Defining Acute, Subacute, and Chronic Cough: A Clinical Framework

How long has that cough been going on? It's one of the first questions primary care clinicians may ask patients presenting with persistent cough—and for good reason. The duration of cough symptoms is not just a data point; it is a critical diagnostic tool that narrows your differential and guides management decisions.

In this video interview at FMX 2025, Vukiet Tran, MD, an emergency, family medicine, and long-term care physician, breaks down the clinical framework for classifying cough by duration and explains why these distinctions matter for diagnosis and treatment. Whether you're evaluating a patient in urgent care or managing chronic symptoms in your continuity clinic, understanding these timeframes will sharpen your diagnostic approach.

In this segment, Dr Tran covers:

• The specific time cutoffs that define acute, subacute, and chronic cough
• How different pathologies present within each timeframe
• Why the differential shifts dramatically after the 8-week mark
• When to start considering serious conditions like cancer, TB, and COPD

Dr Tran is the co-founder and president of the Canadian Physicians' Pension Plan, and an assistant professor in the Department of Family and Community Medicine at the University of Toronto.

Key Takeaways

Acute Cough (<3 weeks): Think infection—typically viral, occasionally bacterial. Most resolve within 7-10 days.

Subacute Cough (3-8 weeks): The inflammatory phase. Consider upper airway cough syndrome, post-infectious cough, bronchitis, asthma exacerbations, and GERD.

Chronic Cough (> 8 weeks): Persistent symptoms signal either inadequately treated common conditions (UACS, asthma) or serious underlying pathology. This is when you must rule out malignancy, tuberculosis, COPD, heart failure, and atypical mycobacterial infections.

Clinical Pearl: If a cough persists beyond 8 weeks, it's not just about what's causing it—it's often about what we've missed or inadequately treated.