Breathlessness Is Not Always Asthma: How ILD Differs From Asthma and COPD

Breathlessness and cough are common symptoms of several lung conditions, including interstitial lung disease (ILD), asthma, and chronic obstructive pulmonary disease (COPD). Because their symptoms can overlap, it may be easy to assume that persistent breathing problems are caused by asthma or COPD.

However, these conditions affect different parts of the lungs and require different approaches to diagnosis and treatment. Understanding the differences can help people recognise when persistent or worsening breathlessness needs further evaluation. For this, we spoke to Dr Shivaraj A L, Lead Consultant and HOD – Pulmonology, Aster Whitefield Hospital and Dr Sunil Kumar K, Lead Consultant - Interventional Pulmonology, Aster CMI Hospital, Bangalore, and curated this article based on their insights.

What Is Interstitial Lung Disease?

Interstitial lung disease is a group of disorders that mainly affect the lung tissue between the air sacs, known as the interstitium. In ILD, inflammation and/or scarring can damage this tissue.

According to a report published in the Journal of Clinical Medicine, as the disease progresses, the lungs may become stiff and less able to expand properly. Scarring can also interfere with the movement of oxygen from the lungs into the bloodstream.

One of the most common symptoms is gradually worsening breathlessness, particularly during physical activity. A persistent, usually dry cough is another common feature.

ILD has many possible causes. These can include autoimmune diseases, long-term exposure to certain dusts or chemicals, some medicines, and environmental factors. In some people, however, the exact cause may not be identified.

How Is Asthma Different?

Asthma primarily affects the airways, rather than causing scarring of the lung tissue.

In asthma, the airways become inflamed and overly sensitive. This can cause them to narrow temporarily, making it harder for air to move in and out of the lungs.

Typical symptoms include:

• Wheezing
• Breathlessness
• Chest tightness
• Cough

Asthma symptoms can vary significantly from one person to another and may come and go. They can be triggered by allergens, respiratory infections, exercise, smoke, air pollution, or other irritants.

An important feature of asthma is that the airway narrowing is often variable and can improve considerably with appropriate treatment. Lung function may therefore be normal between episodes in some people.

Also Read: Common Triggers of Asthma During Seasonal Change That You Need to Stay Safe From

How Is COPD Different?

COPD is another long-term respiratory condition involving airflow limitation. It commonly develops after prolonged exposure to harmful substances, particularly cigarette smoke, biomass fuel smoke and other airborne particles.

People with COPD may experience:

• Persistent cough
• Phlegm or sputum production
• Breathlessness, particularly during activity
• Reduced exercise tolerance

Unlike asthma, the airflow limitation in COPD is generally persistent and is not usually completely reversible.

COPD can include conditions such as emphysema, in which the air sacs become damaged, and chronic bronchitis, which involves long-term inflammation and mucus production in the airways.

ILD vs Asthma vs COPD: Key Differences

A cross-sectional study published in the journal 'Respiratory Research' conducted in two hospitals using electronic nose technology, established key differences between interstitial lung disease and other respiratory conditions.

The simplest way to understand the difference is to look at what part of the respiratory system is mainly affected.

This distinction is important because similar symptoms do not necessarily mean the same disease.

How Are These Conditions Diagnosed?

The diagnostic process also differs.

For ILD, doctors may use pulmonary function tests and a high-resolution CT scan of the chest to look for patterns of inflammation or scarring. Doctors may also investigate possible autoimmune, occupational, environmental, or medication-related causes.

Asthma is generally assessed using a person's symptoms and lung-function tests such as spirometry. Doctors may also assess whether breathing improves after using a bronchodilator.

COPD is primarily diagnosed through spirometry, which can demonstrate persistent airflow obstruction. A person's smoking history and exposure to other harmful particles may also provide important clues.

Also Read: Can Your Lungs Fully Recover After Years of Smoking?

Why Getting the Right Diagnosis Matters

Persistent breathlessness should not automatically be labelled as asthma or COPD. ILD can initially resemble other respiratory conditions, but it involves a different process within the lungs.

Some forms of ILD can progress and cause permanent lung fibrosis. Early identification can therefore be important for monitoring the disease, identifying a possible underlying cause and considering appropriate treatment.

If breathlessness is persistent, unexplained or gradually worsening, particularly if it is accompanied by a persistent dry cough or reduced ability to perform everyday activities, it is important to seek medical evaluation.

A pulmonologist can assess the symptoms and determine whether further lung-function testing or imaging is needed.

Final Word

Although ILD, asthma and COPD can all cause cough and breathlessness, they are not the same conditions. ILD mainly involves inflammation and scarring of lung tissue, asthma involves variable narrowing of the airways, while COPD causes persistent airflow limitation associated with long-term lung damage.

Recognising these differences can help prevent persistent breathing symptoms from being dismissed as ‘just asthma’ and ensure that people with unexplained or progressive symptoms receive the right evaluation.