What to do when allergies cause shortness of breath

In rare cases, an allergy can lead to a severe allergic reaction, called anaphylaxis or anaphylactic shock, which can be life threatening.

This affects the whole body and usually develops within minutes of exposure to something you’re allergic to.

Signs of anaphylaxis include any of the symptoms above, as well as:

Anaphylaxis is a medical emergency that requires immediate treatment.

Read more about anaphylaxis for information about what to do if it occurs.

Sheet final reviewed: 22 November 2018
Next review due: 22 November 2021

Shortness of breath
Other names Dyspnea, dyspnoea, breathlessness, difficulty of breathing, respiratory distress
  1. Dyspnea: /dɪspˈniːə/
Specialty Pulmonology

Shortness of breath (SOB), also known as dyspnea, is the feeling that one cannot breathe well enough.

The American Thoracic Society defines it as «a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity», and recommends evaluating dyspnea by assessing the intensity of the distinct sensations, the degree of distress involved, and its burden or impact on activities of daily living.

What to do when allergies cause shortness of breath

Distinct sensations include effort/work, chest tightness, and air hunger (the feeling of not enough oxygen).[1]

Dyspnea is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations[2] or light exertion. In 85% of cases it is due to asthma, pneumonia, cardiac ischemia, interstitial lung disease, congestive heart failure, chronic obstructive pulmonary disease, or psychogenic causes,[2][3] such as panic disorder and anxiety.[4] Treatment typically depends on the underlying cause.[5]


Grade Degree of dyspnea
0 no dyspnea except with strenuous exercise
1 dyspnea when walking up an incline or hurrying on the level
2 walks slower than most on the level, or stops after 15 minutes of walking on the level
3 stops after a few minutes of walking on the level
4 with minimal activity such as getting dressed, too dyspneic to leave the home

The initial approach to evaluation begins by assessment of the airway, breathing, and circulation followed by a medical history and physical examination.[2] Signs that represent significant severity include hypotension, hypoxemia, tracheal deviation, altered mental status, unstable dysrhythmia, stridor, intercostal indrawing, cyanosis, tripod positioning, pronounced use of accessory muscles (sternocleidomastoid, scalenes) and absent breath sounds.[11]

A number of scales may be used to quantify the degree of shortness of breath.[18] It may be subjectively rated on a scale from 1 to 10 with descriptors associated with the number (The Modified Borg Scale).[18] Alternatively a scale such as the MRC breathlessness scale might be used – it suggests five grades of dyspnea based on the circumstances in which it arises.[19]

Blood tests

A number of labs may be helpful in determining the cause of shortness of breath.

What to do when allergies cause shortness of breath

D-dimer, while useful to law out a pulmonary embolism in those who are at low risk, is not of much worth if it is positive, as it may be positive in a number of conditions that lead to shortness of breath.[13] A low level of brain natriuretic peptide is useful in ruling out congestive heart failure; however, a high level, while supportive of the diagnosis, could also be due to advanced age, kidney failure, acute coronary syndrome, or a large pulmonary embolism.[13]


A chest x-ray is useful to confirm or law out a pneumothorax, pulmonary edema, or pneumonia.[13] Spiral computed tomography with intravenous radiocontrast is the imaging study of choice to assess for pulmonary embolism.[13]


Different physiological pathways may lead to shortness of breath including via ASICchemoreceptors, mechanoreceptors, and lung receptors.[13]

It is thought that three main components contribute to dyspnea: afferent signals, efferent signals, and central information processing.

It is believed the central processing in the brain compares the afferent and efferent signals; and dyspnea results when a «mismatch» occurs between the two: such as when the need for ventilation (afferent signaling) is not being met by physical breathing (efferent signaling).[17]

Afferent signals are sensory neuronal signals that ascend to the brain. Afferent neurons significant in dyspnea arise from a large number of sources including the carotid bodies, medulla, lungs, and chest wall. Chemoreceptors in the carotid bodies and medulla supply information regarding the blood gas levels of O2, CO2 and H+.

