Laughing gas, which is otherwise known as happy gas, is a chemical compound called nitrous oxide (N₂O). It was produced for the first time by the English chemist Joseph Priestley in 1775, but was later popularized by Sir Humphrey Davy in the 1790s. At room temperature, nitrous oxide does not have any color and is not inflammable. However, it has a pleasant odor and a sweet taste. Laughing gas or nitrous oxide has various uses, but, it is very popular as a clinical sedative, especially in dental procedures. While nitrous oxide is used as an oxidizer in rocket motors, it increases the power output of engines in motor racing. It is also an approved food additive and is used in the form of an aerosol spray propellant. It is used to fill packets of fries and other snacks, in order to displace bacteria-inducing oxygen. Nowadays, it is used for recreational purposes as a dissociative drug, but such activities are under the scanner. Clinical Use Medicinal use of laughing gas is very different from its industrial uses and is mainly based on its anesthetic and analgesic properties. It is commonly used by dentists, as part of sedation dentistry. Pure form (N₂O) cannot be used for longer durations, as it lacks oxygen and this may lead to unconsciousness or death. Hence, for clinical use, nitrous oxide is combined with oxygen, in order to lengthen the period of its use, in a safe manner. There should be a minimum of 30% oxygen in the mixture, but nowadays, the preferable ratio is 70% oxygen to 30% nitrous oxide. The mixture is administered to the patient through a nasal hood. Nowadays, an additional vacuum machine is also fitted to the mask of the patient in order to suck away his/her exhale. This is done to avoid the doctor and other staff getting affected by the exhalation (with laughing gas) of the patient. The patient may feel lightheaded during the initial stages, but the degree of sedation depends upon the concentration of nitrous oxide and the period of administration. The first stage of sedation will be like a tingling sensation in the arms and legs, followed by a warm sensation, which is the second stage. During the third stage, the patient experiences a floating, euphoria-like sensation. The fourth stage makes the patient feel sleepy and he won't be able to speak or move. A feeling of nausea can be inferred as one of the first signs of over-sedation. Side Effects Owing to its sedative property, nitrous oxide or laughing gas is widely abused. As the effect of single inhalation of this gas lasts only for a few minutes, the abusers tend to inhale it for longer durations. This is one of the major causes for the serious side effects of laughing gas. If a person inhales it for longer durations, the rate of breathing may slow down, thereby affecting the air supply to the lungs. Shortage of oxygen may also lead to brain damage. The condition may also result in coma. If the person develops vomiting and loses consciousness, there are chances of choking and even death. Laughing gas is considered a comparatively safer sedative, but may cause some side effects, if administered in very high doses or for a very long period. This may also happen, in case of any error in the ratio of laughing gas and oxygen.

• As mentioned earlier, nausea is one of the laughing gas side effects. The most common reason is the error in the ratio of laughing gas and oxygen. If the amount of laughing gas is more than 70%, nausea may occur.
• If more than 90% of the mixture is composed of laughing gas, then the patient may lose consciousness and there is a very good chance of brain or organ damage, due to lack of oxygen (asphyxiation). Other possible side effects are pneumonia, surgical wound infections and even heart attack.
• Side effects of laughing gas may include numbness in the arms and legs, fatigue, dizziness and headache. In some rare cases, it may cause mental confusion, as it is said to affect the vitamin B12 reserve of the body. Deficiency of vitamin B12 may lead to neurological problems.
• Apart from the above mentioned short-term side effects, regular use of laughing gas (moderate or high doses) may lead to long-term side effects. They include nerve damage, motor disorders, numbness of limbs and impaired attentiveness.
• Administration of nitrous gas should be done by a doctor or a qualified health professional. It should not be directly inhaled from the dispenser, capsule or gas bottle, as this gas may cause internal burning and even lung collapse.
• Pregnant women; people with asthma, other respiratory diseases and pulmonary hypertension and those with otitis, decompression sickness or fractured ribs must avoid use of laughing gas. Those with phenylketonuria (a genetic disorder), must also refrain from using it.
• A combination of alcohol and laughing gas can also prove harmful for the user. Those who use it with other illegal drugs may also suffer from severe and life threatening side effects. It should not be used by those who take antidepressant drugs.
• Long-term exposure as in case of abusers, dentists and dental assistants, may also lead to weakness, infertility, miscarriage and pre-term delivery. Even the liver, kidneys and the brain may get damaged. It is also linked to an increased risk of cancer in females. If used for a long period, laughing gas may hamper with the production of blood cells in the bone marrow. Such people may also develop megaloblastic anemia.

Though laughing gas is considered safe for medicinal purposes, possibility of side effects cannot be ruled out. However, refrain from using it for recreational purposes or as a dissociative drug and it is important to make sure that you don't drive after using this gas. If you are facing any discomfort (due to laughing gas sedation) during a dental procedure, inform the doctor about it. Otherwise discuss the matter with the dentist, beforehand. Don't laugh it away, as laughing gas can be harmful and sometimes even fatal for you, if not administered properly. Disclaimer: This article is for informational purposes only and should not be used as a replacement for expert medical advice.