What is an interferential TENS unit?

interferential tens unit

An interferential TENS unit is an electrotherapy device that is able to deliver both interferential therapy (IF) and transcutaneous electrical nerve stimulation (though not at the same time). TENS and IF are not mutually exclusive but do not overlap either. For example, both waveforms are used for

·         Symptomatic relief of chronic intractable pain

·         Inflammation reduction

·         Post-traumatic acute pain and edema

·         Post-surgical acute pain and edema


 However, IF uses lower frequencies and penetrates deeper tissue than TENS. Discount Medical Supplies has several products that fit this description –whether it is a TENS/IF unit, or a device that also includes other waveforms like EMS, Microcurrent, or Russian Stim- such as:

·         InTENSity IF/TENS Combo

·         Quattro 2.5

·         InTENSity Select Combo 4-in-1

·         Twin Stim Plus 3rd Edition

·         CareTec IV TENS/EMS/IF/Russian Stim

·         ComboCare Ultrasound



Tens settings

IF settings

Treatment modes

Burst, normal, pulse width modulation, pulse rate modulation.

Four programs (P1, P2, P3, P4.)

Cycle time

(Optional, only modulation) 5-30 seconds.

5-30 seconds


Adjustable 1-60 minutes or continuous.

Pulse width

Adjustable 50-300us (microseconds).


Pulse rate

Adjustable 1-150 Hz (0,5-5 Hz for burst).


Interference frequency


(Optional, only P4) Adjustable 1-150 Hz.



Quattro 2.5



IF (IFC-4P, premodulated IFC-2P)

Treatment modes

10 programs


10-160 Hz


Pulse width



Amplitude modulation



Treatment times

15-20 minutes

15 minutes




Carrier frequency



Low beat frequency


5-130 Hz

High beat frequency


4-150 Hz


The ComboCare is nearly identical to the Quattro except that it can also deliver ultrasound therapy. The settings for the interferential TENS unit InTENSity Select Combo 4-in-1 are the exact same as those for the InTENSity IF/TENS Combo. The difference between those two devices is that the former also includes EMS and Microcurrent waveforms. The Twin Stim Plus 3rd Edition (like the Quattro 2.5 and CareTec IV) also provides four waveforms (substituting Russian Stim for Microcurrent), but its TENS and IF settings are ever so slightly different.


Twin Stim Plus 3rd Edition




Treatment modes

Burst, normal, modulation, strength duration 1, strength duration 2.

Normal, modulation, modulation 1.

Pulse width



Pulse rate

2-150Hz (0,5-5 Hz for burst).



1-60 minutes or continuous

Interference frequency




All of these devices, as well as other interferential TENS units such as the Ultima Neo, Winstim ST4U, and Winstim WSU come fully equipped with accessories like batteries, lead wires, electrode pads, and more.