Quick answer: A TENS machine works by sending gentle electrical pulses through electrode pads placed on your skin. The pulses do two things: they stimulate the nerves that carry touch signals, which blocks pain signals from reaching your brain, and they trigger the release of endorphins, your body's natural painkillers. The effect builds the longer you use it, which is why starting early matters, especially in labour.
The two ways TENS relieves pain
TENS stands for Transcutaneous Electrical Nerve Stimulation, and it relieves pain through two mechanisms working together.
The first is known as the Gate Control Theory of pain, first described by researchers Melzack and Wall in 1965. Your nervous system can only carry so many signals to the brain at once. The mild electrical pulses from a TENS machine stimulate the large nerve fibres that carry touch sensations, and those signals effectively crowd out the pain signals travelling along smaller fibres. The "gate" to the brain closes on the pain.
The second mechanism is chemical. The stimulation prompts your body to release endorphins, its own natural pain-relieving compounds. Endorphin levels build the longer the stimulation continues, which is why TENS relief compounds over time rather than working instantly like a tablet.
This combination has kept TENS in clinical use for over 50 years, for everything from back pain and period pain to arthritis and sports recovery. If you are starting from scratch, our guide What is a TENS machine? covers the basics.
What do the pulses feel like?
A tingling or gentle buzzing on your skin, similar to pins and needles. You control the intensity completely: start low, then increase until the sensation feels strong but comfortable. It should never hurt. If it does, you simply turn it down.
How TENS works during labour
Labour is where TENS shows its full design. An obstetric TENS machine like the Elle TENS 2 applies the same two mechanisms with features built for contractions:
- Continuous mode between contractions keeps a steady baseline of stimulation, building endorphins as labour progresses.
- The Opti-Max boost button switches to a stronger pattern at the peak of each contraction, closing the pain gate hardest exactly when you need it.
- A contraction timer helps you and your birth partner track how labour is progressing.
The electrodes sit on your lower back, over the nerves that carry contraction pain, and nowhere near your baby. Starting TENS at the first regular contractions gives your endorphins the longest time to build, which is why mums who start early often report needing less additional pain relief later. For choosing a device, see What is the best TENS machine for labour in Australia?
Using a TENS machine well
A few simple practices get the best from any TENS machine. Attach the pads before switching the unit on, and position them either side of the painful area (for labour, your hire includes a placement chart showing the correct lower back positions). Avoid placing pads on the front or sides of your neck, your temples, near your eyes or mouth, on broken or irritated skin, or over varicose veins. Switch the unit off before removing the pads, and store reusable electrodes on their paper backing to preserve the gel.
TENS should not be used in water or while driving. People with a pacemaker or another implanted electrical device, epilepsy, or a heart condition should seek medical advice before using TENS. During pregnancy, TENS is well established for labour itself; for other pain earlier in pregnancy, check with your midwife or doctor first.
Does the science back it up?
Yes. The Gate Control Theory is one of the most cited frameworks in pain science, and TENS specifically has been studied extensively in labour. A Cochrane systematic review of 17 randomised trials covering 1,466 women found no adverse events for mothers or babies, and most women using TENS said they would choose it again for a future labour. For the safety evidence in detail, see Is a TENS machine safe for my baby during labour?
Why Elle TENS
Elle TENS machines are made by Body Clock Healthcare, who invented the world's first obstetric TENS machine in the early 1990s and have refined the technology for over 30 years. More than one million mums have used them globally. In Australia they are registered on the ARTG (number 225921) and supplied with Babycare-certified maternity electrodes sized and calibrated for the device. You can hire the Elle TENS 2 for your birth or buy the Elle TENS Plus to keep.
Frequently Asked Questions
How does a TENS machine stop pain?
Two ways at once. The electrical pulses stimulate touch nerves that block pain signals from reaching your brain (the Gate Control Theory), and the stimulation triggers endorphins, your body's natural painkillers. The two effects work together and build over time.
How long does a TENS machine take to work?
The gate control effect begins within minutes, while the endorphin effect builds the longer you use it. This is why starting TENS early, at the first regular contractions in labour, gives the best results as intensity increases.
Does TENS work for labour pain?
Yes. TENS has been used in obstetric care for decades, and obstetric devices like the Elle TENS 2 add a boost button for contraction peaks and a contraction timer. A Cochrane review found most women using TENS in labour would choose it again, with no adverse events for mother or baby.
What does the Opti-Max boost button do?
Pressing the boost button at the start of a contraction switches the stimulation to a stronger, continuous pattern that maximises the gate control effect during the peak. When the contraction eases, you switch back and the device returns to building endorphins between contractions.
Does a TENS machine work for back pain or period pain?
Yes. The same two mechanisms apply to most types of pain, which is why TENS is widely used for back, neck and joint pain, period pain, arthritis and sports recovery. Pad placement simply moves to either side of the painful area.
Can a TENS machine be harmful?
TENS is non-invasive, drug-free and widely considered safe. The sensible precautions: seek medical advice first if you have a pacemaker, implanted device, epilepsy or a heart condition, do not use TENS in water or while driving, and follow the pad placement guidance in your instructions.
Sources
- Melzack R, Wall PD. Pain mechanisms: a new theory. Science. 1965;150(3699):971-979.
- Dowswell T, Bedwell C, Lavender T, Neilson JP. Transcutaneous electrical nerve stimulation (TENS) for pain management in labour. Cochrane Database of Systematic Reviews 2009;(2):CD007214.
