Yes, thrush can extend into the esophagus. It could cause coughing and gaging. But thrush would be an unusual cause of a long lasting and persistent dry cough, especially if the persistent cough is the only symptom.

The three most common causes of a persistent, dry cough are:

• Post nasal drip
• Acid reflux
• Asthma

Still, I would not totally dismiss thrush as contributing to your cough.

Thrush is the commonly used term for a yeast infection in the mouth. The specific yeast is Candida.

Candida is all around us. It is common for a small number of colonies to grow on our skin and in our mouths. Candida can thrive under certain conditions, such as:

• When someone takes antibiotics for a long period of time
• When someone takes drugs that depress the immune system, such as corticosteroids (prednisone, prednisolone) or chemotherapy
• When someone has a medical condition that causes immune deficiency (such as HIV)

However, even people not on antibiotics and with normal immune systems can get thrush.

Most often, the yeast infection coats the tongue and back of the throat. Sometimes the Candida overgrowth will move into the esophagus and irritate the lining. When this happens, the person may have difficulty swallowing, painful swallowing and occasionally fever.

You and your doctor might decide to treat thrush with an antifungal mouth wash or an oral antifungal drug that you swallow (such as fluconazole).