Hypercapnia, also called hypercarbia, arises from having too much carbon dioxide in the blood. It typically happens with hypoxia, which is when there is not enough oxygen in the body.

Hypercapnia happens when breathing problems make it difficult to take in oxygen and breathe out carbon dioxide. It is typically due to a disease that affects the lungs.

Symptoms can range from mild to severe, and can include fatigue, headache, and confusion. Possible causes include the respiratory conditions chronic obstructive pulmonary disease (COPD) and asthma.

This article discusses symptoms and causes of hypercapnia and outlines some treatment options.

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Symptoms can be acute, meaning they start suddenly and last a short while. Or they can be chronic, meaning they last a long time. People with chronic hypercapnia may also experience a temporary worsening of symptoms.

Symptoms can range from mild to severe.

Mild symptoms

A person with hypercapnia might notice:

These symptoms may arise from shorter periods of shallow or slow breathing, such as during deep sleep.

The body can often balance carbon dioxide levels in the bloodstream and correct the symptoms by itself. However, if symptoms persist, a person should contact a doctor.

Severe symptoms

The symptoms of severe hypercapnia require immediate medical attention, as they can cause long-term complications. Some may even be fatal.

Severe hypercapnia symptoms include:

A person may also experience other symptoms related to an underlying disease such as COPD or asthma.

Here are some possible causes of hypercapnia.


COPD is an umbrella term for several conditions that affect breathing. Common forms of COPD include chronic bronchitis and emphysema.

Chronic bronchitis leads to inflammation and mucus in the airways, while emphysema involves damage to the alveoli (air sacs) in the lungs.

Both conditions can cause increased levels of carbon dioxide in the bloodstream.

The main cause of COPD is long-term exposure to lung irritants. According to the National Heart, Lung, and Blood Institute, cigarette smoke is the most common lung irritant that causes COPD in the United States.

However, up to 30% of people with COPD have never smoked. Some have a genetic condition in which the liver does not produce enough alpha-1-antitrypsin (AAT). AAT is a protein that supports lung health. Having an AAT deficiency is a risk factor for COPD development.

Air pollution and exposure to chemicals or dust may also cause COPD.

Although not everyone with COPD will develop hypercapnia, a person’s risk increases as their COPD progresses.

Which breathing exercises can help with COPD?


Asthma causes the airways to become inflamed and narrowed. It may impact breathing and the levels of carbon dioxide in the body when it is unmanaged.

People with asthma have a higher risk of hypercapnia.

Doctors do not know precisely why asthma develops, though it is likely due to a combination of genetic and environmental factors. Activities that can trigger an asthma attack include exercise and exposure to irritants, including cigarette smoke and air pollution.

How can yoga help manage asthma?

Sleep apnea

Sleep apnea can present as shallow breathing or pauses in breathing during sleep. It can affect oxygen levels in the blood and the body’s balance of carbon dioxide and oxygen.

Sleep apnea symptoms include:

Can surgery help with sleep apnea?

Nerve disorders and muscular problems

In some people, the nerves and muscles necessary for sufficient lung function may not work correctly. For example, muscular dystrophy can cause the muscles to weaken, eventually leading to breathing problems.

Other disorders of the nervous or muscular systems that can contribute to hypercapnia include the following:

Other causes

Other causes of high blood levels of carbon dioxide include:

Does wearing a face mask cause hypercapnia?

During the COVID-19 pandemic, some people had concerns that wearing a face mask could lead to hypercapnia. However, there is very little evidence to support this.

Face masks are not airtight. The materials allow air, including carbon dioxide, to circulate rather than build up. Even with medical-grade masks, it is unlikely that significant levels will build up with short-term use.

Additionally, thinner surgical and cloth masks are more porous and loose-fitting, allowing for even more air exchange.

People who have difficulty breathing do not need to wear a face mask.

Some tests used to diagnose hypercapnia include:

The treatment for hypercapnia will depend on the severity of the condition and the underlying cause. Options include:


Ventilation is typically the first line of treatment for hypercapnia. A doctor may use:

  • Noninvasive ventilation: Airflow comes through a mouthpiece or nasal mask. This is helpful for people with sleep apnea to keep their airways open at night. It is also known as continuous positive airway pressure, or CPAP.
  • Mechanical ventilation: A doctor will insert a tube through the mouth into the airway. This is called intubation.

People with severe hypercapnia symptoms may need a ventilation device to help them breathe.


Certain medications can help manage breathing or address underlying problems:

Oxygen therapy

People who undergo oxygen therapy regularly use a device to deliver oxygen to the lungs. Oxygen therapy can help balance the levels of carbon dioxide in the blood.

Lifestyle changes

To reduce symptoms and avoid complications, a doctor may recommend:


Some people with lung or airway damage need surgery. Lung volume reduction surgery can remove damaged tissue. With lung transplantation, a surgeon replaces a damaged lung with a healthy lung from a donor.

Methods for helping to prevent hypercapnia include:

  • treating existing lung conditions
  • quitting or avoiding smoking
  • reaching or maintaining a moderate weight
  • following an exercise plan
  • avoiding exposure to toxic fumes and chemicals

Here are some answers to questions people often ask about hypercapnia.

What is hypercapnia?

Hypercapnia, also called hypercarbia, is when there is too much carbon dioxide in the blood. It happens when not enough carbon dioxide leaves the lungs. Typically, at the same time, there is not enough oxygen entering the lungs.

What causes hypercapnia?

Health conditions that affect breathing, such as COPD and asthma, can cause it. Other factors include using a ventilator, diving, and having a neurological condition that affects breathing. Exposure to tobacco smoke increases the risk of conditions that lead to hypercapnia.

Is hypercarbia the same as hypercapnia?

Yes, people use these terms interchangeably. They both refer to a condition in which there is too much carbon dioxide in the blood. If this situation persists for a long time, or there is significant cardiopulmonary disease, there will not be enough oxygen in the blood. This is called hypoxemia.

Hypercapnia is when there is too much carbon dioxide in the blood. Addressing the underlying cause is key to managing symptoms and improving a person’s quality of life.

Anyone who has symptoms that may indicate hypercapnia should consult a doctor. The symptoms may be a sign of an underlying condition that needs treatment.