What to do when allergies cause shortness of breath

In the lungs, juxtacapillary (J) receptors are sensitive to pulmonary interstitial edema, while stretch receptors signal bronchoconstriction. Muscle spindles in the chest wall signal the stretch and tension of the respiratory muscles. Thus, poor ventilation leading to hypercapnia, left heart failure leading to interstitial edema (impairing gas exchange), asthma causing bronchoconstriction (limiting airflow) and muscle fatigue leading to ineffective respiratory muscle action could every contribute to a feeling of dyspnea.[17]

Efferent signals are the motor neuronal signals descending to the respiratory muscles. The most significant respiratory muscle is the diaphragm.

Other respiratory muscles include the external and internal intercostal muscles, the abdominal muscles and the accessory breathing muscles.

As the brain receives its plentiful supply of afferent information relating to ventilation, it is capable to compare it to the current level of respiration as sure by the efferent signals.

What to do when allergies cause shortness of breath

If the level of respiration is inappropriate for the body’s status then dyspnea might happen. There is also a psychological component to dyspnea, as some people may become aware of their breathing in such circumstances but not experience the typical distress of dyspnea.[17]

Main allergy symptoms

Common symptoms of an allergic reaction include:

  1. itchy, red, watering eyes (conjunctivitis)
  2. sneezing and an itchy, runny or blocked nose (allergic rhinitis)
  3. swollen lips, tongue, eyes or face
  4. a raised, itchy, red rash (hives)
  5. wheezing, chest tightness, shortness of breath and a cough
  6. tummy pain, feeling ill, vomiting or diarrhoea
  7. dry, red and cracked skin

The symptoms vary depending on what you’re allergic to and how you come into contact with it.

For example, you may have a runny nose if exposed to pollen, develop a rash if you own a skin allergy, or feel sick if you eat something you’re allergic to.

See your GP if you or your kid might own had an allergic reaction to something. They can assist determine whether the symptoms are caused by an allergy or another condition.

What to do when allergies cause shortness of breath

Read more about diagnosing allergies.

Differential diagnosis

Further information: List of causes of shortness of breath

While shortness of breath is generally caused by disorders of the cardiac or respiratory system, other systems such as neurological,[10]musculoskeletal, endocrine, hematologic, and psychiatric may be the cause.[11]DiagnosisPro, an online medical expert system, listed 497 distinct causes in October 2010.[12] The most common cardiovascular causes are acute myocardial infarction and congestive heart failure while common pulmonary causes include chronic obstructive pulmonary disease, asthma, pneumothorax, pulmonary edema and pneumonia.[2] On a pathophysiological basis the causes can be divided into: (1) an increased awareness of normal breathing such as during an anxiety attack, (2) an increase in the work of breathing and (3) an abnormality in the ventilatory system.[10]

Congestive heart failure

Congestive heart failure frequently presents with shortness of breath with exertion, orthopnea, and paroxysmal nocturnal dyspnea.[2] It affects between 1–2% of the general United States population and occurs in 10% of those over 65 years old.[2][13] Risk factors for acute decompensation include high dietary salt intake, medication noncompliance, cardiac ischemia, abnormal heart rhythms, kidney failure, pulmonary emboli, hypertension, and infections.[13] Treatment efforts are directed towards decreasing lung congestion.[2]

Acute coronary syndrome

Acute coronary syndrome frequently presents with retrosternal chest discomfort and difficulty catching the breath.[2] It however may atypically present with shortness of breath alone.[13] Risk factors include ancient age, smoking, hypertension, hyperlipidemia, and diabetes.[13] An electrocardiogram and cardiac enzymes are significant both for diagnosis and directing treatment.[13] Treatment involves measures to decrease the oxygen requirement of the heart and efforts to increase blood flow.[2]


Main article: Pneumonia

The symptoms of pneumonia are fever, productive cough, shortness of breath, and pleuritic chest pain.[2] Inspiratory crackles may be heard on exam.[2] A chest x-ray can be useful to differentiate pneumonia from congestive heart failure.[2] As the cause is generally a bacterial infection, antibiotics are typically used for treatment.[2]

Severity and prognosis of pneumonia can be estimated from CURB65, where C=Confusion, U= Uremia (>7), R=Respiratory rate >30, B= BP<90, 65= Age>65.[citation needed]


