A cough lasting more than 8 weeks in adults (or more than 4 weeks in children) is considered chronic or persistent. It is one of the most frequent reasons people visit a doctor. While most acute coughs are caused by viral respiratory infections and resolve within 2-3 weeks, a lingering cough that persists well beyond an illness has a distinct set of causes. The three most common causes in non-smokers, postnasal drip, GERD, and asthma, account for the majority of cases and are all treatable.

1. Upper Airway Cough Syndrome (Postnasal Drip)

What it is: The most common cause of chronic cough, mucus from the nose or sinuses dripping down the back of the throat irritates the cough receptors.

Why it happens: Allergic rhinitis, sinusitis, and non-allergic rhinitis can all produce excess mucus that flows into the back of the throat (postnasal drip), stimulating the cough reflex.

Common symptoms: Cough that is often worse at night and in the morning; sensation of mucus dripping down the back of the throat; throat clearing; runny or stuffy nose; may cause a sore throat from constant throat clearing.

Risk factors: Seasonal or perennial allergies, sinusitis, dry environments, recent upper respiratory infection.

When to seek evaluation: Antihistamines and nasal corticosteroid sprays are highly effective for allergic postnasal drip. If sinusitis is suspected, antibiotics may be needed.

2. Asthma (Cough-Variant Asthma)

What it is: Asthma can present primarily as a chronic cough without prominent wheezing, a form called cough-variant asthma, which is easily missed.

Why it happens: In asthma, airway inflammation and hypersensitivity cause the airways to react to triggers (cold air, exercise, allergens, smoke) with coughing rather than (or in addition to) wheezing and breathlessness.

Common symptoms: Dry or minimally productive cough, often worse at night or with exercise; triggered by cold air, smoke, strong scents, or allergen exposure; may not be accompanied by wheeze; spirometry may show reversible airflow obstruction.

Risk factors: Family history of asthma or allergies, eczema, environmental allergen exposure, previous respiratory infections.

When to seek evaluation: A persistent cough that worsens at night or with exercise and has no clear other cause should prompt evaluation for asthma, including spirometry. Inhaled bronchodilators and corticosteroids are the standard treatment.

3. Gastroesophageal Reflux Disease (GERD)

What it is: Acid reflux into the esophagus and occasionally into the throat and airways can trigger a chronic, dry cough even without heartburn being a prominent symptom.

Why it happens: Refluxed acid irritates the upper esophagus and triggers vagal nerve reflexes that stimulate coughing, or micro-aspiration of acid into the airway directly triggers cough receptors. Up to 40% of people with GERD-related cough do not have obvious heartburn, this is called "silent GERD."

Common symptoms: Chronic dry cough, often worse after eating or when lying down; may be associated with heartburn, sour taste, hoarseness, or throat clearing; cough that worsens with alcohol, fatty foods, or large meals.

Risk factors: Obesity, pregnancy, spicy or fatty foods, alcohol, smoking, lying down after meals.

When to seek evaluation: A trial of acid suppression (PPIs) and lifestyle modification can both diagnose and treat GERD-related cough. Formal evaluation may include pH monitoring or endoscopy if the diagnosis is uncertain.

4. ACE Inhibitor Medications

What it is: A dry, tickling, persistent cough is a well-recognized side effect of angiotensin-converting enzyme (ACE) inhibitor medications, used commonly for high blood pressure and heart failure.

Why it happens: ACE inhibitors block the breakdown of bradykinin, a peptide that accumulates in the airway and stimulates cough receptors. This effect occurs in 5-20% of people taking ACE inhibitors.

Common symptoms: Dry, persistent cough beginning weeks to months after starting an ACE inhibitor (e.g., lisinopril, enalapril, ramipril); cough resolves within 1-4 weeks of stopping the medication.

Risk factors: ACE inhibitor use; more common in women and in people of Asian descent.

When to seek evaluation: If an ACE inhibitor cough is suspected, discuss switching to an ARB (angiotensin receptor blocker) with the prescribing provider, ARBs provide similar benefits without causing cough.

5. Chronic Obstructive Pulmonary Disease (COPD)

What it is: A group of progressive lung diseases (emphysema and chronic bronchitis) in which chronic cough, often with mucus production, is a hallmark feature.

Why it happens: Smoke-damaged airways produce excess mucus and become inflamed and narrowed. The chronic cough is partly protective, an attempt to clear mucus from obstructed airways.

Common symptoms: Chronic cough with mucus (especially in the morning), worsening shortness of breath on exertion, wheezing, recurrent chest infections; history of significant smoking.

Risk factors: Cigarette smoking (primary cause), occupational exposure to dust or fumes, alpha-1 antitrypsin deficiency.

When to seek evaluation: Any current or former smoker with a persistent cough should be evaluated for COPD with spirometry. Early treatment improves quality of life and slows progression.

6. Pertussis (Whooping Cough)

What it is: A highly contagious bacterial infection caused by Bordetella pertussis, causing severe, prolonged coughing spells.

Why it happens: The bacteria produce toxins that paralyze airway cilia and cause profound airway inflammation, resulting in intense coughing fits that can last for weeks to months ("the 100-day cough").

Common symptoms: Initial cold-like symptoms followed by severe, prolonged coughing fits; the characteristic "whoop" (a gasping inhalation after a coughing fit) is more common in children; adults may have prolonged coughing without the whoop; vomiting after coughing fits.

Risk factors: Unvaccinated or under-vaccinated individuals; immunity from childhood vaccination wanes, making boosters (Tdap) important for adults.

When to seek evaluation: Pertussis requires antibiotic treatment (most effective early) and is a reportable disease. It can be severe in infants, whooping cough should be considered in anyone with a cough lasting more than 2 weeks after a cold-like onset, especially if they have not had a Tdap booster.

When to Seek Medical Care

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