A barking cough is a distinct, harsh, or brassy sound often compared to the call of a seal. While commonly associated with childhood croup, its presence in an adult requires prompt attention. The characteristic sound is produced when air is forcefully expelled through a narrowed upper airway, specifically the larynx (voice box) or the trachea (windpipe). This narrowing is caused by swelling, infection, or a long-term structural or neurological issue affecting the vocal cords.
Acute Inflammation of the Upper Airway
The most frequent causes of a barking cough in adults involve acute inflammatory conditions that cause rapid swelling in the voice box. Laryngitis is a common culprit, typically triggered by viral infections like parainfluenza, influenza, or the common cold viruses. The inflammation causes the vocal cords to become swollen, distorting the sound of the cough and often leading to hoarseness or voice loss.
When the inflammation extends down into the windpipe, the condition is known as tracheitis, which further narrows the airway and exacerbates the cough. A more severe, though rare, presentation is adult-onset laryngotracheobronchitis, commonly known as croup. This condition involves swelling that affects the subglottic region just below the vocal cords.
Along with the barking cough, patients may experience fever, a sore throat, and stridor, which is a high-pitched, whistling sound heard when breathing in. While most cases are viral, bacterial tracheitis is a serious secondary infection that can develop and requires immediate medical intervention.
Specific Highly Contagious Infections
One of the most concerning causes of a severe, barking-like cough is the highly contagious bacterial infection Pertussis. This disease is caused by the bacterium Bordetella pertussis. The illness progresses through three main stages, beginning with the catarrhal stage, which mimics a common cold with mild cough and runny nose.
The cough intensifies during the paroxysmal stage, typically one to two weeks into the infection, manifesting as long, violent, uncontrolled fits. In adults, these episodes of repetitive coughing often lack the classic “whoop” sound that defines the disease in children. Instead, the cough is persistent, severe, and may lead to vomiting or exhaustion immediately afterward.
This severe, prolonged cough can sometimes be interpreted as having a brassy or barking quality due to the sheer force and irritation to the larynx. The paroxysmal stage can last for six weeks or longer, earning Pertussis the nickname “the 100-day cough.” Diagnosis is important because the infection is extremely contagious, and antibiotics can help reduce contagiousness, though they are less effective at shortening the cough once the paroxysmal stage has begun.
Chronic Anatomical and Neurological Factors
When a barking or brassy cough persists for eight weeks or more, the cause often shifts from an acute infection to a chronic structural or neurological problem. A common diagnosis in this category is Vocal Cord Dysfunction (VCD), also known as paradoxical vocal cord movement. This condition involves the vocal cords closing involuntarily when a person inhales, rather than opening, which obstructs airflow and triggers a forceful, barking-like cough.
Structural irritation can also lead to a persistent cough, such as that caused by severe, uncontrolled Gastroesophageal Reflux Disease (GERD) or Laryngopharyngeal Reflux (LPR). Stomach acid travels up the esophagus to irritate the sensitive tissues of the larynx, causing chronic inflammation and a cough that is often worse at night. Less common, but more serious, structural causes include benign or malignant laryngeal tumors that physically interfere with vocal cord movement and air passage.
Neurological factors play a role when there is hypersensitivity or damage to the vagus nerve, which controls the larynx’s function. This vagal neuropathy can result in an exaggerated cough reflex, where even mild stimuli like talking, laughing, or cold air can trigger a severe episode. This chronic, neurogenic cough often presents with a persistent, dry, and sometimes brassy sound, signaling a disorder in the nerve pathways rather than just inflammation alone.