What is the route of administration for oxygen?

• A. Oral
• B. Inhalation
• C. Intravenous
• D. Subcutaneous

Answer: (B)

Oxygen must be delivered by inhalation because the lungs are where oxygen gas enters the bloodstream through the alveoli. Breathing in oxygen-rich air brings the gas directly to the airways and lungs, allowing it to diffuse into the blood quickly, which is essential for rapid oxygenation.

Oral administration would route the gas to the digestive system, where it’s not absorbed effectively into the bloodstream and wouldn’t raise blood oxygen promptly. Intravenous delivery involves the veins and blood, not gas exchange, so pure oxygen cannot be given that way. Subcutaneous administration places gas under the skin and again wouldn’t reach the lungs. In practice, oxygen is given by inhalation through devices like a nasal cannula or face mask to ensure it reaches the lungs for diffusion into the blood.