When you take nitrofurantoin, an antibiotic commonly prescribed for urinary tract infections. Also known as Furadantin, it works well for simple bladder infections—but for some people, it can trigger a hidden and dangerous reaction in the lungs. This isn’t just a cough or a cold. Nitrofurantoin pulmonary toxicity is a real, documented injury to lung tissue, and it can happen even after weeks or months of use.
The most common form is acute interstitial pneumonitis, a sudden inflammation of the tiny air sacs and surrounding tissue in the lungs. Symptoms include shortness of breath, dry cough, fever, and fatigue—often mistaken for a respiratory infection. But if you’ve been on nitrofurantoin and these symptoms show up, especially if you’re over 65 or have kidney problems, it’s not a virus. It’s your lungs reacting to the drug. There’s also a slower, more dangerous version called chronic interstitial pneumonitis, a long-term lung scarring condition that can develop after months of use. Once scarring sets in, it’s often permanent, even after stopping the drug.
Who’s most at risk? Older adults, people with reduced kidney function (because nitrofurantoin builds up in the body), and those taking it for more than a month. It’s not common—maybe 1 in 1,000 users—but when it happens, it’s serious. Many doctors don’t connect lung symptoms to a urinary antibiotic, so diagnosis gets delayed. That’s why it’s critical to speak up if you feel unusual breathlessness while on this medication. A chest X-ray or CT scan can spot the changes early, and stopping the drug right away is the only way to prevent worsening damage.
You won’t find nitrofurantoin pulmonary toxicity listed as a side effect on most pharmacy labels. It’s buried in the fine print. But if you’ve been prescribed this drug for a recurring UTI, or if you’re on it long-term for prevention, you need to know this isn’t just about stomach upset or dark urine. Your lungs are in play too. The good news? Most people recover fully if caught early. The bad news? If ignored, it can lead to permanent lung damage or even require oxygen therapy.
In the posts below, you’ll find real-world cases, expert guidance on spotting early signs, and comparisons with other antibiotics that carry similar—but less known—lung risks. You’ll also see how drug monitoring, kidney function tests, and patient reporting can make all the difference. This isn’t theoretical. People are affected every day. Knowing the signs could save your lungs.
Some common medications can silently scar your lungs, causing drug-induced pulmonary fibrosis. Learn which drugs are most dangerous, how to spot early signs, and what to do before it's too late.