What Are Crackles?
Crackles are short, interrupted popping or clicking sounds you hear when listening to the lungs with a stethoscope, caused by small airways that have abnormally closed suddenly popping open during breathing, or by air bubbling through fluid in the lungs. 1
How Crackles Sound
- Fine crackles sound like rubbing hair between your fingers near your ear, or like the sound of Velcro being pulled apart—they're soft, high-pitched, and brief 2, 3
- Coarse crackles sound like bubbling or gurgling, are louder and lower-pitched, and suggest fluid or mucus in larger airways 3
- The sounds typically occur during breathing in (inspiration), though timing varies by what's causing them 1
What Crackles Mean
Fine Crackles Usually Indicate:
- Scarring of the lungs (pulmonary fibrosis): Fine crackles with a "Velcro" quality are heard in over 80% of patients with idiopathic pulmonary fibrosis, typically starting at the bottom of the lungs and heard at the end of breathing in 2, 3
- Heart failure with fluid backup: Fine crackles at the lung bases that may spread upward as fluid accumulates 3
- Pneumonia: Crackles increase the likelihood of pneumonia when combined with other symptoms like fever and cough 4, 3
- Asbestos-related lung disease: Bilateral late inspiratory crackles at the back lower lung areas are a recognized sign 4, 3
Coarse Crackles Usually Indicate:
- Bronchiectasis (damaged, widened airways): Coarse crackles suggest mucus and secretions in larger airways 3
- Severe pulmonary edema: When significant fluid has accumulated 3
Important Context
- Not always abnormal: Healthy people without lung disease can sometimes have crackles over the front lower chest when breathing in from a very empty lung position, but these disappear with normal breathing 5
- Very common finding: Crackles are one of the most frequent abnormal lung sounds doctors listen for during physical examination 4
- Requires further testing: The presence of fine crackles, especially the "Velcro" type at the lung bases, should prompt imaging with a chest X-ray or CT scan to look for underlying lung disease 2