When the Cough Won't Leave: What's Really Going On

This article explains why some coughs persist long after a cold or illness has resolved, what underlying causes might be responsible, and when to seek medical evaluation.

Someone calls me about a cough that's been there for three months. "It started with a cold," they say. "Everyone else got better." There's usually a pause. "I thought it would just go away."

I hear this a lot. The cough that overstays its welcome - the one that lingers after the illness has packed up and left. Most people assume it's leftover inflammation, something that will fade on its own. Sometimes it does. But when it doesn't, when weeks turn into months, the body is trying to tell you something more specific.

The Eight-Week Threshold

We don't pick numbers arbitrarily in medicine, though sometimes it feels that way. The eight-week mark for chronic cough exists because that's when the pattern shifts. Before three weeks, you're dealing with an acute illness - flu, RSV, some viral thing making its rounds. Between three and eight weeks, you're in what we call the subacute phase. Most of the time, that's a post-viral cough, the airways still irritable from whatever infected them. But after eight weeks? That's chronic cough, and it needs a different kind of attention.

The distinction matters because the causes change. An acute cough is usually obvious - you're sick, you know why you're coughing. A chronic cough is quieter, more complicated. It can come from the lungs, but it can also come from the stomach, the sinuses, the nerves themselves. Sometimes from a medication you've been taking for years without issue.

I've seen patients cough for months, sometimes years, cycling through doctors and theories. By the time someone lands in my office - or more often, when I visit them - they're exhausted. The cough has taken over. It interrupts sleep, conversations, the simple act of sitting quietly in a room. It becomes isolating in a way that's hard to explain unless you've lived it.

The Usual Suspects

About 90% of chronic cough, when there are no red flags like weight loss or blood in the sputum, comes down to a short list: asthma, gastroesophageal reflux (GERD), postnasal drip (what we now call upper airway cough syndrome), and certain medications, particularly ACE inhibitors like lisinopril - a blood pressure medication that can trigger a persistent, dry cough in some people.

The challenge isn't knowing the list. It's figuring out which one applies, or whether it's more than one. Chronic cough rarely announces itself clearly. It doesn't always come with wheezing or heartburn or obvious sinus drainage. Sometimes it's just there - persistent, maddening, without clear explanation.

When It's the Airways: Asthma That Doesn't Wheeze

Asthma and chronic cough have a complicated relationship. Most people think of asthma as wheezing and shortness of breath, and it is - but it can also be just cough. Nothing else. No chest tightness, no audible wheeze. Just this relentless, dry cough that won't quit.

I look for patterns. Does it get worse at night? After exercise? During certain seasons? Is there a family history of allergies, eczema, or asthma? Did everyone in the house get sick, recover in a week, but this person is still coughing six weeks later? That's the kind of thing that makes me think asthmatic cough.

The diagnostic gold standard is spirometry - a breathing test where you blow into a tube as hard as you can, and we measure how much air you can push out and how fast. In asthma, there's obstruction - trouble getting air out - that improves when we give you albuterol, a bronchodilator that opens the airways. But here's the complication: spirometry can be completely normal in someone with asthma. The disease is, by definition, variable. The airways tighten and release. If we catch you on a good day, the test looks fine.

That's when we sometimes do a methacholine challenge - a test where we deliberately irritate the airways with an inhaled chemical to see if they overreact. It's provocative testing, and it can be uncomfortable, but it helps when the diagnosis is unclear.

The real proof, though, is treatment. We give a moderate to high dose of an inhaled corticosteroid - a medication that calms inflammation in the airways - for two to four weeks. If the cough improves significantly, that tells us asthma was driving it. If it doesn't, we stop the inhaler and move on. I've learned not to let therapies pile up without reassessment. If something isn't working, we need to acknowledge that and try something else.

When It's the Stomach: Reflux Without Heartburn

GERD is one of those diagnoses that gets thrown around a lot, sometimes too easily. But reflux genuinely can cause chronic cough, and it doesn't always come with the classic heartburn. The mechanism is irritation - acid or non-acid stomach contents coming up into the esophagus and larynx, triggering sensory nerves that provoke coughing. Sometimes there's microaspiration, tiny amounts of gastric material getting into the lower airways.

