Nitrous Oxide

Nitrous oxide (N₂0) is commonly called "laughing gas." It relieves pain and anxiety during medical procedures. It was first used this way in 1844, when a Connecticut dentist named Horace Wells tried it on himself while having a tooth extracted.

At first, Wells and others thought nitrous oxide would keep patients pain-free during dental procedures and surgery. However, it is not a good painkiller. Today, it is used in dentistry to relax people. It also can make other anesthetics work better.

Nitrous oxide is a colorless gas with a pleasant taste and odor. People first inhale 100% oxygen through a soft nosepiece or mask. Then, nitrous oxide is mixed with the oxygen. Dentists usually use a mixture that is about 20% to 30% nitrous oxide and 70% to 80% oxygen. Nitrous oxide usually starts to work in less than five minutes. When used for mild (conscious) sedation, nitrous oxide may make you feel:

Tingling in your hands and feet

Numbness in your mouth, feet or hands

Heaviness or lightness

Changes in the way you hear sounds (everything sounds far away)

Sleepiness

A sense that everything is wonderful

Nausea

In rare cases, anxiety

Nitrous oxide does not put you to sleep. You can still respond to your dentist's requests and answer questions. Your speech may be slightly slurred, and your responses may be slower than usual. In general, you will be relaxed and cooperative. You will know when you are receiving an injection, and you may even feel it. But you probably won't care. Your breathing and heartbeat will still be normal.

Nitrous oxide is safe. Side effects may include headache, nausea or vomiting. While you are receiving nitrous oxide, tell your dentist right away about any discomfort you feel or concerns you have.

If you have side effects, your dentist will turn off the nitrous oxide and allow you to breathe oxygen for up to five minutes. This flushes the nitrous oxide out of your blood.

You should feel normal and alert once the mask has been removed. However, your motor skills and attention can be affected for as long as 15 minutes after you stop breathing the nitrous oxide. If you leave the dental office sooner than that, ask your dentist if it is okay for you to drive.

People with stuffy noses or breathing problems should not receive nitrous oxide. The gas enters your lungs through your nasal passages, so these must be clear for the gas to work. Nitrous oxide also is not recommended for people with certain lung conditions. These include emphysema, bronchitis and severe chronic obstructive pulmonary disease (COPD).

Nitrous oxide during pregnancy should only be used after talking with your physician and dentist.

If you take medicine for psychiatric conditions, talk to your doctor before receiving any sedatives.

Nitrous oxide is safe for children, but not all children will be able to use it. Children must be able to put up with having the plastic tubes placed in their nostrils. They also must be able to breathe through the nose, and follow instructions from the dentist.