The 5 Most Common Causes of a Nagging Cough — and When You Should Really See a Doctor

tissue box, thermometer, and flu medication
Dr. Sharon Orrange
Dr. Orrange is an Associate Professor of Clinical Medicine in the Division of Geriatric, Hospitalist and General Internal Medicine at the Keck School of Medicine of USC.
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A nagging cough is one of the most common reasons why people schedule a doctor’s visit, especially during cold and flu season. It’s just a cough with no other symptoms — no runny nose, no headaches — but it won’t go away. Could it be lung cancer? Tuberculosis? Here’s what may be causing your cough and when you should really see a doctor.

What is a persistent dry cough?

A nagging cough is often a persistent dry cough, one that’s mostly annoying (where you aren’t coughing up much junk) and has been around for more than three weeks. Dry cough is often the symptom that hangs on after the rest of your cold or flu symptoms have resolved. Here’s a cool fact: women tend to cough more than men because the nerves responsible for cough reflexes in women are more sensitive than they are in men. 

What are the most common causes?

To narrow down what may be causing your cough, first ask yourself these two questions:

  1. Am I a smoker now or was I in the past?
  2. Have I had a chest x-ray done? If so, was there anything wrong with it? Coughs lasting more than eight weeks should be evaluated by a doctor and a chest x-ray should be performed.

If you answered “no” to both of these questions, 99.4% of the time, one of the following reasons is behind your cough:

1) Reactive Airway Disease after a Cold or Flu

At the end of cold and flu season, this is the most common cause of lingering dry cough. It occurs after an acute upper respiratory illness like a cold and though it may linger, it will resolve without specific therapy. Airway inflammation after infection causes them to be hyper-responsive and twitchy, making you cough.

2) Post-Nasal Drip (aka. Upper Airway Cough Syndrome) 

Post-nasal drip syndrome, which often comes with chronic rhinitis, is now known as “upper airway cough syndrome”. Hints that this may be the cause of your cough: the sensation of liquid dripping down the back of your throat, throat clearing, and nasal discharge. Over-the-counter nasal sprays like Flonase (fluticasone) or Nasacort may help solve that.

3) Asthma with Cough (aka. Cough-Variant Asthma)

The second leading cause of a persistent cough in adults is called “cough-variant asthma.” Hints here: it may follow an upper respiratory infection, and worsen with exposure to cold or certain allergens (dust, certain fumes). If your doctor suspects this, an oral inhaler will be part of the solution.

4) Acid Reflux or GERD

Acid reflux or gastroesophageal reflux disease (GERD) is a common cause of persistent dry cough. Know that for many people, cough due to reflux will NOT come with heartburn or a sour taste in your mouth. A two-week course of Prevacid (lansoprazole), Protonix (pantoprazole), Prilosec (omeprazole), or Nexium (esomeprazole) may solve your cough if this is the cause.

5) Medication Side Effect

ACE inhibitor medications are well-known culprits of a persistent dry cough. ACE inhibitors are a group of drugs that treat high blood pressure, heart disease, diabetes, and other diseases. Popular ACE inhibitors include lisinopril (Prinivil, Zestril), benazepril (Lotensin), captopril (Capoten), and enalapril (Vasotec). A cough will usually resolve within 1-4 days of stopping your medication if that is the cause.

What is NOT a likely cause of persistent dry cough?

Here are the dangerous things patients often worry about when they have a cough that doesn’t go away — and here’s why you probably don’t need to lose sleep over them:

Lung Cancer

In all cases of persistent coughs, lung cancer is the cause in less than 2% of them. A history of smoking is the biggest risk factor for lung cancer. Weight loss, difficulty breathing, coughing up blood — these are the serious warning signs of lung cancer (not a cough).

Pulmonary Embolism (PE)

A pulmonary embolism (PE) is when a blood clot in the deep veins of your legs dislodges, travels up your body, and gets stuck in your lungs. It will cause difficulty breathing, shortness of breath, and chest pain. If you just have a dry cough, that’s very very unlikely to be a sign of PE.

Tuberculosis (TB)

Cough can be one of the symptoms of lungs infected with tuberculosis (TB), but you won’t get that alone. If you have TB, you’ll also likely have night sweats, sudden weight loss, and low-grade fevers — you won’t feel good at all.

Final note: if you have a cough along with fever, shortness of breath, chest pain, weakness, and/or nausea and vomiting, it is NOT a persistent dry cough. That’s a different story. See your primary care doctor if this is the case.

Dr O.

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