Therapeutically, electromotive drug administration (EMDA) delivers a medicine or other chemical through the skin. In a manner of speaking, it is an injection without a needle, and may be described as non-invasive. It is different from dermal patches, which do not rely on an electric field. It drives a charged substance, usually a medication or bioactive agent, transdermally by repulsive electromotive force, through the skin. A small electric current is applied to an iontophoretic chamber placed on the skin, containing a charged active agent and its solvent vehicle. Another chamber or a skin electrode carries the return current. One or two chambers are filled with a solution containing an active ingredient and its solvent vehicle. The positively charged chamber, called the cathode, will repel a positively charged chemical species, whereas the negatively charged chamber, called the anode, will repel a negatively charged species into the skin.
Common diagnoses treated with iontophoresis include plantar fasciitis, bursitis, and some types of palmar-plantar hyperhidrosis.
Iontophoresis is commonly used by physical therapists and occupational therapists for the application of anti-inflammatory medications such as Dexamethasone.