What is iontophoresis, and how does it differ from TENS or EMS?
Iontophoresis works with direct current (DC) – this fundamentally differentiates it from TENS, EMS or microcurrent (MENS), which all use alternating current (AC) biphasic pulses. An overview of the methods is presented in the electrotherapy methods pillar; this article specifically explains the mechanism of action of iontophoresis, its indications and practical application.
Key point
Iontophoresis is not an independent analgesic like TENS – the effect depends on the active substance used. Recent clinical evidence shows that local dexamethasone and lidocaine iontophoresis improved tennis elbow symptoms in a 24-patient double-blind trial [1]; magnesium sulfate iontophoresis significantly reduced neck pain in a 75-patient study [4]; and aluminum chloride hexahydrate gel iontophoresis significantly reduced palmar sweating in palmar hyperhidrosis [2]. The method is polarity-sensitive: the active substance must be delivered from the appropriately charged electrode – the electrode polarity article discusses this in detail.
How does the current deliver the active ingredient through the skin?
A 2021 literature review [5] states that iontophoresis promotes transdermal drug delivery via three different mechanisms:
This is the most fundamental mechanism: the electrode with the same charge "pushes" ions of the same charge toward the skin. A positively charged (cationic) drug (e.g. lidocaine, vitamin B1) is therefore driven from the anode (positive electrode), while a negatively charged (anionic) drug (e.g. dexamethasone, diclofenac) is driven from the cathode (negative electrode). With incorrect polarity, drug delivery can be markedly reduced or practically ineffective, because the electric field will not push the charged molecule inward but in the opposite direction. This is the most critical practical factor in iontophoresis. If the polarity of the preparation is unknown, swap the cables every 5 minutes during treatment. That way the treatment will work for at least "half the time."
At physiological skin pH (~7.4) the surface layers of the skin are slightly negatively charged. This means that during current flow the osmotic fluid movement (water flow) is directed from the anode toward the cathode – thus positively charged and neutral (non‑ionic) molecules applied at the anode are also "carried along" toward deeper skin layers. This is particularly important for delivering peptide and protein-like (often neutral) drugs [5].
Low-intensity current can temporarily modify the lipid structure of the stratum corneum, facilitating molecular penetration. This effect is reversible – after treatment the skin's barrier function returns. This mechanism explains why iontophoresis can deliver, to some extent, molecules that would not normally permeate the skin (e.g. larger-molecule anti-inflammatories). Important: this is not the same as electroporation, which uses high-voltage pulses and is applied mainly in research settings.
Clinical indications for iontophoresis
Clinical evidence since 2020+ shows measurable contributions of iontophoresis in the following areas. In each case it is used as an adjunct – alongside medical diagnosis and a treatment plan:
Primary palmar hyperhidrosis is one of the best-documented indications for iontophoresis. A 2021 systematic review [3] described iontophoresis treatment with approximately 81% symptomatic improvement in patients with hyperhidrosis. A 2024 32‑patient RCT [2] compared aluminum chloride hexahydrate gel iontophoresis to tap‑water iontophoresis: both groups showed a significant reduction in sweat rate (p < 0.001), with a larger effect size in the gel group. Detailed application is discussed in the hyperhidrosis spoke article.
A 2019 double‑blind trial of 24 patients [1] compared dexamethasone (4 mg/ml) + lidocaine‑gel iontophoresis to galvanic current alone. Both groups showed significant improvements in pain (movement and rest), grip strength and function (Patient‑Rated Tennis Elbow Evaluation). The dexamethasone+lidocaine iontophoresis group outperformed the galvanic current control in pain and function dimensions (p < 0.05). A 2020 umbrella review [6] mentions moderate evidence for iontophoresis among physiotherapy approaches to tendinopathies.
