What is Obesity Hypoventilation Syndrome (OHS)?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Obesity Hypoventilation Syndrome (OHS) is a serious breathing disorder that affects people with obesity, where excess body weight makes it difficult to breathe deeply enough—especially during sleep. This shallow breathing causes too little oxygen and too much carbon dioxide to build up in the blood, which can lead to fatigue, morning headaches, shortness of breath, and, if untreated, heart and lung complications.

If you're experiencing symptoms like daytime sleepiness, loud snoring, or breathlessness, it's important not to guess. Understanding what's happening in your body is the first step toward feeling better—and you don't have to wait for an appointment to start. Take a free, instant, online symptom check to gain personalized insight into your symptoms and clear guidance on what to do next.

Reviewed for medical accuracy: 07/15/2026

Important Next Steps

Learn if obesity hypoventilation causes your symptoms Discover likely causes of obesity hypoventilation symptoms See if it could be obesity hypoventilation Find OTC relief for obesity hypoventilation symptoms Find doctors for obesity hypoventilation syndrome Learn medically proven home remedies for obesity hypoventilation Understand if obesity hypoventilation needs urgent care

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Explanation

Obesity Hypoventilation Syndrome (OHS) happens when extra body weight affects breathing. This condition makes it difficult for people to breathe deeply enough, especially at night, causing low oxygen and high carbon dioxide in the blood.

Key Points about OHS:

Causes:
- Being very overweight puts pressure on the chest, making it hard for the lungs to expand fully.
- This leads to shallow breathing and not enough air getting in and out of the lungs.
Symptoms:
- People with OHS often feel very tired during the day.
- They might have trouble focusing and may even fall asleep during activities.
- If you're experiencing concerning symptoms like excessive daytime fatigue or breathing difficulties, take our free AI symptom checker to better understand what might be causing them.
Risks:
- OHS can lead to serious health problems like heart issues and high blood pressure if not treated.
Treatment:
- Losing weight can help improve breathing.
- Special breathing machines at night can also help people with OHS breathe better.

Understanding and managing OHS is important to improve health and quality of life.

(References)

Masa JF, Pépin JL, Borel JC, Mokhlesi B, Murphy PB, & Sánchez-Quiroga MÁ. (2019). Obesity hypoventilation syndrome. European respiratory review : an official journal of the European Respiratory Society, 30872398.
Chau EH, Lam D, Wong J, Mokhlesi B, & Chung F. (2012). Obesity hypoventilation syndrome: a review of .... Anesthesiology, 22614131.
Mokhlesi B. (2010). Obesity hypoventilation syndrome: a state-of-the-art review. Respiratory care, 20875161.

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