Medical gases listed below are administered to a patient for anesthesia, therapy, or diagnosis.

• Oxygen is used to support the respiratory system.
• Nitrous oxide is used as an anesthetic agent in surgery and dental procedures;
• Nitrogen is used to prevent combustion and other chemical reactions.
• Carbon dioxide is used to inflate parts of the body for "keyhole" surgery, mixed with oxygen to stimulate breathing and cryosurgery.
• Medical air is used in administering breathing treatments.
• Helium is used in breathing mixtures for patients with impaired lung functions.