Good hydration supports treatment on two levels: appropriate internal fluid supply supports normal muscle and nervous system function, while external skin preparation reduces skin impedance under the electrode and makes the sensation of the current more comfortable.
Key idea
Well-hydrated skin has lower electrical resistance, so the same intensity feels more pleasant and distributes more evenly. Hydration is not the treatment itself, but improves the conditions for treatment: it enhances skin-electrode contact and supports pad longevity.
Why is hydration important? – Three levels
The body is roughly 60% water. This is not just a statistic: the spread of an electrical signal is fundamentally influenced by the volume of fluid compartments and the electrolytes dissolved in them (sodium, potassium, chloride). The effect can be interpreted on three levels:
The skin, with its outermost layer (the epidermis, particularly the stratum corneum), is the first barrier for an electrical signal. With dry, dehydrated skin this resistance (impedance) is substantially higher, which means the same set current intensity will be associated with a
The 2022 study by Goyal et al. (Sensors) directly examined how skin moisture and electrode material together significantly affect contact impedance.
Muscle contraction, conduction and regeneration are processes that require fluids. In dehydration, the effectiveness of electrical stimulation may decrease and the risk of cramp or unpleasant sensation during neural stimulation increases. Adequate fluid supply supports the conductivity of muscle fibers and comfort during treatment. This is especially important for EMS sessions or longer therapeutic courses.
Mitochondria—the cells' “power plants”—produce ATP, and this requires proper intra- and extracellular fluid compartments. Cell-level regeneration and transport processes will not work efficiently if the body is fluid-depleted. Microcurrent (MENS) is particularly sensitive to this because it targets these cellular mechanisms.
Internal hydration – what, how much, when?
Internal fluid supply should be maintained daily—the single glass right before treatment is not enough. Hydration tips for before and after electrotherapy are complements to daily routine, not substitutes.
| When | How much | What |
|---|---|---|
| Daily generally | 30 ml per kg body weight (≈ 2–2.5 L for an adult) | Water, weak tea, low-sugar drinks |
| 30–60 minutes before treatment | 200–300 ml water | Plain water, or electrolyte water if needed |
| During treatment | 100–200 ml water | Plain water—if the session is long (15+ minutes) |
| After treatment | 200–300 ml water | Fluid replacement, possibly an electrolyte drink after sport |
Caution – overhydration
Rehydration does not mean more is always better. Excessive water intake can lead to dilutional states (hyponatremia), especially during long sessions without electrolyte replacement. With chronic heart failure or kidney disease, fluid intake should always be agreed with the treating physician.
External skin preparation – under the pad
Alongside internal hydration, it is equally important that the skin under the pad is in the right condition. The 2017 Davies et al. (Skin Research and Technology) study found that skin moisture significantly affects electrical conductivity.
Step by step – skin preparation
- Clean the skin with lukewarm water and a neutral soap. Do not use alcohol wipes—they dry the skin.
- Pat dry with a soft towel. The skin should be moist but not dripping.
- If the skin is very dry (e.g. in winter or in older people), spray a fine water mist or apply a fragrance-free hydrating cream a few minutes before placing the pad (not oily or ointment-based!), then let it dry.
- Avoid cream residue on the pad area—the oily part of a cream can act as an insulator.
- With long hair—especially on the chest or thigh in men—consider shaving or trimming the area under the pad.
- Apply the pad evenly without air bubbles. Press for 5–10 seconds.
What NOT to put under the pad?
