Hypercapnia, also known as hypercarbia, is a condition that occurs when a person has too much carbon dioxide (CO2) in their bloodstream. It can cause dizziness, fatigue, and shortness of breath.

Hypercapnia can be caused by various underlying respiratory conditions, such as chronic obstructive pulmonary disease (COPD), which may prevent a person’s lungs from either taking in enough oxygen or expelling (breathing out) enough CO2.

In mild hypercapnia, the body can often regulate itself, temporarily altering breathing by gasping or taking deeper breaths. Chronic cases, however, usually require medical intervention.

Consistently increased levels of CO2 in the bloodstream can be harmful over time, increasing the pH of your blood and affecting the health of the lungs, respiratory system, and other major systems in the body.

Symptoms of hypercapnia can vary in severity and depend on the underlying issue.

Mild symptoms of hypercapnia commonly include:

  • flushed skin
  • drowsiness or inability to focus
  • mild headaches
  • feeling disoriented or dizzy
  • shortness of breath
  • being abnormally tired or exhausted

If these symptoms persist beyond a few days, see your doctor.

Severe symptoms

The symptoms of severe hypercapnia can be life threatening and require immediate medical attention. See your doctor right away if you have one or more of the following symptoms, especially if you have COPD.

Hypercapnia can have several causes, including:

COPD is a term describing a group of progressive lung conditions that make it harder to breathe. Chronic bronchitis and emphysema are two common examples of COPD.

COPD is often caused by smoking or breathing harmful air in polluted environments. Over time, COPD causes the alveoli (air sacs) in your lungs to lose their ability to stretch as they take in oxygen.

COPD can also destroy the walls between these alveoli. This compromises the airflow in and out of the lungs, making it harder to take in oxygen and get rid of CO2.

Nerve and muscular problems

Nerve and muscular conditions that can lead to hypercapnia include:

Genetic causes

In rare cases, hypercapnia can be caused by a genetic condition in which your body doesn’t produce enough of a protein called alpha-1-antitrypsin. This protein comes from the liver and is used by your body to keep the lungs healthy.

Other causes for hypercapnia include:

Some risk factors for hypercapnia, especially as a result of COPD, include:

  • smoking cigarettes, cigars, or pipes
  • age, as many conditions that cause hypercapnia are progressive and usually don’t begin to show symptoms until after age 40
  • having asthma, especially if you smoke
  • breathing in fumes or chemicals in workplace environments, such as factories, warehouses, or electrical or chemical plants

A late diagnosis of COPD or another condition that causes hypercapnia can also increase your risk. See your doctor at least once per year for a full physical examination to make sure you’re keeping an eye on your overall health.

If your doctor thinks you have hypercapnia, they’ll likely test your blood and breathing to diagnose the issue and the underlying cause.

An arterial blood gas test is commonly used to diagnose hypercapnia. This test can assess the levels of oxygen and CO2 in your blood, determine your blood’s pH, and make sure your oxygen pressure is healthy.

Your doctor may also test your breathing using spirometry. In this test, you breathe forcefully into a tube. An attached spirometer measures how much air your lungs contain and how forcefully you can blow that air out.

X-rays or CT scans of your lungs can also help your doctor see if you have emphysema or other related lung conditions.

If an underlying condition is causing your hypercapnia, your doctor will set up a treatment plan for the symptoms of your condition.

Your doctor will likely recommend you stop smoking or limit your exposure to fumes or chemicals if they’ve caused COPD-related hypercapnia.


If you are hospitalized for severe symptoms, you may be put on a ventilator to make sure you can breathe properly. You may also be intubated, which is when a tube is inserted through your mouth into your airways to help you breathe.

These treatments allow you to get consistent oxygen to balance your CO2 levels. This is especially important if you have an underlying condition or if you’ve experienced respiratory failure and can’t breathe very well on your own.


Some medications can help you breathe better, including:


There are specific therapies that can help treat symptoms and causes of hypercapnia. For example, with oxygen therapy, you carry a small device that delivers oxygen straight into your lungs. Care must be taken because oxygen therapy is not for everyone. Supplemental oxygen for someone with COPD can sometimes make hypercapnia worse because it can cause an imbalance between the amount of oxygen entering the body compared to blood flow rates, a dangerous situation that could cause your red blood cells to release CO2 into your blood that your body can’t eliminate.

Pulmonary rehabilitation allows you to change your diet, exercise routine, and other habits to make sure that you’re contributing positively to your overall health. This can reduce your symptoms and the possible complications of an underlying condition.


Some cases may require surgery to treat or replace damaged airways or lungs.

In lung volume reduction surgery, your doctor removes damaged tissue to allow your remaining healthy tissue to expand and bring in more oxygen. In a lung transplant, a damaged lung is removed and replaced by a lung from an organ donor.

Both surgeries can be serious, so talk with your doctor about these options to see if they’re right for you.

If you have a respiratory condition causing hypercapnia, getting treatment is the best way to prevent hypercapnia.

Lifestyle measures, such as quitting smoking, losing weight, or exercising regularly, can also reduce your risk of hypercapnia significantly.

Getting treated for COPD or another underlying condition that can cause hypercapnia will significantly improve your long-term health and prevent future episodes.

If you need long-term treatment or surgery, listen closely to your doctor’s instructions so your treatment plan or recovery from surgery is successful. They’ll advise you on symptoms to look out for and what to do if they occur.

With proper care, people with hypercapnia can live healthy, active lives.

What happens when CO2 levels are too high?

When CO2 levels in the bloodstream are too high, it can lead to various symptoms, ranging from mild to potentially life threatening. Mild symptoms may include headaches, dizziness, and fatigue. In more severe cases, you may experience difficulty breathing, irregular heartbeat, seizures, or respiratory failure. Severe symptoms of hypercapnia require immediate medical attention.

What happens to the body during hypercapnia?

Hypercapnia occurs when oxygen and CO2 levels become imbalanced in the bloodstream. This imbalance changes the pH balance of your blood, making it too acidic. This condition is called metabolic acidosis. Metabolic acidosis can put excess strain on the kidneys, which can lead to kidney disease or failure.

What is the difference between hypercarbia, hypercapnia, and hypoxemia?

Hypercarbia and hypercapnia are terms describing conditions where there are excess amounts of CO2 in the bloodstream. While slight differences exist between the two conditions, their names are often used interchangeably.

Hypoxemia refers to having low oxygen levels in the bloodstream, which can cause harm to healthy tissues in the body. Hypercarbia, hypercapnia, and hypoxemia can co-occur but are not always related.

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