The tricky part is proving it. You can have reflux and a cough, but that doesn't mean the reflux is causing the cough. The gold standard used to be something called a pH probe - a thin tube placed in the esophagus to measure acid exposure over 24 hours. Now we have impedance testing, which detects both acidic and non-acidic reflux. But these tests aren't always accessible, and they're uncomfortable.

More often, we do an empiric trial - treating the reflux aggressively with a proton pump inhibitor (PPI) like omeprazole, along with lifestyle changes: elevating the head of the bed, avoiding late meals, cutting back on caffeine and alcohol. We give it time, sometimes eight to twelve weeks, because reflux-related cough takes longer to respond than you'd think.

I remember someone telling me once, "I don't have heartburn, so it can't be reflux." But reflux doesn't always burn. Sometimes it's silent. The cough is the only symptom.

When It's the Sinuses: The Drip You Don't Always Feel

Postnasal drip - or upper airway cough syndrome, the newer term - is common. The sinuses produce mucus constantly. Normally, you swallow it without noticing. But when there's inflammation - from allergies, chronic sinusitis, or just persistent irritation - the mucus thickens, accumulates, and drips down the back of the throat, triggering a cough reflex.

People often know this one. They can feel the drainage, the throat clearing, the sensation of something there. But not always. Sometimes the cough is the only sign.

Treatment depends on the cause. If it's allergies, we use antihistamines, nasal corticosteroids, sometimes saline rinses. If it's chronic sinusitis, we might need antibiotics or further investigation. The key is addressing the underlying inflammation, not just suppressing the cough.

When It's the Medication: The Cough You Didn't Expect

ACE inhibitors - medications like lisinopril, enalapril, ramipril - are excellent for blood pressure and heart failure. They're widely prescribed. And in about 10-20% of people who take them, they cause a chronic, dry cough. It's not an allergy. It's a side effect related to how the drug works, increasing levels of bradykinin - a substance that can irritate the airways.

The cough can start weeks or even months after beginning the medication. It's persistent, annoying, and doesn't respond to cough suppressants. The only treatment is stopping the drug and switching to an alternative, usually an ARB (angiotensin receptor blocker), which doesn't have the same effect.

I've seen people cough for months, trying everything, before someone thinks to check their medication list. It's such a simple fix, but it requires recognizing the connection.

The Diagnostic Dance

When someone presents with chronic cough, I work through this algorithmically, but not rigidly. I start with the history - detailed, specific. When did it start? What makes it better or worse? Any other symptoms, even subtle ones? What medications are you on?

Then I examine them. I listen to the lungs, check the throat, sometimes get imaging if the history suggests it. I do spirometry if asthma is a possibility. I ask about reflux symptoms, even if they're vague. I review the medication list.

Then comes the treatment trials. We pick the most likely cause and treat it. We give it time - not days, but weeks. If it works, great. If it doesn't, we stop and move to the next possibility. We don't pile on therapies indefinitely. That's how you end up with someone on five medications for a cough that's still there.

This process requires patience. From me, from the patient. Chronic cough doesn't usually resolve quickly. But most of the time, we get there.

When None of It Works: Refractory Cough

There's a subset of chronic cough that doesn't fit the usual categories. We've ruled out asthma, treated the reflux, addressed the sinuses, checked the medications. The cough persists. This is what we call refractory or unexplained chronic cough.

It's not that there's nothing wrong. It's that the cough has become the problem itself. The cough reflex has become hypersensitive - nerves in the airways firing in response to stimuli that shouldn't trigger coughing. It's neurogenic, a dysfunction of the sensory pathways.

This is newer territory in terms of treatment. There are emerging therapies, medications that modulate the cough reflex itself. But that's a conversation for another time, after we've exhausted the more straightforward possibilities.

What I've Learned

Chronic cough is frustrating. For the patient, obviously. But also for the doctor. It requires methodical thinking, patience, and a willingness to try, reassess, and try again. It doesn't always follow the textbook. Sometimes you treat what seems most likely and it works. Sometimes you're wrong three times before you're right.

What helps is communication - keeping the patient informed about what we're thinking, why we're trying what we're trying, what we expect to see. And honesty when something doesn't work. "This didn't help. Let's stop it and move on."

I don't always get it right the first time. I wish I did. But most of the time, eventually, we figure it out.

The cough that won't leave usually has a reason. Finding it just takes time.