Whay causes a dry cough?

Lots of things: Inflammation of the mucosa of an airway below the vocal cords without actual disruption of the epithelial layer that lines it. Anything from a chest cold to acid stomach reflux while you sleep (this can be serious), to a popcorn hull that was forgotten to autoimmune disease to "coughing-type asthma" (which i have) to a lung cancer. If it lasts more than two weeks -- physician office visit.

Possibilities...: Cough, especially chronic cough, can be due to bronchospasm, gerd, post-nasal drip, bronchitis or even a combination of these etiologies. Bronchitic cough tends to be productive but the rest can be "dry." if one etiology is left untreated, the person will continue to cough. So, continue to see your doctor so all nessary treatments can be given to resolve your cough. Good luck!