Iontophoresis and phonophoresis are drug delivery methods. They both involve medical devices and help topical medication absorb into your skin more effectively. Whereas iontophoresis uses electrical currents to do this, phonophoresis uses ultrasound waves to do it.

These methods appear most commonly in the physical therapy setting. Patients have benefited from iontophoresis to decrease pain, inflammation, and muscle spasms. In fact, it helps medications absorb into the skin up to 60 times more effectively than traditional topical medications. 

Phonophoresis has proven effective since the 1960s to treat sprains and strains in muscles, ligaments, and joints. Your physical therapist will apply a gel or cream corticosteroid or anesthetic to the site, then let ultrasound waves help your skin absorb it more effectively.