Evidence Based

Causes & Health Risks of Low Carbon Dioxide (CO2) Levels

Written by Mathew Eng, PharmD | Reviewed by Ana Aleksic, MSc (Pharmacy) | Last updated:
Medically reviewed by
Puya Yazdi, MD | Written by Mathew Eng, PharmD | Reviewed by Ana Aleksic, MSc (Pharmacy) | Last updated:

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Carbon dioxide risks

Carbon dioxide is in the air, in the ocean, and even in soda. In your body, carbon dioxide controls breathing and maintains the pH of your blood. Learn about the causes and dangers of low carbon dioxide levels, including anxiety and panic attacks.

Causes of Low Carbon Dioxide Levels

Most of the carbon dioxide (CO2) in your body is created as a byproduct by your cells when they convert sugars and fats into energy. This provides a steady source of CO2, which then leaves the body whenever you breathe out [1, 2].

It’s very rare for your metabolism to produce less CO2. Instead, the main reason for low CO2 levels is due to more CO2 leaving the body, usually through increased exhalation [1, 2].

Several different factors can increase the amount of CO2 that leaves your body. In the following sections, we’ll list out some major reasons for low CO2 levels and the effect that has on your health.

Metabolic Acidosis

Metabolic acidosis occurs when the pH of the blood becomes too acidic (pH < 7.35). This can happen when the body produces too much acid, when the kidneys are not removing enough acid from the body, or when the body loses too much HCO3- [3, 4].

For example, poorly-controlled diabetes can cause a buildup of ketones, an acidic compound that lowers blood pH.

Lactic acid buildup, caused by several disorders like heart and liver failure, can also lead to acidosis. Fermented foods also contain lactic acid. There is one case report of kombucha, a fermented tea, causing lactic acidosis after a man drank a 1 liter bottle [3, 4, 5].

Your diet can also impact your acid-base balance. Certain foods can release acids into the bloodstream, causing a mild form of metabolic acidosis. Some examples of acidic foods include meats (beef, pork, and poultry), eggs, and beans [6].

Other causes include severe vomiting or diarrhea, which can deplete the body of HCO3-. Also if the kidneys are damaged, they may not be able to filter out acids from the blood, which increases the acidity of the blood [3, 4].

Symptoms of metabolic acidosis vary greatly depending on the underlying cause and may include headache, confusion, anxiety, and coma [3, 4].

Diabetes, food poisoning, and eating a lot of meat or foods high in lactic acid can lower your carbon dioxide levels.

How does low HCO3- decrease CO2?

When the blood is acidic and HCO3- levels are low, your body’s natural response is to increase your breathing rate. By breathing faster, you exhale more CO2 out of your body, which decreases your CO2 blood levels and helps bring your blood pH back to normal [3, 4].

When your blood pH becomes too acidic, your body’s natural response is to breathe faster causing more CO2 to be exhaled out.

Respiratory Alkalosis

Respiratory alkalosis occurs when you breathe too rapidly (hyperventilation), causing you to expel more CO2 out of your body. This lowers CO2 levels and increases blood pH. Hyperventilation may be caused by many different factors, such as stress, anxiety, fever, and lung disorders [7].

Some symptoms of respiratory alkalosis include irregular heart rhythm, sweating, and convulsions [7].

For more information, check out this article on respiratory alkalosis.


Many different medications can potentially decrease CO2 levels, typically by either increasing the concentration of acids or decreasing the level of HCO2- in the blood. Some examples include [8]:

  • Acetazolamide, used to treat glaucoma, altitude sickness, and epilepsy
  • Sulfonamides, a group of antibiotics
  • Cholestyramine, used to high cholesterol
  • Metformin, used to treat diabetes
  • Aspirin (in excess)
  • ACEIs and ARBs, two classes of medications used to treat high blood pressure

Negative Effects of Low CO2 Levels

So far we have discussed how low CO2 levels can alter the pH and oxygen balance in the blood, leading to negative health effects and symptoms. But research shows that chronically low CO2 levels may have additional harmful consequences to your health.

