Is Interstitial Lung Disease the Same as COPD? Explained

No, interstitial lung disease (ILD) and chronic obstructive pulmonary disease (COPD) are different disease categories with different primary mechanisms and medical treatments. While they can cause similar symptoms—such as shortness of breath and a persistent cough—and can sometimes overlap, they typically affect different structures in your lungs. COPD is broadly an obstructive lung disease that primarily affects the airways (the breathing tubes), making it difficult to push air out ^[1]. In contrast, ILD is a group of diseases that primarily affects the tissue around the air sacs (the interstitium), often making the lungs stiff and hard to expand when you try to breathe in ^[2][3].

Because their primary mechanisms differ, it is important to know which condition you have so that you receive the most effective care.

How They Affect the Lungs

To understand the difference, it helps to picture the anatomy of your lungs. When you breathe, air travels through a network of tubes (airways) until it reaches tiny air sacs where oxygen enters your blood.

• COPD (Focus on Airways and Air Sacs): In COPD, which includes chronic bronchitis and emphysema, the airways become inflamed or damaged, and the delicate walls of the air sacs can be destroyed. This creates persistent airflow limitation—meaning the air gets trapped, and it takes extra effort to exhale completely ^[4].
• ILD (Focus on the Interstitium): ILD is a broad term for more than 100 conditions that can cause inflammation or scarring (fibrosis) in the supportive tissue surrounding the air sacs ^[5]. In fibrotic ILDs, this scarring makes the lung tissue stiff and inflexible, much like a dried sponge, restricting how much air the lungs can hold ^[2]. This often results in a restrictive pattern on pulmonary function tests (PFTs).

Both conditions can cause progressive shortness of breath, fatigue, and lower oxygen levels in the blood (hypoxemia) ^[6][7]. However, disease behavior varies widely depending on the specific ILD subtype and the individual.

Safety Note: Routine chronic symptoms should be discussed with your care team during normal appointments. However, seek urgent medical care if you experience sudden or severe breathlessness, chest pain, confusion, fainting, or blue lips.

Differences in Treatment

Because the root causes of the breathing difficulties are different, their primary medical therapies are not the same. However, they do share some supportive care, such as smoking cessation, vaccinations, pulmonary rehabilitation, and oxygen therapy if indicated by oxygen testing.

• Treating COPD: The cornerstone of COPD treatment relies on bronchodilators. These are inhaled medications that relax the muscles around the airways to open up the breathing tubes, making it easier to exhale ^[8][9].
• Treating ILD: ILD treatment is customized to the specific underlying cause and subtype ^[10]. If the disease involves progressive scarring, doctors may prescribe antifibrotics—medications taken as pills that help slow down the rate of lung scarring, though they generally do not reverse existing damage ^[11][12]. If the ILD is driven by an autoimmune condition, treatment may involve immunosuppressants to calm the immune system and halt inflammation ^[13][14].

Important Note: Immunosuppressants are not used for all ILDs and can actually be harmful in some types, like idiopathic pulmonary fibrosis. Some patients may need immunomodulatory therapy, antifibrotic therapy, both, or neither. Similarly, inhalers are not the primary treatment for fibrotic lung disease, but if you have ILD, do not stop a prescribed inhaler without asking your clinician. You may have coexisting airway issues that the inhaler is actively treating.

Can You Have Both?

Yes, it is possible for a person to have both COPD and ILD at the same time. There is also a specific clinical-radiologic syndrome called Combined Pulmonary Fibrosis and Emphysema (CPFE), which involves both emphysema and pulmonary fibrosis, usually confirmed on a CT scan ^[15].

Having both obstruction and restriction can make standard lung function tests tricky to interpret. The airway obstruction from emphysema and the lung stiffness from fibrosis can sometimes balance each other out, making your total lung volume look relatively normal, even while the lungs’ ability to transfer oxygen (measured by the DLCO test) is severely impaired ^[15]. If you have overlapping conditions, you will need a specialized care plan from a pulmonologist to manage both effectively.