CPAP Aerophagia: Why You're Swallowing Air and How to Stop

You wake up looking three months pregnant, belching, with a stomach that feels tight and sore. It’s an unglamorous side effect that nobody warns you about, and it has a name: aerophagia — literally, air eating.

What’s happening

CPAP pushes air toward your airway. Two tubes lead away from your throat: the trachea, which goes to your lungs, and the oesophagus, which goes to your stomach. A ring of muscle at the top of the oesophagus normally keeps the second one closed.

When pressure is higher than that muscle comfortably resists — especially while it’s relaxed in sleep — some air goes down the wrong pipe. Over seven hours, a small amount per breath adds up to a genuinely uncomfortable volume of gas in your gut.

Which then has two exits, both of which you’ll become familiar with.

The likely causes

Pressure is higher than you need. The most common reason. This is where the “more pressure is better” instinct causes trouble — the right pressure is the lowest one that keeps your airway open, not the highest you can tolerate.

You’re fighting a leak. A leaking mask makes you swallow and adjust unconsciously. Fixing the leak sometimes fixes the aerophagia by itself. See fixing mask leaks.

Mouth breathing on a nasal mask. Air entering the mouth is closer to the oesophageal opening. A chin strap or full face mask can change the picture.

Sleeping flat on your back. Gravity stops helping. This is the easiest variable to test.

Reflux. GERD and sleep apnea coexist often, and a weakened lower oesophageal sphincter makes swallowed air more likely to cause symptoms. If you have reflux, treating it may improve both.

What to try, in order

1. Sleep on your side

Free, immediate, and effective for a lot of people. It also usually reduces your apnea severity, so there’s no downside.

If you keep rolling onto your back, a positional aid — even a pillow wedged behind you — helps.

2. Elevate the head of your bed

Not more pillows, which bends your neck and can worsen airway collapse. Raise the whole head end of the bed by a few inches with risers, or use a wedge pillow that supports your torso.

This helps with reflux at the same time, which is a common companion problem.

3. Fix any leak

Fighting air escaping around your mask promotes swallowing. Re-fit the mask lying down, check the cushion isn’t worn, and replace it if it’s gone shiny or tacky.

4. Ask about exhale relief

This is the most common clinical fix. EPR (ResMed), Flex (Philips), and similar features drop the pressure slightly while you breathe out. Less pressure on the out-breath means less air being forced past the oesophageal sphincter.

It’s an adjustable setting and often solves aerophagia outright. Ask specifically: “I’m getting significant aerophagia — can we try increasing exhale relief?”

5. Ask whether your pressure can come down

If exhale relief isn’t enough, the question is whether your prescribed pressure is higher than you actually need. That’s a data question your clinician can answer by looking at what pressures your machine is actually using and what your residual AHI is.

6. Consider whether an APAP would help

If you’re on a fixed pressure, an auto-adjusting machine spends much of the night below your maximum rather than at it, which reduces the total exposure to high pressure. The NIH describes APAP as self-adjusting, versus CPAP’s constant pressure¹ . Worth raising if aerophagia persists. See CPAP vs APAP vs BiPAP.

7. Ask about bilevel

For people who need high pressures and can’t tolerate the aerophagia, bilevel therapy — a distinctly lower pressure on exhalation — is sometimes the answer. It’s a clinical decision with its own coverage requirements.

Things that help around the edges

• Avoid carbonated drinks and large meals close to bedtime.
• Don’t eat within about three hours of sleeping.
• Gentle movement in the morning — walking helps gas move.
• Simethicone is available over the counter for gas symptoms; check with a pharmacist if you take other medications.

None of these treat the cause, but they make the mornings more bearable while you work on the settings.

When to see a doctor promptly

Aerophagia is uncomfortable rather than dangerous, but abdominal symptoms deserve attention when they’re severe. See your doctor if you have significant abdominal pain rather than bloating, if you’re vomiting, if symptoms came on suddenly having been fine for months, or if you have chest pain — which needs assessing on its own terms rather than being attributed to gas.

The thing worth saying

People quit CPAP over aerophagia, and it’s a shame, because it’s one of the more fixable side effects. Between side sleeping, bed elevation, fixing leaks, and exhale relief, most people get it under control.

If you’ve been enduring it for months without telling anyone, that’s the step you’re missing.