Though ginger root generally does not cause side effects, high doses can cause diarrhea, mouth irritation or mild heartburn, according to University of Maryland Medical Center. When taken in supplement form or with a meal, ginger can reduce stomach side effects, such as gas or stomach upset.
Pregnant or breastfeeding women and individuals with gallstones, heart conditions or diabetes should consult with a doctor before taking ginger, explains University of Maryland Medical Center. Patients who take diabetes, high blood pressure or blood-thinning medications should also consult with a doctor before taking ginger. Ginger may lower blood sugar, reduce blood pressure and increase the possibility of bleeding.