote Narcan is always immediately available. Most medical doctors other than anesthesiologists never prescribe intravenous fentanyl. Your general practitioner or primary care doctor will never prescribe fentanyl. A cardiologist may prescribe IV fentanyl sedation for a procedure such as a cardiac catheterization, or a or surgeon may prescribe fentanyl for a superficial excision surgery, but anesthesiologists are typically the only physicians who pick up a fentanyl ampule, insert a needle and syringe into the ampule, and then inject the drug into a patient’s IV. In the intensive care unit (ICU), fentanyl can be used to sedate patients who already have a breathing tube (endotracheal tube) in their windpipe, and who are on a mechanical ventilator. An ICU physician will write an order for the dosing of intravenous fentanyl, and the ICU nurse will be in constant attendance to monitor the patient’s vital signs and level of sedation.


Are you at risk for becoming an addict because your anesthesiologist gives you doses of intravenous fentanyl? No. Most patients have no idea they received IV fentanyl as part of their anesthetic care. The effects of fentanyl wear off within several hours after the end of the surgery, and there is no data that a patient will have a craving for additional fentanyl. After surgery, hospital inpatients who have postoperative pain are typically treated with longer acting narcotics such as morphine or Dilaudid. After surgery, outpatients who have postoperative pain are typically treated with narcotic pain pills such as Oxycontin or Norco. There is no pill form of fentanyl that a patient goes home with, or that a patient can overdose with.

Note that in medical settings, fentanyl can be given by means other than IV injection:


Can medical fentanyl be stolen, find its way to the streets, and be a cause of overdose deaths of non-medical people? No. The DEA forces all hospitals, surgery centers, and medical offices to keep a strict tally of all narcotics and controlled substances. At the end of every day, a precise count of all ampules of fentanyl is done, and unless one of the doctors or nurses falsifies their count, it is unlikely any fentanyl escapes a medical facility and winds up in the hands of dealers, addicts, or individuals in the outside world.


It’s true that medically administered intravenous fentanyl can cause a person to stop breathing, but if an anesthesiologist is present watching every breath, you’re safe. When an airway specialist is present and fentanyl is administered in a hospital operating room, an emergency room, an ambulatory surgery center, or a physician’s office operating room, this represents safe care in the United States today. Don’t worry if you hear your anesthesia provider is going to give you fentanyl. It’s OK. Medical administration of fentanyl has been going since the 1960s. Deaths from fentanyl overdose in a medical setting would be almost unheard of.



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