Main article: Pneumothorax

Pneumothorax presents typically with pleuritic chest pain of acute onset and shortness of breath not improved with oxygen.[2] Physical findings may include absent breath sounds on one side of the chest, jugular venous distension, and tracheal deviation.[2]

Chronic obstructive pulmonary disease

People with chronic obstructive pulmonary disease (COPD), most commonly emphysema or chronic bronchitis, frequently own chronic shortness of breath and a chronic productive cough.[2] An acute exacerbation presents with increased shortness of breath and sputum production.[2]COPD is a risk factor for pneumonia; thus this condition should be ruled out.[2] In an acute exacerbation treatment is with a combination of anticholinergics, beta2-adrenoceptor agonists, steroids and possibly positive pressure ventilation.[2]


Asthma is the most common reason for presenting to the emergency room with shortness of breath.[2] It is the most common lung disease in both developing and developed countries affecting about 5% of the population.[2] Other symptoms include wheezing, tightness in the chest, and a non productive cough.[2] Inhaled corticosteroids are the preferred treatment for children, however these drugs can reduce the growth rate.[14] Acute symptoms are treated with short-acting bronchodilators.

Pulmonary embolism

Pulmonary embolism classically presents with an acute onset of shortness of breath.[2] Other presenting symptoms include pleuritic chest pain, cough, hemoptysis, and fever.[2] Risk factors include deep vein thrombosis, recent surgery, cancer, and previous thromboembolism.[2] It must always be considered in those with acute onset of shortness of breath owing to its high risk of mortality.[2] Diagnosis, however, may be difficult[2] and Wells Score is often used to assess the clinical probability.

Treatment, depending on severity of symptoms, typically starts with anticoagulants; the presence of ominous signs (low blood pressure) may warrant the use of thrombolytic drugs.[2]


Anemia that develops gradually generally presents with exertional dyspnea, fatigue, weakness, and tachycardia.[15] It may lead to heart failure.[15] Anaemia is often a cause of dyspnea.

What to do when allergies cause shortness of breath

Menstruation, particularly if excessive, can contribute to anaemia and to consequential dyspnea in women. Headaches are also a symptom of dyspnea in patients suffering from anaemia. Some patients report a numb sensation in their head, and others own reported blurred vision caused by hypotension behind the eye due to a lack of oxygen and pressure; these patients own also reported severe head pains, numerous of which lead to permanent brain damage.

What to do when allergies cause shortness of breath

Symptoms can include loss of concentration, focus, fatigue, language faculty impairment and memory loss.[citation needed]


Other significant or common causes of shortness of breath include cardiac tamponade, anaphylaxis, interstitial lung disease, panic attacks,[5][11][15] and pulmonary hypertension. Cardiac tamponade presents with dyspnea, tachycardia, elevated jugular venous pressure, and pulsus paradoxus.[15] The gold standard for diagnosis is ultrasound.[15] Anaphylaxis typically begins over a few minutes in a person with a previous history of the same.[5] Other symptoms include urticaria, throat swelling, and gastrointestinal upset.[5] The primary treatment is epinephrine.[5] Interstitial lung disease presents with gradual onset of shortness of breath typically with a history of a predisposing environmental exposure.[11] Shortness of breath is often the only symptom in those with tachydysrhythmias.[13] Panic attacks typically present with hyperventilation, sweating, and numbness.[5] They are however a diagnosis of exclusion.[11] Around 2/3 of women experience shortness of breath as a part of a normal pregnancy.[8] Neurological conditions such as spinal cord injury, phrenic nerve injuries, Guillain–Barré syndrome, amyotrophic lateral sclerosis, multiple sclerosis and muscular dystrophy can every cause an individual to experience shortness of breath.[10] Shortness of breath can also happen as a result of vocal cord dysfunction (VCD).[16]


The American Thoracic Society defines dyspnea as: «A subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity.»[6] Other definitions describe it as «difficulty in breathing»,[7] «disordered or inadequate breathing»,[8] «uncomfortable awareness of breathing»,[3] and as the experience of «breathlessness» (which may be either acute or chronic).[2][5][9]