A 2024 randomized trial of 75 patients [4] compared magnesium sulfate (MgSO4) iontophoresis to high-power ultrasound and conventional physiotherapy for mechanical neck pain (active trigger points in the upper trapezius). Both MgSO4 iontophoresis and ultrasound produced significantly better results than conventional treatment in pain reduction, increased neck range of motion and functional improvement – the two active treatments were equivalent to each other.
Acetic acid iontophoresis is used as an adjunct treatment for heel spur (plantar fasciitis, calcaneal spur) – the acetate anion targets calcification tendencies. The 2020 tendinopathy‑focused umbrella review [6] lists iontophoresis as part of the physiotherapy toolkit. Detailed application and a heel‑specific protocol are described in the acetic acid iontophoresis for heel spur spoke article.
Delivering local anti‑inflammatory gels (containing diclofenac, piroxicam, ketoprofen, etc.) by iontophoresis is used as an adjunct for joint and soft tissue inflammations. The strength of evidence varies by indication – the most robust recent evidence is for tennis elbow [1] and neck pain [4]. The 2020 umbrella review [6] suggests iontophoresis is not the first‑line choice for tendinopathy (laser and shockwave have stronger evidence) but may contribute as an adjunct.
Polarity rules – which active ingredient from which electrode?
The most critical practical knowledge in iontophoresis is the polarity rule: the active substance must always be combined with the electrode that has the same charge (due to the repulsion principle). The table below summarizes the polarities of the most commonly used active substances:
| Electrode | Active substances | Typical indication |
|---|---|---|
| Positive (anode, +) | lidocaine, procaine, vitamin B1, calcium chloride, histamine | local anesthesia, muscle spasm relief |
| Negative (cathode, –) | dexamethasone, diclofenac, ketoprofen, salicylate, MgSO4, acetic acid | anti‑inflammatory effect, analgesia, local decalcification |
| Polarity‑independent (tap water, gel) | tap water, aluminum chloride hexahydrate gel | hyperhidrosis (sweat gland modulation) [2][3] |
The detailed polarity principle is available in the electrode polarity article. Never swap the electrodes: incorrect polarity not only makes the treatment ineffective, but may even produce the opposite effect.
Important – brand names vs. active substances
In the table I intentionally use active substance names (diclofenac, ketoprofen etc.), not commercial brand names (e.g. Voltaren, Fastum etc.). Any CE‑marked product containing the given active substance can be used. Selecting the specific drug and defining its concentration is an medical task – consult your treating physician or pharmacist.
How an iontophoresis treatment is performed – step by step
- Choice of active substance and polarity check. In consultation with the treating physician, select the appropriate active substance and determine from which electrode it should be delivered.
- Skin preparation. Wash the treatment area with lukewarm soapy water, dry thoroughly, and avoid creams and cosmetics.
- Placement of the active substance. Spread the drug solution or gel evenly on the sponge insert of the appropriate (same‑charge) electrode or directly on the skin under the electrode.
- Electrode positioning. Place the active electrode directly over the symptomatic area and the other (return) electrode on the opposite side of the targeted area (transverse placement) or distally (descending placement).
- Current intensity setting. Typically in the 0.5–5 mA range; clinical studies [1] used up to 5 mA. The sensation should be a pleasant tickling or slight warmth – reduce the current if the sensation is painful.
- Treatment time. Typically 15–20 minutes [1][4]; some hyperhidrosis protocols use 30 minutes.
- Treatment course. One treatment daily, a course of 10–15 sessions; for hyperhidrosis the 2024 RCT [2] applied the protocol every other day for 7 sessions.
- Finish. The device will stop automatically at the end of the timer. Remove the electrodes and wipe residual drug from the skin.
Home devices suitable for iontophoresis
Iontophoresis cannot necessarily be performed with classic TENS/EMS devices – a special direct current (DC) mode is required. In the MediMarket portfolio the following devices include factory iontophoresis programs:
- IontoBravo – a device specifically designed for iontophoresis, specialized for hyperhidrosis and local analgesia.
- Globus Genesy 3000 – 4‑channel multifunction device with factory MENS, TENS, EMS and iontophoresis programs.
