Which is a typical sign of hypoxia?

• A. Cyanosis
• B. Weight gain
• C. Blurred vision
• D. Bradycardia

Answer: (A)

When oxygen levels in the blood drop, one of the most recognizable signs is cyanosis—the bluish or dusky discoloration of the lips, tongue, and fingernails. This happens because there’s more deoxygenated hemoglobin in the blood, which changes its color and becomes visible in the skin and mucous membranes. Cyanosis is a classic cue that tissues aren’t getting enough oxygen, making it the best answer for a typical sign of hypoxia.

Weight gain isn’t a direct sign of hypoxia and can arise from many other factors; blurred vision isn’t a standard or specific sign of low oxygen, and bradycardia is not typical in hypoxia—usually the heart rate rises (tachycardia) to try to increase oxygen delivery.