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Asthma Explained: Causes, Symptoms, Triggers & Modern Treatment

Asthma is a chronic inflammatory disease of the airways affecting over 260 million people worldwide. It causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing—particularly at night or early morning. While incurable, it is highly controllable with today's therapies.

What Happens in the Airways

  1. Chronic inflammation: Immune cells (eosinophils, Th2 lymphocytes, mast cells) release mediators (histamine, leukotrienes, cytokines) causing swelling and mucus hypersecretion.
  2. Bronchial hyperresponsiveness: Airways narrow excessively to triggers that don't affect healthy people.
  3. Airway remodeling (chronic): Smooth muscle hypertrophy, fibrosis, angiogenesis—partially irreversible if untreated.

Common Triggers

CategoryExamples
AllergensDust mites, pollen, pet dander, mold, cockroach
IrritantsTobacco smoke, air pollution, strong odors, cold air, chemical fumes
InfectionsRhinovirus (common cold), influenza, RSV, COVID-19
ExerciseEspecially in cold/dry air (exercise-induced bronchoconstriction)
EmotionsStress, laughter, crying
MedicationsASA/NSAIDs (in aspirin-exacerbated respiratory disease), beta-blockers
HormonalPremenstrual, pregnancy, thyroid dysfunction

Symptom Spectrum

  • Intermittent: Symptoms ≤2 days/week, nighttime ≤2×/month
  • Mild persistent: Symptoms >2 days/week but not daily
  • Moderate persistent: Daily symptoms, nighttime ≥1×/week
  • Severe persistent: Continuous symptoms, frequent exacerbations

Symptoms vary: some cough only; others have classic wheeze. "Silent chest" in severe attacks = medical emergency.

Diagnosis

  • Spirometry: FEV₁/FVC < 0.7 (or < LLN) with ≥12% and ≥200 mL reversibility post-bronchodilator
  • Peak flow variability >20%
  • Bronchoprovocation (methacholine, mannitol, exercise) if spirometry normal
  • FeNO (fractional exhaled nitric oxide) >25 ppb supports eosinophilic inflammation

Treatment: GINA 2024 Stepwise Approach

Step 1–2: Mild Asthma

Preferred: Low-dose ICS-formoterol as-needed (reliever + controller in one).
Alternative: Daily low-dose ICS + SABA as needed.

Step 3: Moderate Asthma

Preferred: Low-dose ICS-LABA maintenance + ICS-formoterol as-needed (MART regimen).
Alternative: Medium-dose ICS-LABA maintenance + SABA reliever.

Step 4–5: Severe Asthma

Add-on options:

  • High-dose ICS-LABA
  • LAMA (tiotropium)
  • Biologics (anti-IgE, anti-IL5/5R, anti-IL4Rα, anti-TSLP) for Type 2-high phenotypes
  • Low-dose oral corticosteroids (last resort)

Essential Non-Pharmacologic Care

  • Asthma action plan: Written, personalized, reviewed annually
  • Trigger avoidance: Allergen-proof bedding, HEPA filters, no smoking
  • Vaccinations: Annual flu, COVID-19, pneumococcal
  • Comorbidity management: Allergic rhinitis, GERD, obesity, OSA
  • Exercise: Encouraged! Pre-treat with SABA if EIB; warm up gradually

Red Flags: Seek Emergency Care

  • Severe breathlessness at rest, unable to speak in phrases
  • No relief after 3–4 SABA puffs
  • Peak flow <50% personal best
  • Cyanosis, confusion, exhaustion

With proper diagnosis, a tailored action plan, and regular follow-up, most people with asthma achieve full symptom control and normal activity. Partner with your clinician—don't settle for "good enough."

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