Almost everyone can use it without the need for supervision. However, there are some exceptions. These include people with a cardiac pacemaker, ICD (implantable cardioverter-defibrillator), suspected or diagnosed heart problems (e.g. cardiac arrhythmia), seizure disorders (epilepsy), metal-containing intrauterine device (IUD), metallic implants, large skin lesions and lesions that cannot be covered with petroleum jelly, numbness in the treated areas, infections or irritated skin, impaired sensation in hands, underarms or feet (e.g. polyneuropathy), malignant disorders in the area of application, severe vascular disorders (e.g. local inflammation or thrombosis) and people who are pregnant.