Electrical stimulation is potentially harmful. It is contraindicated: in pregnancy; if the patient has a pace-maker; if there is lack of skin sensation; and in cases of impaired circulation, severe arterial disease, undiagnosed fever or severe skin lesions.

Careful monitoring of the electrical stimulation is recommended to prevent neural injury. Galvanic current should be used for only a very short period of time.

Low energy laser therapy may harm the eyes and both patient and operator should wear protective glasses.