How Nitrous Oxide Works

Horace Wells was the first person to use nitrous oxide in dentistry.
Horace Wells was the first person to use nitrous oxide in dentistry.
© Corbis

Horace Wells was a prominent dentist in Hartford, Connecticut, in the 1830s. Like many dentists of his day, Wells was deeply troubled by the agonizing pain his patients suffered during routine procedures like pulling diseased or rotten teeth without anesthesia — ouch!

In 1844, Wells attended a demonstration — part scientific presentation, part sideshow spectacle — by showman Gardner Colton on the mysterious power of nitrous oxide [source: Gifford]. Colton had briefly attended medical school where he and his classmates experimented with the exhilarating properties of the colorless, odorless gas [source: Encyclopaedia Britannica].

During Colton's show, he administered nitrous oxide to audience volunteers who would burst into fits of giggling befitting a substance commonly known as "laughing gas." At the Hartford show attended by Wells, a delirious volunteer injured his leg on stage, but when Wells quizzed the man about it, he couldn't remember any pain [source: Gifford].

Back at his office the next day, Wells climbed into his own operating chair and asked a colleague, with the help of Colton, to administer nitrous oxide while pulling one of Wells' own troubled teeth. The tooth was yanked and Wells reported feeling not "so much as the prick of a pin" [source: Gifford]. The three men, it seemed, had invented painless dentistry.

Wells was thrilled, and after some training from Colton, went on to perform dozens of similar procedures, each with pain-free results. Believing he had discovered a miracle anesthesia, Wells scheduled a public demonstration of his nitrous oxide technique in 1845 for a crowd of Harvard professors and medical students in Boston.

The big show didn't go so great. In fact, it was a full-on disaster complete with its own name, the "humbug affair." Apparently, Wells' patient, after being administered the nitrous oxide, cried out when Wells began to extract his tooth. Whether it was a moan of delirium, a joke or real pain, the crowd of medical students taunted Wells with jeers of "Humbug!" and "Swindler!" [source: Gifford].

As we know today, Wells was no swindler. The Hartford dentist never recovered from his failed demonstration — he sank into an irrecoverable depression aided by ether and chloroform — but his discovery of nitrous oxide as a powerful anesthetic was recognized by the American Dental Association in 1864 [source: Gifford]. Sadly, Wells had taken his own life decades earlier.

The story of nitrous oxide is long and complex, and its dual personality — miracle pain reliever and dangerous recreational drug — makes it just as controversial today as it was in the 1840s.

History of Nitrous Oxide

Seventy years before Horace Wells began experimenting with nitrous oxide as a dental anesthetic, an Englishman named Joseph Priestly was on the verge of a series of momentous discoveries that would forever change our understanding of chemistry.

Priestly was one of the great Enlightenment thinkers, a contemporary of Benjamin Franklin and a prolific writer on every imaginable subject, from politics to religion to the nature of electricity [source: Chemical Heritage Foundation].

In the 1770s, Priestly turned his attention to the study of "airs," as gases were called in the 18th century. Living next to a brewery, Priestly had access to a nearly unlimited supply of carbon dioxide bubbling from the fermentation tanks. He adopted techniques used by Stephen Hales, who invented a device called a pneumatic trough to collect and isolate gases respired by plant leaves [source: Encyclopaedia Britannica].

With his own pneumatic trough, Priestly was able to isolate and identify eight gases — a research record that stands today — including oxygen (O2), nitrogen (N2), hydrogen chloride (HCI), sulfur dioxide (SO2) and nitrous oxide (N2O), or what Priestly called "nitrous air, diminished" [source: Zuck et al.].

It was another English chemist, Humphry Davy, who would shed further light on the mysterious properties of nitrous oxide. As laboratory superintendent of the Pneumatic Institute, Davy investigated the use of different gasses as curative therapies [source: Zuck et al].

