Bronchitis and Asthma — Clinical Documentation Guide (2026)

🔍 Definition

Bronchitis is inflammation of the bronchial mucosa resulting in cough, mucus hypersecretion, and variable airflow obstruction. It is classified by duration and etiology:

• Acute bronchitis (J20.x): An acute lower respiratory tract infection, typically viral (90%+ of cases), lasting 1–3 weeks, characterized by cough, sputum production, and occasionally low-grade fever. Coding specificity requires identifying the causative organism when documented (CMS/CDC ICD-10-CM).
• Acute bronchiolitis (J21.x): Inflammation of the smaller bronchioles, predominantly affecting infants and children under 2 years; most commonly caused by RSV (J21.0). The clinical presentation includes wheezing, tachypnea, and hypoxia.
• Chronic bronchitis (J41.x, J42): Defined clinically as productive cough for at least 3 months per year for 2 consecutive years, as established by the WHO criteria. Simple chronic bronchitis (J41.0) produces mucoid sputum; mucopurulent chronic bronchitis (J41.1) produces purulent sputum without airflow obstruction. When neither acute nor chronic is specified and no COPD criteria are met, assign J40.
• COPD overlap (J44.x): Chronic bronchitis with airflow obstruction (FEV1/FVC <0.70) meets COPD criteria and should be coded to J44.x — see separate COPD CDG for full detail.

Asthma is a heterogeneous chronic inflammatory airway disease characterized by variable, reversible airflow obstruction, airway hyperresponsiveness, and bronchial inflammation. Per the GINA 2025 Strategy Report, asthma is defined by a history of respiratory symptoms (wheeze, shortness of breath, chest tightness, cough) that vary over time and in intensity, together with variable expiratory airflow limitation.

The FY2026 ICD-10-CM classification of asthma under J45.xx captures severity (mild intermittent, mild persistent, moderate persistent, severe persistent) and clinical status (uncomplicated, with acute exacerbation, with status asthmaticus). Eosinophilic asthma is classified separately under J82.83 (new code effective FY2025, carried forward to FY2026).

🗂️ Alternative Terminology

🩺 Signs & Symptoms

Bronchitis

• Acute bronchitis: Cough (dominant symptom), may be productive with white, yellow, or green sputum; low-grade fever; malaise; chest tightness; dyspnea on exertion; wheeze in some patients. Duration typically 7–21 days. Fever >38.5°C or purulent sputum with systemic signs may suggest bacterial superinfection or pneumonia.
• Acute bronchiolitis (pediatric): Tachypnea, intercostal/subcostal retractions, nasal flaring, expiratory wheeze, crackles, hypoxia (SpO₂ <95% in moderate-severe), feeding difficulties. Onset typically follows 2–3 days of upper respiratory symptoms.
• Chronic bronchitis: Productive cough ≥3 months/year × 2 consecutive years, increased sputum volume, recurrent respiratory infections, exertional dyspnea if airflow obstruction develops. Morning “smoker’s cough” is characteristic.

Asthma

• Classic triad: Episodic wheeze, cough (worse at night/early morning), and dyspnea or chest tightness. Symptoms are variable and often triggered by allergens, viral infections, exercise, cold air, smoke, or irritants.
• Acute exacerbation: Progressive worsening of wheeze, dyspnea, chest tightness, and cough. Accessory muscle use, pulsus paradoxus, reduced air entry, O₂ saturation <92% indicate severity.
• Status asthmaticus: Severe, prolonged asthma attack unresponsive to initial bronchodilator therapy; may progress to respiratory failure. ICU-level monitoring required. Risk factors include prior intubation, ≥2 hospitalizations/year, food allergy, and psychosocial factors (GINA 2025).
• Cough-variant asthma: Chronic cough as predominant or sole symptom; absence of typical wheeze. Diagnosis requires bronchoprovocation testing (94070) or therapeutic response to ICS.
• Exercise-induced bronchoconstriction: Cough, wheeze, dyspnea triggered by sustained aerobic exercise, typically 5–10 minutes post-exercise. May be the only asthma manifestation in athletes.

