Nasal Cannula Prongs Up or Down? How to Wear One Correctly, Route the Tubing and Fix the Fit

A standard dual-prong nasal cannula sits correctly when the prongs curve downward, just before they go into the nostrils. That curve follows the natural shape of the nasal passage, so the tips rest against the lower part of the nostril instead of pressing up toward the septum. If the cannula you're holding came with its own fitting note from the manufacturer, that note takes priority over everything in this guide; what follows describes the typical two-prong design that ships with most home oxygen and hydrogen-inhalation kits, including the cannulas included with Hydrion inhalation machines.

If you haven't started a hydrogen inhalation session yet and want the broader setup picture first, the beginner's guide to hydrogen inhalation therapy walks through getting started from scratch. This article stays narrowly on one physical question: how the cannula itself should sit on your face, and why it slips, rubs, or feels wrong when it doesn't.

• The prongs point downward into the nostrils rather than straight in or angled upward.
• Tubing runs up and over each ear, the way glasses arms do, then down to a slide or clip under the chin that you tighten until the fit is snug.
• Most slipping, rubbing, or "it keeps falling out" complaints trace back to that chin slide sitting in the wrong spot, not to a faulty cannula.
• Redness that doesn't settle, nosebleeds, or breathing that feels harder with the cannula in are reasons to stop and ask for help rather than keep adjusting on your own.

Which way should the prongs point?

Hold the cannula so the two prongs curve downward, then guide them gently into the nostrils with that curve following the slope of the nasal passage (source: Administering Oxygen via a Nasal Cannula, Craven & Hirnle). Inserted the other way around, the tips tend to push upward into the septum, which is the usual cause of a cannula that feels wrong from the first breath rather than after an hour of wear. A separate patient-facing description of self-applying a cannula confirms the same orientation and adds that the fit should end up snug, not tight (source: Set Up Oxygen with a Nasal Cannula, Docsie).

How far the prongs sit inside the nostril varies by design and by face shape, so this guide doesn't give a specific depth to aim for; follow the depth that feels like a light rest against the inside of the nostril, not a reach that feels like it's touching higher up. If you're comparing cannula shapes, lengths, or sizing across different kits, a dedicated guide to nasal cannula types covers how those variations differ and what each is built for; this article assumes you already have the cannula in hand and need it to sit right.

Routing the tubing over your ears and the chin slide

Once the prongs are seated, the tubing on each side runs up and loops over the top of the corresponding ear, similar to how eyeglass arms rest there. Both lengths then come down under the chin to a small plastic slide, which you move upward along the tubing until the cannula sits snugly against your face, then ease back slightly so it stops just short of pulling on the nostrils or digging into the skin behind the ears (source: Craven & Hirnle, Fundamentals of Nursing). The slide is doing most of the work here: move it one notch at a time and check how the fit changes before deciding you need to reposition the tubing itself.

What a correct fit feels like versus what means it needs adjusting

What you notice	What it usually means
The cannula stays in place through normal head movement without you thinking about it.	The fit is correct; leave the slide where it is.
The cannula slides down your face or drifts to one side within minutes.	The chin slide is too loose; move it up a notch and retest.
The tubing feels like it's pulling at the corner of your nostrils.	The slide is too tight; ease it back slightly.
A sore spot or mark forms where the tubing crosses an ear after a long session.	The tubing is rubbing at that point; reposition the loop or add soft padding there.
One prong keeps popping out of the nostril during the session.	The routing or slide position has shifted; reset both rather than just pushing the prong back in each time.

Common fit problems and practical fixes

Most complaints about a cannula that "doesn't work right" come down to a handful of recurring issues, each with a straightforward fix rather than a reason to force the device into a different shape.

• Slipping during normal movement: this almost always means the chin slide needs to move up slightly; retest after each small adjustment instead of over-tightening in one go.
• Rubbing or a mark behind an ear: shifting the loop to a slightly different spot on the ear, or adding a small piece of soft padding where the tubing crosses it, addresses this directly (source: Craven & Hirnle, Fundamentals of Nursing).
• Prongs that feel like they reach further into the nostril than expected: re-check the curve and the angle against how the cannula is designed to sit before assuming the device itself is wrong; trimming or reshaping a standard dual-prong cannula isn't something this guide recommends, since that changes a design the manufacturer tested as a whole.
• A prong that keeps dislodging from one nostril: treat a cannula that repeatedly pops out as a sign the slide or ear routing has shifted, and reposition it promptly rather than letting it sit loose for the rest of the session (source: Craven & Hirnle, Fundamentals of Nursing).

When to stop and get help from a clinician or supplier

A fit adjustment solves slipping, rubbing, and minor discomfort. It doesn't solve everything, and a few signs are worth treating as a stopping point rather than something to work around.

• Redness, soreness, or skin breakdown at the nostrils or ears that doesn't settle after you've corrected the fit is a reason to change your approach, not push through it.
• Nosebleeds, or marked discomfort that continues after a proper refit, are worth mentioning to whoever supplied the cannula.
• If breathing feels harder with the cannula in place rather than easier or unchanged, stop and check with a clinician before continuing.
• If the cannula that came with a kit genuinely doesn't match your face shape no matter how you adjust it, asking the supplier about a different size is more reliable than improvising a workaround.

Before you start a session with a Hydrion machine

The same cannula that you've just fitted is what connects to the machine itself, so the checks above apply before a session starts and not only to how it sits on your nose and ears. The Hydrion Zenith, for example, ships with two nasal cannulas, an adapter tube, and two cannula ports built into the unit, so two people can run a session side by side using their own correctly fitted cannula.

Before switching the unit on, look over the full length of tubing for kinks or tight bends, and confirm the cannula is seated firmly where it connects to the adapter tube. Where you place the machine matters almost as much as the cannula fit itself: give it enough room that the tube reaches you without being pulled taut, which matters a little more on a model like the Zenith, since it's moved around on its built-in wheels rather than dragged into position by the tubing. For anything about ventilating the room or how long a session should run, the guide to hydrogen safety limits and room ventilation covers that separately, and for cleaning and storing the cannula and tubing between sessions, the machine care guide goes through the water, filter, and tubing routine in full. The user manual that came with your specific model is the final word on setup and controls; this guide only covers the cannula and how it sits.