In those days, self-experimentation was perfectly normal, and Davy thought nothing of huffing random gasses — including toxic fumes like carbon monoxide and carbonic acid — in search of scientific evidence [source: Watt].

In 1800, a presumably lightheaded Davy published a thick tome on nitrous oxide, but only made passing mentioned of its anesthetic properties, writing, "As nitrous oxide appears capable of destroying physical pain, it may probably be used with advantage during surgical operations in which no great effusion of blood takes place" [source: Zuck et al.].

It would be another 40 years before nitrous oxide was rediscovered by Wells and eventually accepted as a wonder drug for surgery.

Uses of Nitrous Oxide

A 10-year-old girl receives nitrous oxide as an anesthetic in a hospital emergency room in France.
A 10-year-old girl receives nitrous oxide as an anesthetic in a hospital emergency room in France.
© Peet Simard/Corbis

The best-known uses of nitrous oxide are as a medical anesthetic and analgesic. An anesthetic causes a patient to lose touch with all sensation of pain — and often lose consciousness — while an analgesic simply lessens the severity of the pain. Tylenol, for example, is an analgesic.

Worldwide, nitrous oxide is the No. 1 inhaled anesthetic in the medical profession, always administered as a 50/50 blend of nitrous oxide and pure oxygen [source: Oglesbee]. As a patient in the U.S., you're most likely to encounter nitrous oxide at the dentist's office, but in Europe, Canada and Australia it's commonly used as a pain reliever during childbirth [source: ACNM].

The chief advantages of nitrous oxide as a pain reliever are that it delivers immediate and powerful analgesic effects and can be cut off just as quickly, with patients recovering full sensation within minutes of removing a nitrous inhalation mask [source: ACNM]. Emergency medical personnel use nitrous oxide for quick pain relief during a variety of medical situations, including heart attacks, severe burns, kidney stones, fractures and dislocations [source: Oglesbee].

So how does this gas work? When nitrous oxide is inhaled, the gas enters the blood stream through the lungs and travels quickly to the brain, where it triggers the release of the body's natural opioids, endorphins and dopamine [source: ACNM]. The anesthetic effect of nitrous oxide is achieved by temporarily stabilizing neuron activity in the brain [source: Oglesbee].

In the food industry, nitrous oxide is a highly effective propellant for dispensing fatty liquids like oil and heavy cream. To dispense whipped cream, nitrous gas is compressed into a liquid and mixed with heavy cream inside sealed, pressurized canisters. Because the liquid nitrous oxide displaces all oxygen in the can, an unopened canister of whipped cream will never go rancid. Nitrous oxide is highly soluble in fat, and when pressure inside the canister is released, the liquid nitrous instantly turns to gas, expanding the volume of the cream four-fold [source: Weingarten].

Another popular use of nitrous oxide is as a fuel additive in car racing. Read the full HSW article for all of the details on how an injection of nitrous oxide improves engine performance, but here's the gist: In an internal combustion engine, oxygen is critical for igniting the fuel injected into the engine. When nitrous oxide is heated to 570 degrees F (~300 C) — racing engines run hot — it splits into nitrogen and oxygen. Adding compressed nitrous oxide to an engine significantly raises oxygen levels, which translates to more fuel being burned and more horsepower [source: Hot Rod Network].

The final popular use of nitrous oxide is as a recreational drug. More on the "buzz" and adverse side effects of nitrous oxide abuse on the next page.

Recreational Use (and Abuse) of Nitrous Oxide

A sign advertising laughing gas is prominently displayed in the party island of Ko Phangan, Thailand.
A sign advertising laughing gas is prominently displayed in the party island of Ko Phangan, Thailand.
Matthew Micah Wright/Lonely Planet Images/Getty Images

Centuries before buzz-chasing ravers sucked on balloons of nitrous oxide inside London dance clubs, there was Humphry Davy, the self-experimenting scientist who stumbled upon nitrous oxide's more pleasurable properties. Starting in 1799, Davy invited a growing circle of scientific colleagues, philosophers, writers and statesmen to partake of this euphoric gas during wild, late-night huffing parties [source: Watt].

