Chronic Cough Causes - IA-SPICE Mnemonic

By -VHTC

26 July

Coughing is one of the most common reasons people seek medical attention, but when a cough lasts longer than 8 weeks, it's classified as chronic cough—a symptom that can be frustrating for patients and challenging for clinicians.

Understanding the differential diagnosis of chronic cough is crucial, and that’s where medical mnemonics like IA-SPICE come in handy. This clever acronym summarizes key causes that should always be considered during evaluation.

In this guide, we will explore each element of IA-SPICE, backed by clinical insights, underlying pathophysiology, diagnostic approaches, and management strategies.

What is Chronic Cough?

Chronic cough is defined as a cough lasting more than:

8 weeks in adults
4 weeks in children

It’s often dry or non-productive, but in some conditions, such as cystic fibrosis or post-infectious bronchitis, it can be productive (wet).

Chronic cough is not a disease in itself—it’s a symptom of an underlying condition.

Chronic Cough Causes - IA-SPICE Mnemonic

Overview of the IA-SPICE Mnemonic

Let’s decode the mnemonic IA-SPICE, which stands for:

I – Idiopathic
A – Airway obstruction
S – Sjögren’s and other inflammatory disorders
P – Post-infectious causes
I – Immunodeficiency
C – Cystic fibrosis
E – Esoterica (e.g., Young’s syndrome)

This structured approach ensures we cover a wide spectrum of respiratory, immunological, and systemic diseases.

I – Idiopathic Chronic Cough

Sometimes, all tests come back normal, and no definitive cause is found. This is termed Idiopathic chronic cough.

Possible Mechanisms:

Hypersensitive cough reflex syndrome
Neuropathic causes (e.g., vagal sensory neuropathy)

Clinical Features:

Persistent dry cough
Triggers: talking, cold air, perfumes
No abnormal imaging or labs

Management:

Neuromodulators: Gabapentin or amitriptyline
Speech therapy
Avoidance of known triggers

A – Airway Obstruction

This refers to structural or functional narrowing of airways.

Causes:

Asthma
Chronic obstructive pulmonary disease (COPD)
Foreign body aspiration
Tumors or mediastinal masses
Tracheomalacia

Clinical Clues:

Wheezing
Dyspnea
Stridor in upper airway obstruction
Cough that worsens with exertion

Diagnosis:

Chest X-ray, spirometry, CT thorax, bronchoscopy

Treatment:

Bronchodilators
Steroids
Surgical intervention for tumors or foreign body

S – Sjögren’s Syndrome & Other Inflammatory Conditions

Chronic cough is frequently associated with autoimmune diseases, especially Sjögren’s syndrome.

Mechanisms:

Xerotrachea (dry trachea)
Associated interstitial lung disease (ILD)

Other Inflammatory Causes:

Sarcoidosis
Rheumatoid arthritis
Systemic lupus erythematosus (SLE)

Symptoms:

Dry eyes and mouth (Sjögren's)
Joint pain
Fatigue

Investigations:

ANA, anti-Ro/La, HRCT chest

P – Post-Infectious Cough

Cough may linger for weeks after infection resolution, especially in viral or bacterial respiratory illnesses.

Common Triggers:

Pertussis (whooping cough)
Pneumonia
COVID-19
RSV and influenza viruses

Mechanism:

Temporary airway hyperresponsiveness
Mucosal irritation

Timeline:

Cough persists for >3 weeks after infection
Resolves gradually over 6–8 weeks

Treatment:

Reassurance is key
Occasionally, inhaled bronchodilators or steroids help

I – Immunodeficiency

Individuals with immune system dysfunction are more prone to persistent infections, leading to chronic cough.

Types:

Primary immunodeficiencies (e.g., CVID)
Secondary causes: HIV, chemotherapy, immunosuppressive therapy

Associated Infections:

Recurrent bronchitis
Pneumocystis pneumonia (PCP)
CMV or EBV in immunocompromised hosts

Diagnostic Tests:

Immunoglobulin levels
HIV testing
CD4 count

Management:

Treat underlying immune issue
Prophylactic antibiotics in severe cases

C – Cystic Fibrosis

Cystic Fibrosis (CF) is a genetic disorder affecting chloride transport, leading to thick mucus production.

