A simple oxygen mask and a non-rebreather mask are different interfaces. They should not be substituted for each other because both fit over the nose and mouth. The prescription, oxygen source and exact mask instructions must agree before use.
Recognise the equipment
A simple face mask has openings that allow gas to move in and out and does not have a reservoir bag. A non-rebreather uses a reservoir and a valve arrangement designed to reduce mixing with room air and exhaled gas. Other reservoir-mask designs also exist, so the presence of a bag alone is not a complete identification method.
Read the packaging or model description, and ask the clinical team to confirm the supplied mask. A photograph can help resolve uncertainty, but it should not replace the manufacturer's instructions or a demonstration of the prescribed setup.
Understand what each mask changes
A simple mask provides a variable oxygen mixture affected by fit, source flow and breathing pattern. A non-rebreather can provide a higher oxygen concentration when correctly supplied and used, but does not guarantee one precise percentage. The BTS oxygen guideline discusses their different roles in monitored care.
Neither mask generates oxygen. Neither can make an inadequate source deliver more than its capacity, and neither provides the ventilatory assistance of non-invasive ventilation or a ventilator. An acceptable-looking oximeter number does not rule out other serious breathing problems.
Confirm the home plan
If a mask is prescribed at home, ask for its exact name, the required source and setting, the monitoring plan and the response to problems. A nasal-cannula prescription cannot simply be copied to a mask. Some interfaces need a minimum flow for safe use; the clinician and device instructions must determine that requirement.
Ask the supplier to demonstrate correct assembly and show which parts should remain unobstructed. Do not tape over openings, remove valves or add connectors. If a reservoir behaves differently from the demonstrated setup, seek help according to the plan instead of experimenting with settings.
Keep the handover clear
When ordering replacements, retain the model details rather than asking only for “an oxygen mask”. Confirm whether components are single-use and follow the stated cleaning or replacement instructions. Tell the team about poor fit, skin discomfort or difficulty tolerating the interface so an appropriate alternative can be considered.
An unexpected need for a different mask or more oxygen warrants clinical reassessment. Severe breathlessness, unusual drowsiness, confusion or chest pain requires urgent medical attention. For a different question—how a selected oxygen percentage is delivered—read the .