Drinking apple cider vinegar on an empty stomach might cause nausea, acid reflux, or digestive discomfort for some people. It's recommended to dilute ACV with water or food to minimize potential side effects. Always start with small amounts to see how your body reacts before increasing intake.Drinking apple cider vinegar on an empty stomach might cause nausea, acid reflux, or digestive discomfort for some people. It's recommended to dilute ACV with water or food to minimize potential side effects. Always start with small amounts to see how your body reacts before increasing intake.