Is it possible to get acid reflux from taking Zyrtec on a empty stomach? When I take it with food it's been okay.

Not reflux, but could be an indication of irritation/inflammation of the lining of the esophagus or stomach. Chasing the dose with a glass of water and with food in the stomach would minimize this. If the discomfort is frequent, be sure to discuss with your doctor and check labels for any otc medications that can worsen the problem.