The Comfee is a very safe device to use, however it shouldn't be placed on the following areas.- Face- Throat- GenitalsComfee or any TENS units are no suitable for anyone with a pace maker, and electrical implant or epilepsy. If at anytime during use you feel unwell or have any discomfort, please cease using and contact us for advice.If you have DVT, heart problems, epilepsy, cancer, or fragile skin, check with your doctor before using a TENS unit.Support@comfeerelief.com