🧭 Differential Diagnosis

📋 Clinical Indicators for Coders/CDI

🦴 Anatomy & Pathophysiology

Bronchitis Pathophysiology

The bronchial tree consists of the trachea bifurcating into right and left main bronchi, which subdivide into lobar, segmental, and subsegmental bronchi, terminating in bronchioles. In acute bronchitis, viral or bacterial invasion triggers mucosal inflammation with goblet cell hyperplasia and increased mucus secretion. Ciliary dysfunction impairs mucociliary clearance, promoting cough. Submucosal edema contributes to mild airflow limitation. Most cases are caused by respiratory viruses (rhinovirus, coronavirus, influenza, parainfluenza, RSV, adenovirus) with secondary bacterial superinfection uncommon (AAPC Knowledge Center).

Acute bronchiolitis affects the terminal and respiratory bronchioles (<2 mm diameter), predominantly in infants. RSV (and human metapneumovirus) cause necrosis of the bronchiolar epithelium, luminal obstruction with mucus and cellular debris, peribronchiolar infiltration, and air trapping. The small airway diameter makes infants uniquely susceptible to hemodynamically significant obstruction.

In chronic bronchitis, prolonged noxious stimuli (primarily tobacco smoke) cause squamous metaplasia of the respiratory epithelium, goblet cell hyperplasia, hypertrophy of submucosal mucous glands (Reid index >0.4), and chronic inflammation. Unlike COPD, spirometry may remain normal in pure chronic bronchitis without emphysema.

Asthma Pathophysiology

Asthma is fundamentally a chronic inflammatory airway disease. The dominant inflammatory phenotype in allergic (atopic) asthma is Type 2 (T2)-high, driven by Th2 lymphocytes, ILC2 cells, and key cytokines IL-4, IL-5, IL-13, and TSLP. This drives IgE production, mast cell activation, eosinophil recruitment, and airway remodeling. Key pathological features include:

• Bronchoconstriction: Smooth muscle contraction in response to allergens, irritants, cold air, exercise; partially reversed by bronchodilators
• Airway edema and mucus hypersecretion: Contributes to airflow obstruction and mucus plugging
• Airway hyperresponsiveness (AHR): Exaggerated bronchoconstriction response to methacholine, histamine, exercise, or cold air; measured by bronchoprovocation testing (CPT 94070)
• Structural remodeling: Subepithelial fibrosis, smooth muscle hypertrophy/hyperplasia, increased mucous glands — occurs with chronic untreated disease and is only partially reversible
• Eosinophilic airway inflammation: In eosinophilic asthma (J82.83), blood and tissue eosinophilia (≥300 cells/µL) drives inflammatory damage; targeted by anti-IL5/IL5R biologics (AAAAI Biologics for Asthma)

Non-T2 (T2-low) asthma phenotypes include neutrophilic asthma (associated with obesity, smoking, occupational exposure) and paucigranulocytic asthma, which are less responsive to ICS and have limited biologic options. Tezepelumab (anti-TSLP) targets a broad upstream signal and has efficacy across T2-high and T2-low phenotypes.

💊 Medication Impact / Treatment

Acute Bronchitis

Treatment is primarily supportive. Antibiotics are generally NOT indicated for acute bronchitis (viral etiology in >90% of cases) per CDC antimicrobial stewardship guidance. Symptomatic management includes:

• Antitussives (dextromethorphan) or expectorants (guaifenesin) for symptom relief
• Short-acting bronchodilator (albuterol) via nebulizer (CPT 94640) if wheeze or bronchospasm present
• Inhaled corticosteroid (ICS) — short course may reduce cough duration in selected patients
• Antivirals (oseltamivir) for influenza-confirmed cases within 48 hours of onset

Acute Bronchiolitis (Pediatric)

Supportive care is the mainstay per AAP Clinical Practice Guideline: supplemental O₂ (target SpO₂ ≥90%), hydration, nasal suctioning. Bronchodilators and systemic corticosteroids are NOT routinely recommended. High-flow nasal cannula (HFNC) may be used for moderate-severe cases. Palivizumab prophylaxis for high-risk infants (premature, congenital heart disease) during RSV season.

Chronic Bronchitis

Smoking cessation (most critical intervention; use F17.2xx codes for current tobacco use), mucolytics (N-acetylcysteine), pulmonary rehabilitation, and influenza/pneumococcal vaccination. If spirometry confirms COPD, refer to COPD CDG for full treatment algorithm.

