Clinical library · Modalities
Interferential Current
Better than placebo when given alone. Repeatedly no better than sham when added to the exercise or rehabilitation the patient was going to receive anyway — which is how it is almost always used.
In one line. Two medium-frequency alternating currents applied through crossed electrode pairs, interfering to produce a low-frequency beat inside the tissue. The rationale is that medium-frequency current crosses skin impedance more comfortably than the low-frequency current used in TENS.
The evidence divides cleanly along one line, and it is the line that matters in clinic: against nothing, it works; against sham, added to a real rehabilitation programme, it mostly does not.
The distinction to hold onto. A meta-analysis of 35 trials, 19 pooled, found that interferential current alone versus placebo demonstrated a significant pain-relieving effect — but showed no significant difference when added to standard treatment compared with placebo plus standard treatment or standard treatment alone, and no significant difference against other single interventions including laser, TENS and cryotherapy. Its authors add that the low number of studies raises suspicions even about the positive finding. [2]
What the evidence shows
| Question | Finding | Source and quality |
|---|---|---|
| Versus placebo, chronic non-specific low back pain | Pain -1.57 points (95% CI -2.17 to -0.98); disability -1.51 (-2.57 to -0.46), immediately post-treatment | 13 RCTs, pooled n = 1,367. Moderate-quality evidence, moderate effect size — but not at intermediate-term follow-up [1] |
| Versus TENS | SMD -0.32 (95% CI -0.61 to -0.03) for pain immediately post-treatment; no difference for disability | Low-quality evidence, small effect [1]. A separate review found no significant difference against TENS, laser or cryotherapy [2] |
| Added to massage or exercise | May not further reduce pain or disability | Very low-quality evidence [1] |
| Added to standard treatment | No significant difference | Against placebo plus standard treatment, or standard treatment alone [2] |
| Knee osteoarthritis, plus exercise vs sham plus exercise | Differences at week 3 were statistically significant but all below the minimal clinically important difference; no differences at week 6 | Mean differences 0.76 (NRS pain), 0.49 (WOMAC total), 0.63 (WOMAC pain), 0.62 (WOMAC stiffness). Authors conclude no effect [3] |
| Added to rehabilitation after proximal humeral fracture | No significant difference between interferential and sham | Both groups improved significantly over time on all measures [4] |
| Added to exercise in neck pain | Better immediate outcomes across pain, disability and psychological measures | A positive trial, and the outcome is immediate rather than sustained [5] |
Where it misleads
1. "Better than placebo" is not the clinical question
Nobody offers interferential current instead of rehabilitation; it is offered alongside it. The placebo comparison answers a question no clinician faces. The add-on comparison — interferential plus exercise against sham plus exercise — is the relevant one, and it has returned null results in knee osteoarthritis [3] and after proximal humeral fracture, [4] and no significant difference when added to standard treatment across a 35-trial review. [2]
2. Statistically significant is not clinically important
The knee osteoarthritis trial is the clearest illustration on this site of the distinction. At week 3 the interferential group was statistically better on four measures — and every one of those mean differences was below the minimal clinically important difference for that measure. By week 6 there were no differences at all. The authors' conclusion is that it had no effect on pain or function. [3] A page reporting only the week-3 p-values would be technically accurate and thoroughly misleading.
3. The benefit that does exist is immediate and does not last
The low back pain review found moderate-quality evidence for pain and disability reduction immediately post-treatment and explicitly not at intermediate-term follow-up. [1] The positive neck pain trial reports better immediate outcome. [5] For a chronic condition, an effect that is gone by the next follow-up is a limited claim.
4. It is not meaningfully different from TENS
Against TENS the difference in pain was a standardised mean difference of -0.32 on low-quality evidence, with no difference in disability, [1] and a separate review found no significant difference against TENS at all. [2] The comfort argument for medium frequency may hold; a claim of superior effect does not.
What the evidence supports — and what it does not
Supported
- Short-term pain and disability reduction against placebo in chronic non-specific low back pain, on moderate-quality evidence. [1]
- A pain-relieving effect when used alone against placebo. [2]
- Immediate improvement when added to exercise in neck pain, in one trial. [5]
Not supported
- Adding it to standard treatment. No significant difference. [2]
- Adding it to exercise in knee osteoarthritis. Differences below the MCID at 3 weeks, none at 6. [3]
- Adding it to rehabilitation after proximal humeral fracture. No difference from sham. [4]
- Lasting benefit. Not present at intermediate-term follow-up. [1]
- Superiority over TENS, laser or cryotherapy. [1][2]
How certain is this?