- Oily creams, ointments, petroleum jelly—insulating effect
- Alcohol or alcohol-based moisturizers—drying
- Salt water, iodine, disinfectants—chemical reaction with the pad
- Fresh sunscreen, perfumed body lotion—risk of allergic reaction
- Chemical cleaners on the pad surface
Hydration and pad lifespan
The adhesive layer of pads is sensitive to drying out and contamination. Proper hydration and skin preparation also extend pad lifespan.
| Factor | Effect on pad | Tip |
|---|---|---|
| Too dry skin | Doesn't stick well, peels off quickly | Place on hydrated skin |
| Too sweaty skin | Adhesive melts, slides off | Wipe dry before treatment |
| Creamy skin | Oil on the adhesive, reduced lifespan | Wait until cream is absorbed |
| Stubbly or hairy skin | Adhesive cannot reach the skin | Shave or trim the area |
| Proper skin preparation | 30–50 uses lifespan | See the skin preparation steps |
For details on pads and compatible electrodes see the article on electrotherapy electrodes. For polarity issues see the electrode polarity article.
Practical daily protocol
Hour before treatment
- 30–60 minutes before treatment drink 200–300 ml of water
- Clean skin with lukewarm water + neutral soap
- Pat dry with a soft towel
- If needed, a fine water spray or fragrance-free moisturizer a few minutes before pad placement
During treatment
- For longer sessions (15+ minutes) have 100–200 ml water available
- Continuously monitor the skin: if redness or stinging → reduce intensity
- If the pad adheres poorly: reduce intensity, stop the session, replace the pad
After treatment
- Remove the pad gently (stretch the skin slightly)
- Return reusable pads to their protective film
- Replenish 200–300 ml water
- After EMS training: support muscle recovery with a combination of protein + fluids
Frequently asked questions
Yes—both for comfort and for uniformity of treatment. The scientific literature (e.g. Goyal et al. 2022 and Davies et al. 2017) has shown that skin moisture significantly affects contact impedance. A 2015 study by Vance et al. also demonstrated that although impedance changes, TENS clinical effectiveness depends on other factors as well. So hydration is not a “magic formula”, but a factor that improves treatment conditions.
No, or only if it is fully absorbed. Oily creams and ointments form an insulating layer that hinders current flow and reduces pad adhesion. If you want to hydrate the skin before treatment, use a water-based, fragrance-free moisturizer and wait 10–15 minutes before applying the pad. Remove any cream residue from the treatment area.
A simple and effective solution: a fine water spray (as used for facial cleansing), or wiping with a slightly damp sponge 1–2 minutes before applying the pad. The skin should not be dripping, but lightly moist. If your skin is especially dry (e.g. in winter or due to age), you can apply a mild moisturizer 2–3 times daily in the treatment room (but not immediately before treatment).
In chronic kidney disease, severe heart failure, liver cirrhosis or other conditions affecting fluid balance, fluid intake is controlled by strict medical protocols. Do not increase intake on your own just because you are undergoing electrotherapy—agree the appropriate amount with your treating physician. Skin preparation rules (external hydration) still apply in these cases.
Lukewarm water is ideal. Hot water dries the skin and dilates capillaries, which is not beneficial for pad adhesion. Cold water does not dissolve oily residues well. Lukewarm (approx. 30–35°C) water with a neutral soap is a quick and effective solution.
Summary
A guide on how to prepare the skin and the body for TENS, EMS, microcurrent, IF and iontophoresis treatments—optimizing internal fluid intake and external skin hydration together.
Anyone performing home electrotherapy—whether for pain relief, muscle stimulation or cosmetic use. Particularly useful for athletes and older users.
Good hydration is a simple but often overlooked tool to improve treatment comfort and pad lifespan. Internally aim for about 2–2.5 L daily; externally clean with lukewarm water and use a fine water spray before pad placement if needed.
Learn about electrode polarity rules, electrode/pad selection, or the general safety information.
Scientific references
- Goyal K, Borkholder DA, Day SW. Dependence of Skin-Electrode Contact Impedance on Material and Skin Hydration – Sensors (Basel), 2022. PubMed: 36366209
- Davies L, Chappell P, Melvin T. Modelling the effect of hydration on skin conductivity – Skin Research and Technology, 2017. PubMed: 27873364
- Vance CG, Rakel BA, Dailey DL, Sluka KA. Skin impedance is not a factor in transcutaneous electrical nerve stimulation effectiveness – Journal of Pain Research, 2015. PubMed: 26316808