Asthma — GINA 2025 Stepwise Therapy

Per GINA 2025, all adults and adolescents should receive ICS-containing therapy. SABA-only treatment is no longer recommended at any step.

Biologic Therapy for Severe Asthma (Step 5)

Per CHEST 2026 Biologic Guidelines and ACCP 2026, biologic selection is based on phenotype:

• Allergic (T2-high, high IgE): Omalizumab (anti-IgE, Xolair) — approved ≥6 years; preferred or dupilumab for moderate-severe allergic asthma with ≥1 OCS exacerbation/year
• Eosinophilic (eos ≥300 cells/µL): Mepolizumab (Nucala, anti-IL5), benralizumab (Fasenra, anti-IL5Rα), reslizumab (Cinqair IV, anti-IL5), or dupilumab (anti-IL4Rα/IL-13)
• Mixed/Broad T2: Dupilumab (atopic dermatitis or EoE comorbidity preferred) or tezepelumab (Tezspire, anti-TSLP — efficacy across all phenotypes including T2-low)
• Aspirin-exacerbated respiratory disease (AERD): Dupilumab preferred; code J45.990 + external cause code for aspirin sensitivity

Preview ends here. The full guide continues with FY2026 ICD-10-CM code sets, CPT surgical coding, MS-DRG mapping, reimbursement guidance, CDI query templates, and an audit checklist — all available to CCO Members.

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📘 ICD-10-CM Guidelines (FY2026)

The following guidelines govern FY2026 coding for bronchitis and asthma per the CMS FY2026 ICD-10-CM Official Guidelines for Coding and Reporting:

Bronchitis Guidelines

• Acute bronchitis (J20.x): Assign a code from J20 when the provider documents “acute bronchitis.” Code to the highest level of specificity — use J20.0–J20.8 when an organism is identified or attributed; use J20.9 only when no organism is documented. Per FY2026 tabular revisions, the Excludes1 note under J20 has been changed to Excludes2 for J41.-, J42, and J42 — meaning both acute and chronic bronchitis may be coded if both exist.
• Bronchitis NOS (J40): Use only when documentation does not specify acute or chronic. Do not use J40 if the provider clearly states “acute bronchitis” or “chronic bronchitis.” J40 includes bronchitis with tracheitis when not specified as acute or chronic.
• Chronic bronchitis (J41.x, J42): J41.0 (simple) requires documentation of mucoid/clear sputum; J41.1 (mucopurulent) requires documentation of purulent sputum. J42 (chronic bronchitis unspec.) applies when neither simple nor mucopurulent is specified. Do not assign J41.x or J42 when airflow obstruction is present — assign J44.x (COPD).
• J41 vs. J44 distinction: This is a critical distinction. ICD-10-CM guidelines specify that when “chronic bronchitis with airway obstruction” or “COPD” is documented, J44.x takes precedence over J41.x. Spirometry showing FEV1/FVC <0.70 post-bronchodilator supports COPD classification.
• Acute bronchiolitis (J21.x): Used for inflammation of the bronchioles, predominantly in infants/young children. J21.0 is RSV-specific and the most common pediatric respiratory hospitalization. Bronchiolitis in adults is rare — verify clinical documentation before using J21.x for adults.
• Influenza with bronchitis: Per ICD-10-CM Section I.C.10, if bronchitis is documented as due to influenza, assign influenza codes (J09-J11) first with bronchitis as manifestation — do not assign J20.x separately as it is included in the influenza code.

