Sudden Severe Breathlessness Causes and Emergency Signs

Sudden and severe breathlessness is extremely distressing if it arises for no known reason and persists for even a few minutes. Breathlessness includes shortness of breath, difficulty breathing, labored breathing or discomfort when breathing that restricts the breathing rate and depth. While an acute shortness of breath is expected with sudden emotional stress or strenuous physical exertion, this rarely lasts for a prolonged period of time.

Emergency Signs and Symptoms

Sudden and severe breathless should be treated as a medical emergency if it is accompanied by :

  • Pallor (paleness of the skin) or cyanosis (bluish discoloration of the lips and skin)
  • Unexplained sweating
  • Chest pain
  • Dizziness and/or fainting spells
  • Abnormal breathing sounds

The presence of even one of these features along with the breathlessness should warrant the need for immediate medical attention. Even in the absence of these signs and symptoms, acute severe breathlessness should be investigated if it persists for more than a few minutes. Psychogenic causes may, however, present with no other signs and symptoms apart from breathless but there is usually a history of depression or anxiety or it is preceded by severe emotional stress.

Causes of Sudden and Severe Breathlessness

Acute Myocardial Infarction (Heart Attack)

An acute myocardial infarction arises when the blood supply to a portion of the heart muscle is suddenly interrupted resulting in cell death within the affected area. Other signs and symptoms that may accompany breathless includes :

  • Chest pain which radiates to the left arm, neck, jaw, upper abdomen and/or back
  • Sudden, excessive perspiration
  • Pallor
  • Dizziness and/or breathing

Pulmonary Edema (Fluid in Lungs)

There are several causes of pulmonary edema as discussed under fluid in the lungs. Sudden exacerbation of a pre-existing chronic condition or the onset of acute conditions like acute respiratory distress syndrome (ARDS) may cause sudden and severe breathlessness. It may also present with :

Obstructive Airway Diseases

This group of conditions includes asthma, emphysema and chronic bronchitis. Although these conditions are chronic in nature, an acute exacerbation may present with extreme breathlessness that is of a sudden onset. Patients, however, are usually aware of the underlying condition but still require immediate medical attention, especially if the emergency signs and symptoms described above are present.

With an acute exacerbation of asthma, the following features may also be present :

  • Wheeze
  • Rapid heart rate (tachycardia)
  • Diminished peak expiratory flow rate measured on a peak flow monitor
  • Cyanosis in the late stages

With an acute exacerbation of chronic obstructive pulmonary disease (emphysema or chronic bronchitis), the following signs and symptoms may also be present :

  • Pursed lips and nasal flaring
  • Cyanosis
  • Bounding pulse

Pulmonary Embolism

This occurs when the blood supply to the lung is suddenly interrupted by an embolus, usually a blood clot that dislodges from other sites like the legs. Prominent symptoms are more likely to arise with a major disruption and includes :

  • Sudden chest pain, similar to a heart attack
  • Cough, which may be bloody or blood-streaked (hemoptysis)
  • Wheezing
  • Swelling of the legs
  • Dizziness and/or fainting
  • Cold, clammy skin with central cyanosis


This is inflammation of the lung parenchyma, which may involve segments, lobes (lobar) and terminal bronchioles (bronchopneumonia). There are various causes of pneumonia as discussed under types of pneumonia but most cases are infectious in nature, particularly bacterial or viral. Presenting signs and symptoms include :

Metabolic Acidosis

This occurs when the acidity in the body fluids increases substantially due to increased acid production or diminished removal of acids from the body.  It may be seen with uncontrolled diabetes mellitus (sugar diabetes), kidney disease, the use of certain medication and toxicity like with antifreeze poisoning. Other signs and symptoms include :

  • Hyperventilation – rapid breathing and gasping
  • Unpleasant breath odor (also described as a sickening-fruity smell)
  • Lethargy with/without mental confusion
  • Signs of dehydration

Please note that any information or feedback on this website is not intended to replace a consultation with a health care professional and will not constitute a medical diagnosis. By using this website and the comment service you agree to abide by the comment terms and conditions as outlined on this page