Features:

Persistent productive cough
Recurrent lung infections
Clubbing
Pancreatic insufficiency

Diagnosis:

Sweat chloride test
Genetic testing (CFTR gene)

Management:

Airway clearance therapy
Mucolytics
Antibiotics
CFTR modulators

E – Esoterica (Young’s Syndrome)

This refers to rare or unusual causes of chronic cough.

Example: Young’s Syndrome

Similar to CF: thick mucus and male infertility
Normal sweat chloride test
Cause: possibly environmental toxins or childhood infections

Other Esoteric Causes:

Primary ciliary dyskinesia
Bronchiolitis obliterans
Tracheoesophageal fistula

Diagnostic Tools:

High-resolution CT (HRCT)
Bronchoscopy
Ciliary beat frequency tests

Summary Table: IA-SPICE Mnemonic for Chronic Cough

Mnemonic	Cause	Description	Key Clues
I	Idiopathic	No identifiable cause	Hypersensitive cough reflex
A	Airway obstruction	Narrowed airway due to asthma, tumor, COPD	Wheeze, dyspnea
S	Sjögren’s & other inflammation	Autoimmune-related dryness or ILD	Dry eyes, HRCT changes
P	Post-infectious	Cough persists post pneumonia or viral illness	History of recent infection
I	Immunodeficiency	Recurrent infections	HIV, CVID, neutropenia
C	Cystic Fibrosis	Thick mucus, genetic disorder	Clubbing, positive sweat test
E	Esoterica	Rare causes like Young’s syndrome	Infertility + thick sputum

Differential Diagnosis: Expanding Beyond IA-SPICE

Although IA-SPICE is a brilliant framework, other major causes of chronic cough include:

GERD (Gastroesophageal reflux)
Postnasal drip
ACE inhibitor use
Smoking or vaping
Habit cough in children

Consider the broader mnemonic: GAPES (GERD, Asthma, Postnasal drip, Eosinophilic bronchitis, Smoking)

Diagnostic Approach

A logical step-wise evaluation includes:

1. History & Physical Exam

Duration, triggers, sputum

2. Chest X-ray

Rule out malignancy, pneumonia

3. Spirometry with bronchodilator response

4. Empirical trials

PPI for GERD, antihistamines for PND

5. Advanced imaging

HRCT, bronchoscopy if needed

FAQs

How long is a cough considered chronic?

A cough lasting more than 8 weeks in adults is chronic.

Can chronic cough be serious?

Yes. While often benign, it can also indicate lung cancer, tuberculosis, or interstitial lung disease.

What is the most common cause of chronic cough?

In non-smokers not on ACE inhibitors, the “big three” causes are:

Asthma
GERD
Postnasal drip

What if cough persists despite treatment?

This is classified as refractory chronic cough. Referral to a pulmonologist and further testing is warranted.

Chronic Cough Causes - IA-SPICE Mnemonic

What is Chronic Cough?

Overview of the IA-SPICE Mnemonic

I – Idiopathic Chronic Cough

Possible Mechanisms:

Clinical Features:

Management:

A – Airway Obstruction

Causes:

Clinical Clues:

Diagnosis:

Treatment:

S – Sjögren’s Syndrome & Other Inflammatory Conditions

Mechanisms:

Other Inflammatory Causes:

Symptoms:

Investigations:

P – Post-Infectious Cough

Common Triggers:

Mechanism:

Timeline:

Treatment:

I – Immunodeficiency

Types:

Associated Infections:

Diagnostic Tests:

Management:

C – Cystic Fibrosis

Features:

Diagnosis:

Management:

E – Esoterica (Young’s Syndrome)

Example: Young’s Syndrome

Other Esoteric Causes:

Diagnostic Tools:

Summary Table: IA-SPICE Mnemonic for Chronic Cough

Differential Diagnosis: Expanding Beyond IA-SPICE

Diagnostic Approach

FAQs

How long is a cough considered chronic?

Can chronic cough be serious?

What is the most common cause of chronic cough?

What if cough persists despite treatment?

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