Asthma Guidelines

• Severity assignment (J45.x): The fourth character identifies the severity classification (2=mild intermittent, 3=mild persistent, 4=moderate persistent, 5=severe persistent, 9=other/unspecified). The fifth character identifies clinical status: 0=uncomplicated, 1=with acute exacerbation, 2=with status asthmaticus.
• “With acute exacerbation” vs. “uncomplicated”: Assign the “acute exacerbation” code (.x1) when the provider documents worsening of symptoms, exacerbation, or flare-up requiring additional or emergency treatment. Do not presume exacerbation from symptoms alone — provider documentation is required.
• Status asthmaticus (.x2): Assign when the provider explicitly documents “status asthmaticus” or equivalent terminology indicating a severe, prolonged attack unresponsive to initial therapy. This represents the most severe form and should not be assigned based on coder inference alone. Status asthmaticus excludes acute exacerbation — do not assign both .x1 and .x2.
• Eosinophilic asthma (J82.83): This code is in category J82 (Pulmonary eosinophilia), not J45 (Asthma). When provider documents “eosinophilic asthma,” assign J82.83 as the principal diagnosis or as an additional code along with the asthma severity code (J45.xx). Code also the eosinophil count if documented (R89.98).
• Asthma-COPD overlap (ACO): When provider documents both asthma and COPD, assign both J45.xx and J44.xx per ICD-10-CM guidelines. Do not code only one — both are valid and represent distinct disease processes.
• Cough-variant asthma (J45.991): Assign when provider explicitly documents cough-variant asthma or “cough asthma.” This is a distinct phenotype, not a general asthma code for cough as a symptom.
• Exercise-induced asthma (J45.990): Note the Excludes1 note — exercise-induced bronchospasm is excluded from J45.990 in some tabular notes. Verify current FY2026 tabular for aspirin-induced asthma exclusions.
• Occupational asthma (J68.11): Assign for work-related asthma. An external cause code should accompany this code to identify the specific occupational exposure. This code is in the “Respiratory conditions due to inhalation of chemicals, gases, fumes and vapors” section.
• Additional codes: Per “Code also” instructions throughout J45 and J82.83: smoker status (F17.2xx), second-hand tobacco smoke (Z77.22), allergic rhinitis (J30.x), GERD (K21.x), OSA (G47.33), eosinophil count (R89.98 if blood eosinophilia documented).

🔢 ICD-10-CM Code Set (FY2026)

Bronchitis Codes

Asthma Codes

Additional/Associated Codes

🔎 Indexing

Key ICD-10-CM Alphabetic Index pathways for bronchitis and asthma (FY2026 ICD-10-CM Tabular):

🏥 CPT (2026)

🧾 HCPCS (2026)

📚 AHA Coding Clinic (recent guidance)

💰 HCC / Risk Adjustment (v28)

The CMS-HCC Model V28 is fully operative as of payment year 2026 (100% v28, replacing the phased transition). Key changes affecting respiratory coding include significant restructuring of the COPD and asthma HCC hierarchy.

✍️ CDI Query Templates

🧑‍⚕️ Treatments (Clinical)

Bronchitis — Clinical Treatment Summary

• Acute bronchitis: Supportive care (rest, hydration, symptom management). Antibiotics NOT routinely recommended per CDC antibiotic stewardship. Short-acting bronchodilator (albuterol MDI or nebulizer) if bronchospasm/wheeze. Over-the-counter antitussives and expectorants. COVID-19 should be ruled out in appropriate clinical context (testing before coding as acute bronchitis).
• Acute bronchiolitis (pediatric): Supportive: supplemental O₂, nasopharyngeal suctioning, IV/NG hydration if poor feeding. High-flow nasal cannula (HFNC) for moderate-severe. Heliox in select severe cases. Avoid routine epinephrine, bronchodilators, systemic steroids. Discharge when SpO₂ stable ≥90% on room air and adequate oral intake.
• Chronic bronchitis: Smoking cessation (varenicline, NRT, bupropion); mucolytics (N-acetylcysteine, erdosteine); annual influenza vaccine; pneumococcal vaccine; pulmonary rehabilitation if exertional limitation; amoxicillin-clavulanate or azithromycin for acute bacterial exacerbation.

