What is iontophoresis?
Iontophoresis is a procedure in which an electrical current is passed through skin soaked in tap water or normal saline (0.9%), allowing ionised (charged) particles to cross the normal skin barrier. It reduces sweating and enhances the delivery of drugs and macromolecules into and through the skin. It is safe, effective and inexpensive.
What is iontophoresis used for?
The main use of iontophoresis is to treat focal areas of excessive sweating (hyperhidrosis), particularly on the palms or soles. Tap water iontophoresis is less effective in the axilla (armpit).
Limited robust data is available; however some studies suggested that up to 80-85% of patients with palmar hyperhidrosis notice subjective improvement in their symptoms within 2–4 weeks. One study showed that 33% of sole sites, and 37.5% of axillae sites had improved after 14 days, which increased to 78%, and 75% respectively over 20 days. Delivering antiperspirants or botulinum toxin A via iontophoresis has not been shown to be superior to tap water alone.
Iontophoresis has also been successfully used to deliver drugs to the skin in order to:
- Reduce sweating further using botulinum toxin A.
- Anaesthetise an area of skin with lidocaine.
- Treat fungal infection of nail plate (onychomycosis).
- Treat bursitis or tendonitis with anti-inflammatory drugs.
How does iontophoresis work in hyperhidrosis?
The mechanism of action of iontophoresis in reducing sweating is not completely understood. Sweat forms in response to an electrical gradient produced by sympathetic nerve activity on the cells of the sweat gland. There are several theories as to how a change in electrical gradient reduces sweat production.
- Ions produced by iontophoresis may physically block the sweat ducts in the stratum corneum.
- The external electrical current may disrupt normal sympathetic nerve transmission.
- The pH drops in the sweat gland due to an accumulation of hydrogen ions.
Iontophoresis for hyperhidrosis is usually carried out with ordinary tap water, however, an electrolyte solution or drugs (eg an anticholinergic agent such as glycopyrronium bromide) can be added if the water alone is not effective.
Procedure/what to expect
Battery-powered Direct Current (DC) and mains-powered Alternating Current (AC) devices are available. Individual machines vary, and the instructions provided by the manufacturer should be followed carefully.
For palmar hyperhidrosis, each hand is placed in a tray of water that contains the electrodes. It is recommended that petroleum jelly is applied to the skin at the water-line, and to any small cuts or wounds to prevent discomfort and localised inflammation. The device is switched on so that current passes through the water between the electrodes. The initial current should be very low, and then adjusted according to tolerance.
Initially treatment is undertaken for 20–30 minutes every 1–3 days until the desired effect is achieved, and then reduced to once per week to maintain the result. It is up to the patient to find what treatment regime works best for them long term to maintain results.
Side effects and risks of iontophoresis
Iontophoresis is generally a safe procedure. It is important to avoid direct contact with the electrodes during treatment, as it may cause a mild electric shock.
A feeling of pins and needles or burning sensation is experienced by most people. Adverse effects may include:
Although these side effects from iontophoresis are expected to resolve within a few days, emollients/moisturisers should be applied several times daily to reduce symptoms. Topical corticosteroids can be applied.
If used, anticholinergic drugs such as glycopyrronium may be absorbed into the body and produce systemic side effects such as dizziness, dry eyes and dry mouth.
Contraindications to iontophoresis
Iontophoresis should not be used by:
- Patients who are epileptic or have a history of seizures
- Patients with heart conditions or a pacemaker
- Patients with metal implants
- Pregnant woman
Patients should delay treatment if they have recent wounds, skin grafts, or scars in the area requiring treatment, as iontophoresis may be painful and the treatment less effective.