What should you know about nonin pulse ox?

The device uses light passing through the finger to estimate how much oxygen is carried in the blood. It also displays a pulse rate. A reading can be affected by cold fingers, movement, poor circulation, nail products, bright light, or an improperly positioned sensor. A single unexpected result should be checked again after resting and warming the hand. The number is one piece of information, not a diagnosis or a replacement for an examination.

Sit quietly, keep the hand relaxed, and place the sensor as directed in its instructions. Remove anything that blocks the light if needed, and wait for the display to settle. Record the reading alongside the time and your symptoms if a clinician has asked you to monitor it. Do not change prescribed oxygen or other treatment based on the device alone. For a broader explanation, see [Pulse Oximeter](/technology/pulse-oximeter/).

Seek urgent medical help for severe breathlessness, blue or grey lips, chest pain, fainting, new confusion, or marked drowsiness, even if the displayed reading seems reassuring. Arrange prompt medical advice for a persistently unexpected reading, worsening breathing, or a clear change from your usual result. A [GP Consultation](/treatments/consultations-and-assessment/gp-consultation/) can help interpret readings in the context of your health and examination.

Ask which readings are relevant for you, how often to measure, whether your device and sensor placement are suitable, and what symptoms should prompt urgent help.