Asthma — Clinical Treatment Summary

Based on GINA 2025 and NAEPP guidelines:

• All patients: ICS-containing treatment (no patient should receive SABA alone). Inhaler technique education (CPT 94664). Written asthma action plan. Annual influenza vaccination.
• Step 1–2 (mild): As-needed low-dose ICS-formoterol (MART regimen) preferred, OR daily low-dose ICS + as-needed SABA. Leukotriene receptor antagonist (LTRA, montelukast) as alternative — note FDA black box warning for neuropsychiatric events.
• Step 3–4 (moderate): Daily ICS-formoterol MART (single maintenance and reliever therapy) preferred. Alternative: daily medium-dose ICS-LABA + PRN SABA. Add-on LAMA (tiotropium) for Step 4 if SMART not achieving control.
• Step 5 (severe): High-dose ICS-LABA ± LAMA. Phenotype assessment essential. Add-on biologic therapy based on T2 biomarkers (IgE, eosinophil count, FeNO). Short-term oral corticosteroids (OCS) for severe exacerbations — avoid chronic OCS if possible.
• Status asthmaticus: Intensive bronchodilation (continuous albuterol nebulization, IV magnesium sulfate 2 g over 20 min), systemic corticosteroids (IV methylprednisolone J2210), supplemental O₂ (SpO₂ target ≥93–95%), monitoring for respiratory failure. Intubation with mechanical ventilation in refractory cases (use permissive hypercapnia strategy to minimize air trapping).
• Allergen immunotherapy: Subcutaneous immunotherapy (SCIT, CPT 95024) as adjunct in allergic asthma at Steps 2–4 per GINA 2025 conditional recommendation for patients ≥5 years with controlled asthma at initiation.

🎓 Patient Education / Summary

Bronchitis Patient Education

• Acute bronchitis: Most cases are caused by viruses — antibiotics will not help and may cause harm. Rest and drink plenty of fluids. Over-the-counter medications can relieve symptoms. Cough may last 2–3 weeks even after you start feeling better. See a doctor if you develop high fever, difficulty breathing, coughing up blood, or symptoms lasting more than 3 weeks. Stop smoking — smoking dramatically worsens bronchitis and delays recovery.
• Chronic bronchitis: The most important treatment is quitting smoking. This is the only intervention proven to slow progression. Annual flu shots and pneumococcal vaccine reduce your risk of serious infections. Pulmonary rehabilitation programs improve exercise tolerance and quality of life. Recognize warning signs of exacerbation (increased sputum, color change, increased shortness of breath) and have an action plan.

Asthma Patient Education

• Understanding triggers: Common triggers include allergens (pollen, pet dander, dust mites, mold), respiratory infections, cold air, exercise, smoke, strong odors, and aspirin/NSAIDs in sensitive patients. Identifying and avoiding your specific triggers is a key part of asthma management.
• Controller vs. rescue medications: Controller medications (ICS, ICS-LABA) are taken every day to prevent symptoms — they don’t work immediately if you stop them. Rescue medications (albuterol, ICS-formoterol) provide rapid relief during an episode. Know which medications you have and when to use each.
• Inhaler technique: Correct inhaler technique is critical — poor technique means less medication reaches the airways. Ask your healthcare provider or pharmacist to observe and correct your technique at each visit.
• Asthma action plan: Work with your provider to create a written plan that tells you what to do when your asthma is well-controlled (green zone), getting worse (yellow zone), or in a medical emergency (red zone). Know when to use your rescue inhaler and when to call 911 or go to the ER.
• Environmental controls: Use allergen-proof mattress/pillow covers, vacuum with HEPA filter, control indoor humidity (30–50%), avoid tobacco smoke, and consider air purifiers for bedroom.
• Biologic therapy: If your provider has prescribed an injectable medication (biologic) for severe asthma, this medication targets the specific type of inflammation driving your asthma. These medications are typically given as injections in your doctor’s office or, in some cases, can be self-administered at home after training. They are not rescue medications — they must be taken on schedule to work.
• When to seek emergency care: Signs of a severe asthma attack requiring emergency care include inability to speak more than a few words, severe shortness of breath at rest, bluish lips or fingertips, use of neck muscles to breathe, no improvement after 2–4 puffs of rescue inhaler, or SpO₂ <90%.

About this Guide

This Clinical Documentation Guide is published by CCO Academy and is intended for credentialed coding, CDI, and clinical documentation professionals. Content is updated for FY2026 ICD-10-CM (effective October 1, 2025). All code assignments should be verified against the official ICD-10-CM Tabular List, AHA Coding Clinic, and applicable payer-specific policies. This guide does not constitute legal, medical, or compliance advice.

Last reviewed: April 2026 · Next scheduled review: October 2026 (FY2027 update)