E-stim deliberately passes electric current through the body. Done with proper equipment, in the right places, at sensible levels, the risks are small. Done carelessly, it can burn skin, injure muscle or, in the worst case, disturb the heart. This article sets out the hazards and the habits that keep them away.

It's general information, not medical advice. It can't assess your health, your unit or your setup. If in doubt, don't.

Who should not use e-stim#

Don't use e-stim, unless a doctor who knows your situation has told you it's safe, if you:

  • have a pacemaker, implanted defibrillator or any other implanted electronic device
  • have a heart condition or a heart rhythm problem
  • have epilepsy or a history of seizures
  • are pregnant

Take medical advice first if you have reduced sensation or nerve damage in the area, a blood clot or circulation problem, cancer, or metal implants near where the electrodes would go.

The main hazards#

Current through the heart#

This is the serious one. The heart runs on its own electrical signals, and outside current passing through the chest can upset its rhythm. That can happen at levels far below what's needed to cause a burn.

The defence is simple: never let the chest lie between two electrodes. Keep all electrodes below the waist, and never create a path from one arm to the other. See Where Electrodes Can and Can't Go.

Burns#

Skin burns happen when too much current passes through too small an area. The usual causes are a small electrode, a pad that's peeling or dried out, gel that's dried up, or running at a high level for too long. E-stim burns can be deceptive: the skin may look only slightly marked at first. See Contact Area and Current Density.

Muscle injury#

Strong contractions can strain muscles or cause cramp, just as overdoing exercise can. Keep levels moderate, especially at pulse rates that make muscles lock up.

Mains electricity#

A fault in anything connected to the mains can put dangerous voltage on the electrodes. Use battery-powered units, and don't use a unit while it's charging unless the maker says it's designed for that. See Batteries, Chargers and Mains Power.

Skin irritation#

Pad adhesive, gel, nickel in some metals, and one-way (unbalanced) current can all irritate skin. Stop if an area becomes sore or stays red.

Places current must never go#

  • the chest, or across it (including arm to arm)
  • the head, face and eyes
  • the front and sides of the neck
  • broken, irritated, sunburnt or numb skin
  • over piercings or jewellery, which concentrate the current

Equipment rules#

  • Use only units made for body contact, from a maker you can identify.
  • Use only electrodes made for e-stim. Use only purpose-made electrodes internally, and follow their instructions.
  • Check leads before each use. A broken wire makes the output cut in and out, and it comes back as a jolt.
  • Never use e-stim in the bath or shower, or with a unit that has got wet.
  • Don't build, open or modify a unit unless you have the training to do it safely.

Good habits#

  1. Unit off and level at zero before connecting or moving anything.
  2. Raise the level slowly. Sensation lags a little behind the dial.
  3. Turn down before changing mode, pulse rate or pulse width.
  4. Keep the controls within reach at all times, and be able to pull the leads out yourself.
  5. Stay awake and sober. Never fall asleep connected. Alcohol and drugs dull the pain that warns you something's wrong.
  6. Keep sessions short to begin with, and take breaks. Check the skin under the electrodes each time.
  7. With a partner, agree a clear stop signal first. The person feeling it has the final say, always.

When to stop#

Stop straight away if you feel:

  • pain, a sharp sting or a hot spot
  • chest discomfort, palpitations, breathlessness, dizziness or faintness
  • cramp that doesn't let go when the level drops

Turn the level down, switch off, then remove the electrodes.

Get medical help for chest pain, an irregular heartbeat, fainting, or any burn that blisters, is larger than a small coin, or doesn't improve in a few days. Tell them it was an electrical burn.