Evidence grade: Low to moderate.
The strongest single finding — short-term benefit over placebo in low back pain — carries the review authors' own grading of moderate quality, from 13 trials and 1,367 participants. [1] Everything weaker than that in the same review is explicitly labelled low or very low quality.
The larger review covered 35 trials of variable methodological quality assessed against 39 criteria, and its authors caution that the low number of studies raises suspicions about their own positive conclusion. [2] That is unusual candour and this page takes it at face value.
The two null add-on trials are single randomised sham-controlled studies, [3][4] and the one positive add-on trial is likewise a single study reporting immediate outcomes. [5] The pattern across them is more informative than any one.
What would change the grade: adequately powered sham-controlled trials of interferential current added to a defined exercise programme, with follow-up beyond the end of treatment.
Common questions
Should I add interferential current to an exercise programme?
The evidence does not support expecting it to add anything. A 35-trial review found no significant difference when interferential current was added to standard treatment compared with placebo plus standard treatment or standard treatment alone. [2] In knee osteoarthritis, adding it to exercise produced week-3 differences that were all below the minimal clinically important difference and no differences at week 6. [3] In proximal humeral fracture rehabilitation, it did not differ from sham. [4]
Is it better than TENS?
Not demonstrably. One review found a small effect favouring interferential for pain immediately post-treatment (SMD -0.32) on low-quality evidence, with no difference in disability; [1] another found no significant difference against TENS, laser or cryotherapy. [2] See electrotherapy and passive modalities for the TENS evidence.
Does it work for low back pain?
Against placebo, immediately after treatment, yes: pain -1.57 points and disability -1.51 on moderate-quality evidence across 13 trials and 1,367 patients. The same review found the effect was not present at intermediate-term follow-up, and that adding it to massage or exercise may not further reduce pain or disability. [1] See low back pain.
Is there any situation where it is clearly worth using?
The honest answer from this evidence is: as a short-term analgesic when used alone, in a patient who is not yet able to engage with active treatment. That is a narrow indication, and it is not how the modality is usually deployed.
References
- Rampazo ÉP, Júnior MAL, Corrêa JB, et al. Effectiveness of interferential current in patients with chronic non-specific low back pain: a systematic review with meta-analysis. Brazilian Journal of Physical Therapy. 2023 Sep-Oct;27(5):100549. doi:10.1016/j.bjpt.2023.100549 PMID 37801776 Systematic review and meta-analysis
- Hussein HM, Alshammari RS, Al-Barak SS, et al. A Systematic Review and Meta-analysis Investigating the Pain-Relieving Effect of Interferential Current on Musculoskeletal Pain. American Journal of Physical Medicine & Rehabilitation. 2022 Jul 1;101(7):624–633. doi:10.1097/PHM.0000000000001870 PMID 34469914 Systematic review and meta-analysis
- Varapirom C, Kuptniratsaikul V, Yamthed R, et al. Efficacy of interferential current therapy plus exercise compared to sham interferential current plus exercise for pain relief in patients with knee osteoarthritis: A randomised controlled trial. Clinical Rehabilitation. 2024 Dec;38(12):1622–1632. doi:10.1177/02692155241278949 PMID 39257067 Randomised sham-controlled trial
- Duran E, Durmaz B, Atamaz FÇ, et al. Does interferential current provide additional benefit to orthopedic rehabilitation for the patients with proximal humeral fractures? A randomized controlled study. BMC Musculoskeletal Disorders. 2024 Feb 7;25(1):114. doi:10.1186/s12891-024-07232-4 PMID 38326840 Randomised controlled trial
- Albornoz-Cabello M, Pérez-Mármol JM, Barrios Quinta CJ, et al. Effect of adding interferential current stimulation to exercise on outcomes in primary care patients with chronic neck pain: a randomized controlled trial. Clinical Rehabilitation. 2019 Sep;33(9):1458–1467. doi:10.1177/0269215519844554 PMID 31007047 Randomised controlled trial
About this resource
Using this in clinic
Every figure here is traceable to its source.
This page separates the placebo comparison from the add-on comparison throughout, because only the second answers the question a clinician actually faces. Where a value could not be verified against the paper it came from, it is not on this page, and the omission is stated rather than filled with a number from a secondary source.