- Globus Genesy 1500 – 2‑channel entry‑level multifunction device with basic programs.
Adhesive or sponge‑insert electrodes can be used for electrodes (adhesive or sponge electrodes) (a sponge insert soaked with the active solution retains liquid better).
When NOT to recommend iontophoresis treatment?
Iontophoresis contraindications fall into two groups: general electrotherapy contraindications (see: electrical treatment contraindications and electrical treatment and implants) and drug‑specific contraindications (allergy or contraindication to the chosen active substance).
- Pacemaker, ICD, implanted neurostimulator – only with permission from a cardiologist/arrhythmologist.
- Pregnancy – generally avoided for fetal safety reasons, especially when delivering drugs.
- Active malignant tumor in the treatment area – additional current over a tumor area is undesirable.
- Allergy or known sensitivity to the active substance chosen (e.g. lidocaine allergy).
- Fresh skin wound, extensive eczema, skin infection at the electrode site – the penetrating drug may produce systemic effects.
- Severe sensory disturbance in the treatment area – makes current intensity regulation difficult.
- Carotid sinus / anterior neck region – do not place electrodes near the carotid artery.
- Electrode positioned over the chest above the heart – risk of rhythm disturbances.
- Epilepsy with poorly controlled medication – individual assessment required.
- Metal implant directly under the electrode – risk of electrical heating.
For new, worsening or unexplained complaints always seek medical consultation before starting iontophoresis on your own. Always agree the active substance with your treating physician or pharmacist.
The place of iontophoresis within electrotherapy
Iontophoresis is a specialized modality – it does not replace other proven electrotherapy methods but complements them. The internal links below help position it in the offering:
- Electrotherapy methods – a comprehensive overview of methodologies.
- TENS – drug‑free analgesia – if nerve‑level analgesia without drugs is desired.
- Microcurrent (MENS) pillar – supporting cellular‑level regeneration with low current.
- Electrode polarity – detailed polarity principles for all electrotherapy methods.
- Hyperhidrosis (excessive sweating) – iontophoresis focus spoke.
- Acetic acid iontophoresis for heel spur – iontophoresis indication spoke.
Frequently asked questions about iontophoresis
Iontophoresis works with direct current (DC) and its primary aim is to deliver a drug through the skin. TENS works with alternating current (AC) biphasic pulses and aims at analgesia at the nerve level without drugs. The two methods have different goals and techniques – they do not replace each other, but both modes are often available on the same multifunction device (e.g. Globus Genesy 3000).
Clinical studies indicate effects are noticeable after 7–15 treatments. The 2019 tennis elbow RCT [1] measured significant improvement after 10–15 treatments; the 2024 hyperhidrosis RCT [2] recorded a statistically significant reduction in sweat rate after a 7‑session (every other day) protocol. In acute pain (anesthetic effect) analgesia may occur during the treatment, but lasting effects generally require 2–3 weeks of regular treatment. Individual results may vary.
No. Only ionizable (charged) molecules can be effectively driven by current, and only those able to cross the skin's stratum corneum. The 2021 review [5] lists characteristics of suitable molecules: molecular weight <500 Da, appropriate lipophilicity, and low melting point. Drug selection is a medical task – consult your treating physician or pharmacist. Do not experiment with inappropriate formulations for iontophoresis.
If you try to deliver the active substance from the wrong electrode (oppositely charged), the treatment will be ineffective – the drug may even be pulled back toward the skin surface. Therefore, knowing the polarity rule is critical in iontophoresis. The polarities of the most common active substances are in the table above; read the detailed principle in the electrode polarity article.
With direct current (DC), prolonged high‑intensity use can cause chemical skin irritation or mild burns – therefore proper current setting, adherence to treatment time (15–30 minutes) and use of an adequately moistened sponge insert/electrode are important. If you experience stinging, itching or any unpleasant sensation, immediately reduce the current or stop treatment. Inspect the skin under the electrode after every session.
