Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease in which scar tissue progressively builds up in the lungs, making it harder to breathe. The median survival after diagnosis is 3 to 5 years, though treatments can slow the disease’s progression. “Idiopathic” means the cause is unknown, and “pulmonary fibrosis” refers to scarring of lung tissue. Most people are diagnosed between the ages of 60 and 80.
What Happens Inside the Lungs
Your lungs contain millions of tiny air sacs called alveoli, where oxygen passes into your bloodstream. In IPF, the cells lining these air sacs become repeatedly injured. The exact trigger is unknown, but the body’s repair process goes haywire. Instead of healing normally, the damaged tissue sends out chemical signals that recruit specialized cells called myofibroblasts, which deposit large amounts of collagen, a tough structural protein. This collagen builds up as scar tissue throughout the lung.
Over time, that scar tissue thickens and stiffens the walls of the air sacs, making it progressively harder for oxygen to cross into the blood. The scarring is irreversible. As more lung tissue is replaced by scar tissue, breathing becomes increasingly difficult, and the lungs lose their ability to expand fully.
Risk Factors and Genetics
Although IPF is labeled “idiopathic,” researchers have identified several factors that increase risk. Cigarette smoking is the most well-established environmental trigger. Exposure to wood dust, metal dust, and certain industrial particles has also been linked to the disease. The incidence in the United States runs roughly 4 to 8 cases per 100,000 people per year, depending on how strictly the diagnosis is defined, and men are affected more often than women.
Genetics play a significant role. A variant in a gene called MUC5B, which helps produce mucus in the airways, is found in about 38% of people with IPF compared to only 9% of the general population. Carrying one copy of this variant raises the odds of developing IPF roughly ninefold, and carrying two copies raises it more than twentyfold. Other genetic factors involve genes that maintain telomeres (the protective caps on chromosomes) and genes that produce surfactant, a substance that keeps the air sacs from collapsing. IPF likely results from a combination of genetic susceptibility and environmental exposures accumulated over a lifetime.
Symptoms and How It Feels
IPF typically begins with a dry, persistent cough and shortness of breath during physical activity. These symptoms develop gradually, often over months or years, which is one reason diagnosis is frequently delayed. Many people initially attribute the breathlessness to aging or being out of shape. As the disease progresses, even routine tasks like walking across a room or getting dressed can leave you winded.
A hallmark physical finding is “Velcro crackles,” a sound your doctor hears through a stethoscope that resembles the tearing of Velcro. About half of people with IPF also develop clubbing, a widening and rounding of the fingertips caused by chronically low oxygen levels.
How IPF Is Diagnosed
Diagnosis relies heavily on a type of CT scan called high-resolution computed tomography (HRCT). Doctors look for a specific scarring pattern known as usual interstitial pneumonia, or UIP. The defining feature is honeycombing, clusters of small, thick-walled cysts that appear in the lower and outer portions of both lungs. When honeycombing is present in this characteristic location, radiologists can identify IPF with greater than 90% confidence without needing a lung biopsy.
Another important finding on the scan is traction bronchiectasis, where scarring pulls open and distorts the airways. Progression of traction bronchiectasis over time is a strong independent predictor of mortality. Lung function testing also plays a role: a test measuring how well oxygen transfers from the lungs into the blood (called DLCO) is typically reduced. A DLCO at or above 80% of the predicted value is considered normal, but a drop of 15% or more signals worsening lung damage. Values at or below 40% of predicted indicate severe impairment.
Because other conditions can cause lung scarring, including autoimmune diseases, drug reactions, and environmental exposures, doctors must rule out all known causes before settling on an IPF diagnosis.
Antifibrotic Medications
Two medications are currently approved specifically for IPF. Both work by slowing the rate at which the lungs lose function, though neither reverses existing scarring. In clinical practice, the average annual decline in lung capacity is roughly 1.7% to 2.4% with treatment. Without treatment, that decline is substantially steeper.
The two drugs take different molecular approaches to slowing fibrosis, but head-to-head comparisons have found no significant difference in how well they preserve lung function. Side effects differ between them. One commonly causes diarrhea, while the other is more likely to cause nausea, skin sensitivity to sunlight, and liver enzyme elevations. Your doctor will choose based on your side-effect profile and tolerability. Many people stay on one of these medications indefinitely, switching to the other if side effects become unmanageable.
Pulmonary Rehabilitation and Oxygen
Pulmonary rehabilitation, a structured program of exercise training, breathing techniques, and education, produces meaningful improvements for people with IPF. Studies show that participants walk farther on standard fitness tests, experience less shortness of breath, report better quality of life, and show improvements in anxiety and depression scores. People whose oxygen levels drop during exercise see even greater gains from rehabilitation, likely because the supervised environment allows them to push their limits safely with supplemental oxygen available.
Supplemental oxygen becomes necessary when blood oxygen levels fall too low, particularly during activity or sleep. It won’t slow the scarring, but it reduces breathlessness, helps you stay more active, and protects your heart from the strain of working against low oxygen levels. Many people start with portable oxygen during exercise and eventually need it throughout the day as the disease progresses.
Lung Transplantation
For people with advanced IPF who are otherwise healthy enough, lung transplantation remains the only option that can significantly extend life. IPF is now the leading reason for lung transplants worldwide. Five-year survival after transplant has improved over the past two decades, reaching about 55% in the most recent era studied. That improvement has come despite transplant recipients being sicker at the time of surgery than in previous years, reflecting advances in surgical techniques and post-transplant care.
Not everyone is a candidate. Age, overall health, body weight, and the presence of other medical conditions all factor into eligibility. The evaluation process itself takes weeks to months, and wait times for a suitable donor lung vary widely by region. People who are referred early in their disease course have more options than those referred after significant decline.
Living With IPF
IPF follows a variable course. Some people remain relatively stable for years, while others decline rapidly. Acute exacerbations, sudden worsening episodes with no clear trigger, can happen at any stage and are a leading cause of death. Avoiding respiratory infections through vaccination and hand hygiene is important, as infections can trigger these flares.
Staying physically active within your limits, maintaining a healthy weight, and participating in pulmonary rehabilitation all help preserve function longer. Many people benefit from joining a support group, since the psychological burden of a progressive lung disease is substantial. Anxiety and depression are common and treatable, and addressing them directly improves both quality of life and the ability to stay engaged with treatment.