Chronic Cough Workup: How to Diagnose GERD, Asthma, and Postnasal Drip

Why Your Cough Won’t Go Away

If you’ve been coughing for more than eight weeks, you’re not alone. About 1 in 10 adults deal with a cough that just won’t quit. And most of the time, it’s not because of a cold, the flu, or even allergies. It’s usually one of three things: GERD, asthma, or postnasal drip-now more accurately called upper airway cough syndrome. These three causes make up 80 to 95% of chronic cough cases in people who don’t smoke or take ACE inhibitor blood pressure meds. The good news? Once you know what’s triggering it, relief is often just weeks away.

What Counts as a Chronic Cough?

A cough that lasts longer than eight weeks is officially chronic. That’s not just a random number-it’s based on decades of clinical research and guidelines from the American College of Chest Physicians. If your cough started suddenly after a cold, it’s probably still part of the healing process. But if it’s been hanging on for months, especially if it’s worse at night, after meals, or when you lie down, it’s time to look beyond the common cold.

Before you jump to treatments, you need to rule out the red flags: coughing up blood, unexplained weight loss, fever, or abnormal breathing sounds. These could point to something serious like lung cancer, tuberculosis, or heart failure. A simple chest X-ray is the first step. If it’s normal-which it usually is-you’re likely dealing with one of the big three.

Postnasal Drip (Upper Airway Cough Syndrome)

For decades, doctors called this condition “postnasal drip.” But that term is misleading. It’s not just mucus dripping down your throat-it’s your airways becoming overly sensitive because of inflammation in your nose and sinuses. That’s why the term upper airway cough syndrome (UACS) is now preferred.

UACS is the most common cause of chronic cough, responsible for 38 to 62% of cases. You might notice a constant need to clear your throat, a tickle in the back of your throat, or a feeling of something stuck there. It often gets worse in the morning or after lying down. Allergies, colds, or sinus infections can trigger it, and sometimes it’s just chronic inflammation without a clear cause.

The diagnosis? It’s simple: try treatment before testing. A two- to three-week course of a first-generation antihistamine like diphenhydramine (Benadryl) plus a decongestant like pseudoephedrine usually does the trick. If your cough improves by 70 to 90%, you’ve got UACS. No need for CT scans or nasal endoscopies-unless the treatment fails.

Asthma (Especially Cough Variant Asthma)

Most people think of asthma as wheezing and shortness of breath. But about a quarter of adult asthma cases show up as nothing more than a dry, hacking cough. This is called cough variant asthma. It’s sneaky because you might not wheeze at all, and your lung function looks normal on a basic breathing test.

Here’s how to spot it: Does your cough get worse at night? After exercise? Around cold air or strong smells? Do you have a history of allergies, eczema, or asthma in your family? If yes, it’s worth checking.

The gold standard test is a methacholine challenge. If your lungs react to a small dose of methacholine (a substance that causes airway narrowing in sensitive people), it confirms asthma-even if your spirometry looks fine. A 12% or greater improvement in your FEV1 after using an inhaler like albuterol also supports the diagnosis.

Treatment is straightforward: inhaled corticosteroids (like fluticasone) or a combination inhaler (like Advair). Most people see improvement in two to four weeks. If you don’t, it’s not asthma-or you’re not taking it right. Many patients stop their inhalers too soon because they feel better after a few days. That’s a mistake. You need to stick with it for at least four weeks to know if it’s working.

GERD and Silent Reflux

GERD-gastroesophageal reflux disease-is responsible for 21 to 41% of chronic coughs. But here’s the twist: most people with GERD-related cough don’t have heartburn. Up to 70% of them have what’s called “silent reflux.” They might feel a lump in their throat, a sour taste in the morning, or hoarseness-but no burning chest pain.

That’s why treating it with a proton pump inhibitor (PPI) like omeprazole or esomeprazole has become controversial. A 2024 update from the American College of Gastroenterology now says: don’t just start PPIs blindly. The placebo effect is strong-35 to 40% of people improve even on sugar pills. And only about half of those with true GERD-related cough respond to PPIs.

So what’s the better approach? First, try lifestyle changes: avoid eating within three hours of bedtime, cut out caffeine, alcohol, chocolate, and spicy foods, and raise the head of your bed by 6 inches. If that doesn’t help, then try a high-dose PPI (like 40 mg of esomeprazole twice a day) for four to eight weeks. If your cough improves, GERD was likely the cause.

For confirmation, some doctors use pH impedance monitoring-a tube that measures acid and non-acid reflux in your esophagus over 24 hours. But it’s expensive, not always covered by insurance, and not always needed if you respond to treatment.

The Diagnostic Algorithm: What to Do First

Doctors don’t test for everything at once. That’s expensive, unnecessary, and frustrating. Instead, they follow a step-by-step path:

1. Stop any ACE inhibitor medications (like lisinopril or enalapril)-they cause cough in up to 35% of users.
2. Get a chest X-ray to rule out tumors, infections, or structural problems.
3. Do spirometry to check lung function. Normal results don’t rule out asthma.
4. Ask about smoking, environmental exposures, and medication history.
5. Start a therapeutic trial: UACS first (antihistamine + decongestant), then asthma (inhaled steroid), then GERD (PPI).

Why this order? Because UACS and asthma respond faster and more reliably. If you try GERD first and it doesn’t work, you’ve wasted eight weeks. And if you try all three at once, you won’t know which treatment helped.

What If Nothing Works?

Even after ruling out the big three, 10 to 30% of people still have a chronic cough. That’s when you look at rarer causes:

• Chronic refractory cough (CRC): A condition where the nerves in your airways become hypersensitive. It’s not caused by GERD, asthma, or UACS-it’s just the cough reflex going haywire.
• Pertussis (whooping cough): Rare in adults, but it can linger for months. A nasal swab test can confirm it.
• Chronic aspiration: When food or liquid goes into the lungs instead of the stomach-common in older adults or those with swallowing problems.
• Medication side effects: Besides ACE inhibitors, some diabetes drugs and heart meds can cause cough.

New treatments are emerging. In late 2022, the FDA approved gefapixant, a drug that blocks the P2X3 receptor involved in cough reflex sensitivity. In trials, it reduced cough frequency by 18 to 22%. Another drug, camlipixant, showed even better results in 2024 trials. These aren’t first-line treatments yet-but they’re changing the game for people who’ve tried everything.

What You Can Do Today

You don’t need to wait for a specialist. Start here:

• Stop any ACE inhibitor meds-ask your doctor if you’re on one.
• Keep a cough diary: note when it happens, what triggers it, and how bad it is.
• Try a simple antihistamine like loratadine (Claritin) for a week-no decongestant needed yet.
• Elevate your head while sleeping and avoid late-night meals.
• Don’t smoke, and avoid secondhand smoke or strong perfumes.

If you don’t improve in two weeks, see your doctor. Bring your diary. Ask about spirometry and whether a trial of an inhaler or PPI makes sense. Most people get better with the right approach-no fancy scans or expensive tests needed.

Why This Matters

Chronic cough isn’t just annoying-it’s exhausting. It disrupts sleep, makes you anxious, and can even lead to urinary incontinence or broken ribs. And the cost? In the U.S. alone, it drives over $650 million in annual healthcare spending. Most of that goes to unnecessary tests, antibiotics, and imaging that don’t help.

The real win? Getting the diagnosis right the first time. You don’t need to suffer for years. With a clear, step-by-step plan focused on the big three causes, relief is possible. And with new drugs on the horizon, even the toughest cases have hope.