What is hypercapnia?

Hypercapnia, or hypercarbia, is when you have too much carbon dioxide (CO2) in your bloodstream. It usually happens as a result of hypoventilation, or not being able to breathe properly and get oxygen into your lungs. When your body isn’t getting enough fresh oxygen or getting rid of CO2, you might need to gasp or suddenly inhale a lot of air to balance your levels of oxygen and CO2.

This isn’t always a cause for concern. For example, if your breathing is shallow when you’re sleeping deeply, your body instinctively reacts. You may turn in your bed or wake up suddenly. Your body can then resume normal breathing and get more oxygen into the blood.

Hypercapnia can also be a symptom of underlying conditions that affect your breathing and your blood.

Keep reading to learn more about the symptoms, causes, and more.

Symptoms of hypercapnia can sometimes be mild. Your body can quickly correct these symptoms to breathe better and balance your CO2 levels.

Mild symptoms of hypercapnia include:

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

If these symptoms persist beyond a few days, see your doctor. They can determine whether you’re experiencing hypercapnia or another underlying condition.

Severe symptoms

Severe hypercapnia can pose more of a threat. It can prevent you from breathing properly. Unlike with mild hypercapnia, your body can’t correct severe symptoms quickly. It can be extremely harmful or fatal if your respiratory system shuts down.

See your doctor right away if you have one or more of the following symptoms, especially if you’ve been diagnosed with chronic obstructive pulmonary disease (COPD):

  • unexplained feelings of confusion
  • abnormal feelings of paranoia or depression
  • abnormal muscle twitching
  • irregular heartbeat
  • hyperventilation
  • seizures
  • panic attack
  • passing out

COPD is a term for conditions that make it harder for you to breathe. Chronic bronchitis and emphysema are two common examples of COPD.

COPD is often caused by smoking or breathing in 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 air sacs. When this happens, your lungs can’t take in oxygen effectively.

COPD can also cause your trachea (windpipe) and the airways that lead to your alveoli, called bronchioles, to become inflamed. These parts may also produce a lot of extra mucus, making breathing even harder. The blockage and inflammation impede air flow in and out of the lungs. As a result, your body can’t get rid of CO2. This can cause CO2 to build up in your bloodstream.

Not everyone with COPD will get hypercapnia. But as COPD progresses, you’re more likely to have an imbalance of oxygen and CO2 in your body due to improper breathing.

Hypercapnia can have many other causes besides COPD, too. For example:

  • Sleep apnea prevents you from breathing properly while you sleep. This can keep you from getting oxygen into your blood.
  • Being overweight or obese can also keep you from getting enough air due to the pressure put on your lungs by your weight.
  • Activities that may limit you from breathing in fresh air, such as scuba diving or being on a ventilator during anesthesia, can also cause hypercapnia.
  • Physical illness or events that cause your body to produce more CO2, such as having a fever or eating a lot of carbs, can both increase the amount of CO2 in your bloodstream.

Gas exchange problems

Some underlying conditions can cause dead space in your body. This means that not all of the air you breathe in actually takes part in your breathing process. When this happens, it’s usually because a part of your respiratory system isn’t working properly. In many cases, this involves your lungs not doing their part in gas exchange.

Gas exchange is the process by which oxygen enters your blood and CO2 leaves your body. Problems can be caused by conditions like pulmonary embolus and emphysema.

Nerve and muscular problems

Nerve and muscular conditions can also cause hypercapnia. In some conditions, the nerves and muscles that help you breathe may not work properly. These can include Guillain-Barré syndrome, an immune system condition that weakens your nerves and muscles. This condition can affect your ability to get enough oxygen and can lead to too much CO2 in your bloodstream. Muscular dystrophies, or conditions that cause your muscles to weaken over time, can also make it hard to breathe and get enough oxygen.

Genetic causes

In rare cases, hypercapnia can be caused 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.

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

  • smoking cigarettes, cigars, or pipes heavily
  • 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 also 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 that 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 and make sure your oxygen pressure is normal.

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.

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 that you stop smoking or limit your exposure to fumes or chemicals if they’ve caused COPD-related hypercapnia.


If you have to go to your doctor’s office or the hospital 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 that’s causing you not to get enough oxygen through normal breathing or if you’ve experienced respiratory failure and can’t breathe very well on your own.


Some medications can help you breathe better, including:

  • bronchodilators, which help your airway muscles work properly
  • inhaled or oral corticosteroids, which help keep airway inflammation to a minimum
  • antibiotics for respiratory infections, such as pneumonia or acute bronchitis


Some therapies can also help treat symptoms and causes of hypercapnia. For example, with oxygen therapy, you carry a small device around that delivers oxygen straight into your lungs. 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 a lung volume reduction surgery, your doctor removes damaged tissue to make room for your remaining healthy tissue to expand and bring in more oxygen. In a lung transplant, an unhealthy lung is removed and replaced by a healthy lung from an organ donor.

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

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

If you need long-term treatment or surgery, make sure you listen closely to your doctor’s instructions so that 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.

In many cases, you can still live a healthy, active life even if you’ve experienced hypercapnia.

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

Making lifestyle changes, such as quitting smoking, losing weight, or exercising regularly, can also reduce your risk of hypercapnia significantly.