Interferential current (IFC)

Interferential current is essentially a deeper form of TENS. In essence, IFC modulates a high frequency (4000 Hz) carrier waveform with the same signal produced by a TENS unit. The high frequency carrier waveform penetrates the skin more deeply than a regular TENS unit, with less user discomfort for a given level of stimulation. Deep in the tissues, the carrier waveform is cancelled out, resulting in a TENS-like signal deep under the skin.

Anecdotal evidence suggests that the IFC units may be useful for patients who have not had relief from TENS. However, at $2000 per unit, IFC devices are significantly more expensive than TENS units.