A dry cough, one that doesn’t bring up mucus or phlegm, is most often caused by irritation or inflammation in your airways rather than an active infection. In nonsmokers, more than 90% of lingering dry coughs trace back to just a handful of causes: postnasal drip, asthma, acid reflux, chronic bronchitis, or a blood pressure medication side effect. Figuring out which one applies to you depends on the other symptoms you may or may not notice.
Postnasal Drip Is the Most Common Cause
Postnasal drip, sometimes called upper airway cough syndrome, is the single leading cause of a persistent dry cough. It happens when excess mucus from your sinuses drips down the back of your throat, triggering your cough reflex. You might not even feel congested. Allergies, a lingering cold, sinus infections, and changes in weather or humidity can all keep this cycle going. The cough is often worse at night or first thing in the morning when mucus has pooled while you were lying down.
Acid Reflux Without Heartburn
Acid reflux can cause a stubborn dry cough even if you never feel heartburn. This happens through a condition called laryngopharyngeal reflux, where stomach acid travels past the esophagus and reaches the throat. Your throat tissues don’t have the same protective lining as your esophagus, so even a small amount of acid causes irritation. Those tissues also lack the mechanisms that wash reflux back down, meaning the acid lingers longer and does more damage.
In some cases, tiny acid particles pass through your windpipe into your lungs, especially during sleep. You won’t feel this happening. This silent aspiration can inflame your bronchial tubes and trigger a cough that seems completely unrelated to your stomach. Many people go months assuming their cough is from allergies or a cold before reflux is identified as the real culprit. A definitive diagnosis typically requires that the cough improves or disappears with anti-reflux treatment.
Cough-Variant Asthma
Most people picture asthma as wheezing and shortness of breath, but there’s a form where a dry cough is the only symptom. Cough-variant asthma involves the same narrowed, inflamed airways as classic asthma, but instead of making it hard to breathe, it makes you cough. There’s no wheezing, no chest tightness, nothing that feels like a typical asthma attack.
This makes it easy to miss. Your doctor may suspect it based on your history, especially if your cough worsens with exercise, cold air, or allergen exposure. Lung function tests like spirometry help evaluate how well your airways are working. Sometimes the clearest path to diagnosis is a trial of asthma medication: if the cough goes away, that’s strong confirmation.
Blood Pressure Medications
If you take a blood pressure or heart failure medication in a class called ACE inhibitors, it could be directly causing your cough. This is a well-known side effect that affects roughly 5% to 20% of people on these drugs, though some studies put the number as high as 39%. The cough is dry, persistent, and often described as a tickle in the throat. It can start within weeks of beginning the medication or develop months later, which makes the connection easy to overlook. Switching to a different type of blood pressure medication typically resolves the cough completely.
A Cough That Lingers After a Cold
If your dry cough started with a cold or respiratory infection and just won’t quit, you’re dealing with a post-viral cough. The infection itself is gone, but it left behind inflamed, hypersensitive airways that keep firing your cough reflex at the slightest provocation. A persistent post-viral cough typically lasts three to eight weeks, though in some cases it can stretch even longer. It resolves on its own without specific treatment for most people.
This is one of the most common reasons people search for answers about a dry cough. You feel fine otherwise, the cold is clearly over, but the cough hangs on for weeks. It can be frustrating, but it’s rarely a sign of something serious.
Less Common but Worth Knowing
Dozens of other conditions can produce a dry cough. Environmental irritants like smoke, dust, or chemical fumes trigger coughing in many people. Chronic bronchitis, typically linked to smoking, causes ongoing airway inflammation. Certain lung conditions, infections, and even stress can play a role. These are less likely explanations for the average person, but they matter if the more common causes have been ruled out.
Relieving a Dry Cough
Because a dry cough produces no mucus, the goal is to suppress the cough reflex itself rather than loosen anything in your chest. Over-the-counter cough suppressants containing dextromethorphan work by quieting the cough center in your brain. These are a reasonable short-term option for sleep disruption or daytime discomfort. Expectorants, which are designed to thin mucus, won’t help with a purely dry cough.
Longer-term relief depends entirely on the underlying cause. Treating allergies or sinus issues clears up postnasal drip. Managing reflux, sometimes with dietary changes and sleeping with your head elevated, addresses a reflux-related cough. Inhaler therapy controls cough-variant asthma. Switching medications resolves an ACE inhibitor cough. The cough itself is a symptom, so suppressing it without addressing the root cause only provides temporary relief.
Signs Your Cough Needs Medical Attention
A dry cough that lasts longer than a week or keeps getting worse warrants a visit to your doctor, especially if it’s accompanied by difficulty breathing, painful swallowing, wheezing, blood in any phlegm, or a high or persistent fever. These symptoms can signal something beyond the common causes and may need imaging or further testing to sort out. A cough lasting more than eight weeks is classified as chronic and almost always benefits from a structured evaluation to identify the specific trigger.