phonophoresis /fō′nōfərē″sis/ , a therapeutic technique in which ultrasound waves are used to force topical medicines, such as hydrocortisone, aspirin, and lidocaine, into subcutaneous tissues. Continuous phonophoresis for up to 10 minutes can drive a drug applied to the skin surface about 5 cm into muscle tissue. Because of the risk that the patient may be hypersensitive to the medication, the technique is used with caution.