Generally not – only with permission from a cardiologist/arrhythmologist. Any electrical treatment near active implants (pacemaker, ICD, neurostimulator) can cause interference. Detailed considerations are in the electrical treatment and implants article.
Summary – iontophoresis in brief
What everyone interested in iontophoresis should know
- Iontophoresis uses direct current (DC) to deliver active substances into subcutaneous layers – different from the alternating current operation of TENS/EMS.
- Polarity rule is critical: positive drugs (lidocaine, B1) are delivered from the anode, negative ones (dexamethasone, diclofenac, acetic acid) from the cathode.
- Recent clinical evidence: documented contributions in tennis elbow [1], primary palmar hyperhidrosis [2][3], and mechanical neck pain [4].
- Typical protocol: 0.5–5 mA, 15–20 minute treatments, once daily, 10–15 session course.
- Iontophoresis is an adjunct modality – it does not replace medical diagnosis or baseline pharmacotherapy.
- Home devices: IontoBravo (specialized), Globus Genesy 3000/1500 (multifunction).
- Contraindications (pacemaker, pregnancy, tumor, drug allergy, fresh skin wound) must be strictly observed.
- Selecting the active substance is a medical task – never experiment with non‑prescribed preparations.
Scientific sources (2019+)
The references [1]–[7] cited in the article refer to the following studies (number = ol‑list order):
- da Luz DC, de Borba Y, Ravanello EM, Daitx RB, Döhnert MB. Iontophoresis in lateral epicondylitis: a randomized, double-blind clinical trial. Journal of Shoulder and Elbow Surgery. 2019;28(9):1743-1749. PMID: 31447123.
- Majid Hosseini S, Ghandali E, Reza Moghimi H, Khademi-Kalantari K, Talebian Moghaddam S, Akbarzadeh Baghban A, Maryam Mortazavi S. A comparative evaluation of aluminum chloride hexahydrate gel iontophoresis versus tap water iontophoresis in people with primary palmar hyperhidrosis: A randomised clinical trial. Indian Journal of Dermatology, Venereology and Leprology. 2024;90(1):52-58. PMID: 37436009.
- Chudry H. The treatment of palmar hyperhidrosis – a systematic review. International Journal of Dermatology. 2022;61(11):1303-1310. PMID: 34653261.
- Ibrahim NA, Hamdy HA, Elbanna RHM, Mohamed DMA, Ali EA. Transdermal iontophoresis versus high power pain threshold ultrasound in Mechanical Neck Pain: a randomized controlled trial. Journal of Orthopaedic Surgery and Research. 2024;19(1):658. PMID: 39407315.
- Wang Y, Zeng L, Song W, Liu J. Influencing factors and drug application of iontophoresis in transdermal drug delivery: an overview of recent progress. Drug Delivery and Translational Research. 2022;12(1):15-26. PMID: 33486687.
- Girgis B, Duarte JA. Physical therapy for tendinopathy: An umbrella review of systematic reviews and meta-analyses. Physical Therapy in Sport. 2020;46:30-46. PMID: 32877858.
- Ghandali E, Hosseini SM, Moghimi HR, Khademi-Kalantari K, Talebian Moghadam S, Baghban AA, Mortazavi SM. Intra tester reliability of sympathetic skin responses in subjects with primary palmar hyperhidrosis. Journal of Bodywork and Movement Therapies. 2020;24(4):57-62. PMID: 33218563.
This article is for general informational purposes and does not replace a personal medical consultation. Selecting the active substance and determining its concentration for iontophoresis is exclusively a medical task. Contraindications (pacemaker, pregnancy, tumor, drug allergy, fresh skin wound) must be strictly observed. The devices shown are CE‑marked medical devices; the referenced clinical studies were carried out with various devices and protocols. Individual results may vary. For new, worsening or unexplained complaints, consult your treating physician or physiotherapist.