Throughout the entirety of the 19th and early 20th century, the recreational use of nitrous oxide among high-society huffers was well-documented. Several early motion pictures were titled "Laughing Gas," including a 1914 short starring Charlie Chaplin as a prankster posing as a dentist.

In the 1970s, balloons filled with nitrous oxide (often just called "nitrous" on the street) began appearing at rock festivals and sold for 25 cents a pop [source: Wolfson]. Unlike the prolonged exposure preferred by Davy — in which the scientist experienced deeply hallucinatory revelations — a balloon full of nitrous delivers a numbing, swelling dizziness followed by the irrepressible urge to giggle.

In the U.K., where nitrous oxide is legal to possess for recreational use, 7.6 percent of young people ages 16-24 interviewed in 2014 said they had used nitrous oxide in the past year — about twice as many as had experimented with the popular club drug ecstasy or with cocaine [source: Wolfson].

Nitrous oxide is illegal to sell or possess in the United States for recreational use. But is inhaling N20 actually bad for you? Prolonged exposure to nitrous oxide will steal oxygen from brain cells, killing them in the process (apoptosis). The gas can also damage the protective covering of neurons called myelin, which may lead to long-term learning difficulties. But the real danger of huffing nitrous has little to do with brain chemistry — the most serious "side effects" are broken bones and head traumas suffered by people who fall down while buzzed [source: Go Ask Alice].

Author's Note: How Nitrous Oxide Works

Mom, stop reading this. OK, is she gone? Truth be told, in my youth, I may have inhaled nitrous oxide once or twice outside of a dental setting. I did a lot of stupid things as an anxious, self-conscious teenager trying to impress his friends. From what I remember, huffing nitrous felt like a limb falling asleep, except the limb was my head. Even as a stupid teenager, I knew this couldn't be good for the "crain bells," so I found ways to avoid it. The last time I inhaled nitrous was in a Mexican dentist's office, where laughing gas is administered for procedures as routine as a vigorous flossing. All I remember is hearing The Beatles on the sound system and thinking, "Man, The Beatles are amazing!" Next thing I knew, I was spitting into a napkin and ushered out into the glaring daylight, still slightly dazed and amused.

Related Articles


  • American College of Nurse Midwives. "Position Statement: Nitrous Oxide for Labor Analgesia." December 2009 (June 22, 2015)
  • Chemical Heritage Society. "Joseph Priestly" (June 22, 2015)
  • Encyclopaedia Britannica. "Gardner Quincy Colton: American anesthetist and inventor." (June 22, 2015)
  • Encyclopaedia Britannica. "Stephen Hales: English scientist." (June 22, 2015)
  • Gifford, Emily E. "Horace Wells Discovers Pain-free Dentistry." (June 22, 2015)
  • Go Ask Alice. "Nitrous Oxide." March 9, 1995 (June 22, 2015)
  • Jay, Mike. "'O, Excellent Air Bag': Humphry Davy and Nitrous Oxide." The Public Domain Review. May 8, 2014 (June 22, 2015)
  • Oglesbee, Scott. "Using Nitrous Oxide to Manage Pain." Journal of Emergency Medical Services, vol. 39, issue 4 (June 22, 2015)
  • Watt, Jeremy. "How Humphrey Davy Discovered Nitrous Oxide." A Moment of Science. Feb. 9, 2012 (June 22, 2015)
  • Weingarten, Hemi. "What is Laughing Gas Doing in My Whipped Cream?" Fooducate. May 7, 2013 (June 22, 2015)
  • Wolfson, Sam. "Is the growth in nitrous oxide misuse a laughing matter?" The Guardian. Aug. 13, 2014 (June 22, 2015)
  • Zuck, David; Ellis, Peter; and Dronsfield, Alan. "Nitrous oxide: are you having a laugh?" Education in Chemistry, March 2012 (June 22, 2015)