What could be causing my persistent cough?

Q. I have had a persistent cough for six weeks. Otherwise, I feel okay. What may cause this?

A. People with a new cough lasting six weeks or longer should seek medical evaluation.

For current or past smokers, I order a chest x-ray even if their lung exam is normal. I might order a chest CT scan instead, depending on the person's age and number of pack-years of smoking. (Pack years = number of packs per day times the number of years they smoked.)

Even if you are a nonsmoker, many doctors would order a chest x-ray if a cough lasts six weeks.

Assuming you are a nonsmoker and your chest x-ray is normal, the most common causes of a persistent cough include:

Hypersensitive airways following a cold or bronchitis

Sometimes, people develop a prolonged cough long after a viral upper respiratory infection. Your body clears the virus. But the bronchial tubes stay inflamed.

Usual treatment: prescription inhalers.

Postnasal drip

This may be due to allergies, prolonged congestion after a cold, or a sinus infection.

Usual treatment: nasal irrigation, decongestants, and/or antihistamines.

Occult asthma

With this type of asthma, you may have little or no wheezing. Coughing is the main symptom.

Usual treatment: prescription inhalers

Acid reflux

Acid from the stomach can wash back into the esophagus. It then tends to move up higher to the throat. This irritates the tissue and prompts you to cough.

Usual treatment:

• not lying down for three hours after eating
• eating smaller meals
• noting which foods make the symptoms worse, and avoiding them
• acid blockers: An H2 blocker like nizatidine or a proton pump inhibitor such as omeprazole.

Cough caused by medicine

Some blood pressure medicines can also cause a constant throat tickle and cough. It's a common side effect of ACE inhibitors like lisinopril and enalapril.

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