A Guide to Respiratory Alkalosis

Medically Reviewed By Luke Davis, MD
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Respiratory alkalosis happens when the blood is too alkaline. It results from the lungs getting rid of too much carbon dioxide through increased breathing. There are acute and chronic forms of respiratory alkalosis. Chronic respiratory alkalosis typically has no symptoms. Respiratory alkalosis treatment involves addressing the underlying cause.

This article explains respiratory alkalosis, including the symptoms, treatment, and prevention.

What is respiratory alkalosis?

Person using an oxygen mask outdoors
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Alkalosis is a blood pH above the ideal range of 7.35–7.45. A high pH means the blood is too basic. When the alkalosis is respiratory, the lungs are responsible for the problem. Respiratory alkalosis is the most common acid-based disorder.

The lungs are one of the two key organs that regulate acid-base balance in the body — the kidneys are the other. 

The role of the lungs is to exhale carbon dioxide. Carbon dioxide is a byproduct of the breakdown, or metabolism, of fats and carbohydrates. Your body constantly releases carbon dioxide into the blood.

There, it combines to form carbonic acid. The body uses this relationship between carbon dioxide and carbonic acid as a buffering system to prevent rapid changes in the acid-base balance in the body.

The kidneys excrete or reabsorb bicarbonate, neutralizing carbon dioxide and carbonic acid.

The lungs and kidneys work together to balance the amount of carbonic acid in the blood.

The lungs increase or decrease breathing in response to blood pH. Getting rid of carbon dioxide will balance the acidity. Reducing the amount of exhaled carbon dioxide will balance alkalinity. 

However, in respiratory alkalosis, there is a problem with this balance. The lungs breathe out too much carbon dioxide through hyperventilation. Carbon dioxide levels in the blood fall too low. The blood becomes basic due to an imbalance between carbon dioxide and bicarbonate.

The kidneys will start getting rid of bicarbonate to compensate for respiratory alkalosis. However, this adjustment takes a few days.

What are the types of respiratory alkalosis?

There are two forms of respiratory alkalosis. Doctors can tell the difference between the two based on the blood pH level and how much the bicarbonate has changed from the patient’s usual level.

Acute respiratory alkalosis

Acute respiratory alkalosis is the immediate phase. The rapid loss of carbon dioxide leaves bicarbonate without a balance. Since the kidneys need time to adjust, pH levels will be elevated, and bicarbonate levels will be normal or lower than normal. 

Chronic respiratory alkalosis

Chronic respiratory alkalosis occurs after a few days. The level of carbon dioxide remains low. However, the kidneys have had time to adjust the amount of bicarbonate and get rid of it. So, pH will be normal or minimally elevated, and bicarbonate levels will be lower than normal.

What are the signs and symptoms of respiratory alkalosis?

The signs and symptoms of respiratory alkalosis depend on whether it is acute or chronic. The chronic form usually has no symptoms.

People with acute respiratory alkalosis will have some degree of hyperventilation. They often complain of shortness of breath or fast breathing.

Other symptoms may include:

Respiratory alkalosis can be a sign of a serious underlying condition. These symptoms should be promptly evaluated by a medical professional.

There can be many other symptoms that vary with the underlying cause. 

What causes respiratory alkalosis?

Hyperventilation is the basis of all causes of respiratory alkalosis. Diseases, disorders, and conditions resulting in respiratory alkalosis include the following.

Central nervous system conditions

Central nervous system conditions that can cause respiratory alkalosis include:


Medications that can cause respiratory alkalosis include:

  • medroxyprogesterone
  • progestins
  • salicylates

Metabolic disturbances

Metabolic disturbances and conditions that increase metabolic demand:

Hormones that are not metabolized by a diseased liver can lead to liver disease hyperventilation. This can cause respiratory alkalosis.

Pulmonary disorders

Pulmonary disorders that can cause respiratory alkalosis include:

Other causes

Being at a high altitude can cause respiratory alkalosis through hyperventilation to maintain an appropriate oxygen level in the blood.

Other causes can include pain, stress, anxiety, and certain toxins.

What are the risk factors for respiratory alkalosis?

The risk factors for developing respiratory alkalosis depend on the underlying cause.

How do you diagnose respiratory alkalosis?

To diagnose respiratory alkalosis, doctors will review your medical history and perform an exam. However, blood tests are necessary to make the diagnosis. These include:

  • arterial blood gas (ABG), which will show a decreased carbon dioxide level (PCO2) of less than 38 millimeters of mercury (mmHg) and a pH greater than 7.45
  • basic metabolic panel with electrolytes, including bicarbonate, sodium, potassium, calcium, phosphate, and magnesium

Doctors classify alkalosis as acute or chronic using pH levels and bicarbonate levels.

  • In acute respiratory alkalosis: The pH level will be elevated and bicarbonate levels will be normal or lower than normal.
  • In chronic respiratory alkalosis: The pH level will be normal or minimally elevated and bicarbonate levels will be lower than normal.

Doctors will also order testing to diagnose the underlying condition. These tests will vary.

What is the treatment for respiratory alkalosis?

Treating respiratory alkalosis depends entirely on the underlying cause.

What are the potential complications of respiratory alkalosis?

Respiratory alkalosis is not a life threatening condition. However, the underlying cause can be. The potential complications are entirely dependent on the cause. 

Frequently asked questions

Here are some other questions people often ask about respiratory alkalosis.

What is the most common cause of respiratory alkalosis?

In all cases, respiratory alkalosis is the result of hyperventilation. There are various reasons hyperventilation occurs. 

What is the difference between respiratory acidosis and respiratory alkalosis?

Respiratory acidosis is the opposite of respiratory alkalosis. In respiratory acidosis, the carbon dioxide concentration rises above its usual value, and the blood pH falls below 7.35. It occurs when inadequate breathing leads to a buildup of carbon dioxide. In respiratory alkalosis, the carbon dioxide concentration falls below its usual value, and the blood pH exceeds 7.45. It occurs when hyperventilation depletes carbon dioxide. 

How serious is respiratory alkalosis?

Respiratory alkalosis is not life threatening. However, the things that cause it can be. The seriousness of the situation will depend on the underlying cause.

How do you know you have respiratory alkalosis?

Finding out if you have respiratory alkalosis requires blood tests. Specifically, doctors need to look at arterial blood gases and may consider serum electrolytes. The latter is not required for a diagnosis.


Respiratory alkalosis is the result of hyperventilation, which depletes carbon dioxide. This raises the pH of the blood and creates an imbalance with bicarbonate.

If functioning normally, the kidneys correct the bicarbonate imbalance within a few days. However, the pH can remain high. While respiratory alkalosis is not life threatening, the underlying causes of respiratory alkalosis can be serious. Treatment aims to treat the cause. Correction of the blood pH is not necessary.

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Medical Reviewer: Luke Davis, MD
Last Review Date: 2022 Sep 16
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