TENS and Electrical Stimulation for Pain: How It Works and How to Use It

Applying electricity over painful areas is an ancient idea with a modern, evidence-based understanding. In Roman times, people believed electric eels placed in a shallow pool and allowed to "zap" a sufferer could cure pain — and there's even an ancient artifact some archaeologists suspect was an early battery used the same way. Today the principle survives in a small, safe, drug-free device called TENS.

How electrical stimulation relieves pain

Modern mild electrical stimulation is thought to reduce pain in one of two ways. First, the electrical stimulus competes for space on the same nerves that carry pain signals to the brain — the non-painful electrical sensation overrides the pain perception, effectively "closing the gate" on it. Second, electricity can trigger the release of the body's natural painkillers, endorphins — the same "runner's high" chemistry, and thought to be the primary mechanism behind acupuncture as well. Different frequencies and wave shapes favor one mechanism or the other.

What is TENS?

The most common device is TENS — transcutaneous electrical nerve stimulation. It's a small, pager-sized box worn on the belt, connected by a wire (a "lead") to sticky electrode pads placed on the skin. Good reusable pads can last up to a month. The device can be costly, but most insurance — including Medicare — approves it for chronic pain. Typically your pain physician rents you a unit for a month to see whether it helps; if it does, you can buy it or continue renting.

How to place the pads for best results

• Identify the area where it hurts most.
• Place two patches no more than a hand's width apart over the painful area.
• If you like, add two more patches so the pain is boxed in, with the current forming an "X" across it.
• Turn on the box.
• Turn up the intensity dial until it either becomes uncomfortable or the muscle twitches, then back off slightly. The stimulation should feel like a strong but comfortable tingling — it should not hurt, and no muscle should twitch.
• You may wear it up to about 8 hours a day on one area, adjusting the intensity up or down as needed through the day.
• Experiment with patch locations as your pain shifts — finding what works best for you is part of the process.
• If you find you need more and more intensity, check the battery and the patches; pads usually last two weeks to a month before they stop sticking well.
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Understanding the settings

Most good TENS units let you adjust two things under the cover — pulse width and pulse rate. It's worth understanding them, and worth discussing the right combination with your pain physician.

Pulse width is how long each pulse lasts, typically 40–250 microseconds. As you increase it, the sensation feels more spreading, deepening, and penetrating.

Pulse rate is how many pulses arrive per second (measured in Hz), usually adjustable from about 1 to 100. Comfort improves as the rate "matches" the nerves being treated. A low rate produces an acupuncture-like effect — helpful, but slower to relieve pain rather than instant.

Broadly, there are a few common treatment modes: a conventional mode (narrow pulse width, higher rate) that gives quick relief lasting up to a couple of hours; an acupuncture-like mode (wider width, low rate) that takes longer to work but can give longer relief; and burst and brief-intense modes for specific situations. Your physician can help you dial in the right mode for your pain.

Skin care and safety

Skin irritation under the pads is the most common problem, and it's preventable. Change pad locations after the first 24 hours and check for irritation. Keep the skin clean, make sure the wires are securely connected and not bent, don't run the unit longer than instructed, and rotate electrode sites. If a rash or sore develops, stop using the unit at that site and contact our office. You may shower or bathe with the pads on, but only with the wires and unit disconnected. Don't share your unit with anyone else.

TENS works best as one part of a complete pain plan, not a standalone cure. If your unit isn't giving relief, bring it in and we'll optimize the placement and settings with you. Call Newport Pain Management at (949) 759-8400.

This article is for general education and is not a substitute for individual medical advice.