1) Greater Risk of Dying

Multiple studies have discovered that low bicarbonate levels can increase your risk of death. One study of over 31,000 adults found that those with HCO3- levels less than 26 mEq/L are about 1.5 times more likely to die from any cause compared to those with levels above 31 mEq/L [9].

It’s worse for people with chronic kidney disease (CKD). Based on a study of almost 16,000 adults with CKD, people with HCO3- levels below 22 mEq/L are 2.6 times more likely to die compared to people with levels above 31 mEq/L [10].

Low carbon dioxide levels may increase your risk of dying from any cause, especially if you have kidney disease.

2) Worse Asthma Symptoms

Low CO2 levels can trigger several changes in the lungs, such as narrowing of the airways, otherwise known as bronchoconstriction. These effects on the lungs can negatively impact health, especially those with asthma [11].

Research shows that lower CO2 levels can reduce lung function, worsen asthma symptoms, and lower quality of life in asthma patients [11].

Low carbon dioxide levels can further narrow the airways and worsen asthma.

3) Connections to Anxiety and Panic Disorder

Hyperventilation often goes hand in hand with anxiety and panic attacks. There is evidence that CO2 levels in the blood also may play an important role [11].

For example, studies show that baseline CO2 levels in people with panic disorder and PTSD are lower compared to the general population. Some researchers theorize that this lower baseline CO2 level is a natural coping mechanism of the body since sudden increases in CO2 are known to trigger panic attacks [11].

When you go through a panic attack and hyperventilate, your carbon dioxide levels drop.

4) Reduces Blood Flow in the Brain

CO2 levels and blood pH can change how narrow or wide your blood vessels are, especially in the brain. Depending on the blood pH, a low CO2 level decreases the pressure of the cerebrospinal fluid (a clear fluid found in the brain and spine) as well as the flow of blood in the brain [12].

This change in cerebrospinal fluid and brain blood flow can interfere with brain imaging results, possibly leading to a misdiagnosis. Poor brain blood flow is also linked with cognitive problems and “brain fog” [13, 14].

Low carbon dioxide levels may reduce blood in the brain, which may impair cognition.

Ways to Improve Carbon Dioxide Levels

Lifestyle & Dietary Changes

If your CO2 levels are too low, the first step your doctor will take is treating the underlying condition that is causing the imbalance. This could mean anything from treating possible kidney or lung issues to stopping certain medications [2].

But there are some simple steps you can take yourself to help improve your CO2 levels.

For low CO2 levels:

  • Drink plenty of water, dehydration is a common cause of metabolic acidosis [15]
  • Limit your alcohol consumption, drinking too much leads to metabolic acidosis [16]
  • Keep your diabetes well controlled, find out how in our glucose article [17]
  • Eat less acidic foods (meat, eggs, beans, fermented foods) and more basic foods (fruits and vegetables) [6]
  • Breathing exercises (like yoga breathing, Buteyko breathing) and relaxation techniques may help with hyperventilation if you have anxiety [18, 19]

Learn More

This post is part of a three-part series about carbon dioxide. Read the other parts to learn about:

Irregular CO2 Levels?

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When you breathe out, you naturally lose some CO2. However, if you hyperventilate, you begin exhaling more CO2 than you produce, which lowers your CO2 levels.

Diseases and diet that lower your blood pH, conditions that trigger hyperventilation, and certain medications can all result in low CO2.

Low CO2 levels are associated with panic disorders, worse asthma symptoms, and even a greater risk of dying.

About the Author

Mathew Eng

Mathew received his PharmD from the University of Hawaii and an undergraduate degree in Biology from the University of Washington.
Mathew is a licensed pharmacist with clinical experience in oncology, infectious disease, and diabetes management. He has a passion for personalized patient care and believes that education is essential to living a healthy life. His goal is to motivate individuals to find ways to manage their chronic conditions.

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