Cough overview and Definition

 A cough is way of responding when something irritates or triggers the throat and respiratory tract.




The three main receptors plays a vital role in the cough:

  • Rapidly adapting receptors (RARs) that respond to mechanical stimuli, cigarette smoke, ammonia, acidic and alkaline solutions, hypotonic and hypertonic saline, pulmonary congestion, atelectasis, and bronchoconstriction
  • Slowly adapting receptors (SARs)
  • Nociceptors on C-fibers that respond to chemical stimuli as well as inflammatory and immunological mediators such as histamine, bradykinin, prostaglandins, substance P, capsaicin, and acidic pH


It is believed that the cough is caused by the following mechanism due to hypersensitivity reactions:


Cough is described as an chronic infection which shows inflammation in the pulmonary airway and

bronchial hyperresponsiveness to an allergen. Inflammatory cells are

accumulated in respiratory bronchioles.

Physiologically, allergen inhaled results in provocation of the inflammatory system of the respiratory

system resulting in increased secreation of inflammatory mediators such as methacalmine and

histamine. Release of histamine from the mast cells results in activation of the prostaglandins and

leukotrienes.In addition to that cytokines are also released from the mast cells which leads to

Increased vascular permeability, mucus secretion, bronchospasm, and wheezing. These leads to the bronchoconstriction and the airway is disturbed which results in cough mechanisms.

Triggering factors that results in blockage of the pulmonary airway include cold air, exercise, viral upper

respiratory infection, cigarette smoke, and respiratory allergens. Bronchial provocation with allergen

induces a prompt early phase immunoglobulin E (IgE)-mediated decrease in bronchial airflow. Initially

there is an increase in the leukocyte count in the pulmonary ares with help of CD4+ cells. The activated

T-lymphocytes also direct the release of inflammatory mediators from eosinophils, mast cells, and

lymphocytes. The cross-linkage of two IgE molecules by allergen causes mast cells to degranulate,

releasing histamine, leukotrienes, and other mediators that perpetuate the airway inflammation.

Histolopathology of the bronchial airway might shows an inflammatory infiltrate consisting

of eosinophils , mast cells, lymphocytes, monocytes, and neutrophils.

Clinical signs & symptoms

Difficulty in breathing

Wheezing cough


Rapid breathing

Difficulty in speech

Pressure on the chest

Differential Diagnosis

It is the most common cause of the chronic cough .  avoding environmental irritants and offending antigens, treating sinusitis with antibitics and wearing patients off nasal dcongstants for rhinitis medications. The treatment is with thedecongestants and antihistamines.


Asthma is a chronic condition of the respiratory system in which the airways get blocked and narrowed.the airways get swollen and may produce excess mucus resulting in breathing difficulties and couhing.Nonallergic eosinophilic bronchitis. The asthmatic symptoms include Difficulty in breathing

Wheezing, cough,Sneezing,Rapid breathing,Difficulty in speech,Pressure on the chest

Gastroesophageal reflux disease

Gastroesophageal reflux disorder indicates regurgitation of the acidic content into the esophagus due to the dysfuction of the valve present between the oesophagus and stomach.

The choice of acid suppressive medication can include histamine 2 (H2) blockers, proton pump inhibitors (PPIs), and prokinetic agents.

indicated that treatment of refractory chronic cough with a combination of speech pathology therapy and pregabalin (300 mg daily) is more effective than treatment with speech pathology therapy plus placebo.


The prognosis is excellent.


The triggering factors should be kept in control.

the patient should avoid allerens which are lifethreatening to them.

Allergens include smoke,non selective beta blockers,sulfite containing foods and smoking and second hand smokers also called as passive smokers are the reasons for deterioration in the treatment. 

Yoga provide the better relief.

Obesity should be avoided.

If GERD is suspected then proper treatment should be checked.