Iontophoresis is a way to get a drug deep into your body by the use of electricity. The two drugs most commonly used are 4% Lidocaine and .4% Dexamethasone. The treatment takes 10 to 20 minutes. During the treatment you may feel a slight tingling sensation.  The process is that your prescribed drug is injected onto a buffer pad, the same polarity of current is then place on the pad containing the drug.  Once the current begins, the two like polarity want to repeal each other, so the medication in the pad is forced through the skin without causing any open skin penetrations.  Treatment area remain only as large of the buffered pad in which the drug was injected, so you must have localized area of treatment.