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Many brands offer transcutaneous electrical nerve stimulation (TENS) units that can help reduce pain. They are suitable for people with sciatica, arthritis, and fibromyalgia. However, they may not be safe for people who are pregnant or have other conditions.

This article describes what TENS units are and explores some products available to buy online. It also lists some considerations a person should make before purchasing and answers frequently asked questions about TENS units.

Medical News Today chooses TENS units based on the following criteria where possible:

  • Price: MNT chooses products available for a wide range of budgets.
  • Brand reputation: MNT chooses brands that adhere to industry best practices and that offer reliable customer service and support.
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Please note that the writer of this article has not tried these products. All information presented is purely research-based and correct at the time of publication.

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The table below compares each TENS machine for price, the number of settings, and their advantages and disadvantages.

Price Who it is best forNumber of modesProsCons
Therabody$349people who want support during use12• personalized setting suggestions
• comes with app
• discreet
price is high compared to other products
Healthmate Foreveraround $100people who want massage simulation15• includes range of massage types
• lifetime warranty
• not rechargeable
• more expensive
iRelievaround $190people needing pain relief on the go14long warrantyprice is high compared to other products
HiDowaround $119people needing short-term pain relief4• rechargeable
• wireless
• portable
• large surface area
maximum of 4 modes
TENKERaround $40people on a budget24• affordable
• rechargeable
• 24 modes
users report poor electrode quality
Omronaround $39people with foot pain10• preset programs for targeted pain relief
• affordable
• portable
• discreet size
• fewer modes than other units
• comes with one pair of electrodes
Oviraaround $140people with period painnot stated• discreet
• suitable for period pain
• portable
• health insurance covered
• all-day battery life
has one massage or vibration mode
AUVONaround $38people wanting dual channels20 intensity, 24 massage• pocket-sized and portable
• affordable
• three color options
reviewers mention receiving faulty devices and that the machine gives off electric shocks
TechCarearound $37people wanting a lifetime warranty24• has FDA approval
• comes with both small and extra-large pads
• affordably priced
• lifetime warranty
reviewers mention needing to sign up for the warranty, poor customer service, and receiving faulty devices

TENS is a noninvasive pain relief management device. It sends a mild electrical current through electrodes attached to the skin.

Electrical muscle stimulation (EMS) is a physical therapy and fitness technique that also uses electrodes to transmit electrical impulses.

A TENS unit comes with:

  • a battery-powered generator
  • a single or dual channel
  • lead cables
  • sticky patches, or electrodes

A person places the electrodes on or around the painful area. The TENS device stimulates the nerve endings to produce endorphins to reduce pain. Endorphins block the brain’s transmission of pain signals.

Learn more about TENS.

Doctors may recommend using a TENS unit for acute and chronic pain that results from surgery and other health conditions, including:

A 2020 study reviewed the effects of a 4-week TENS treatment in women with fibromyalgia. Researchers found significant improvements in movement-evoked pain and fatigue.

A 2021 study also noted that TENS therapy provided immediate pain relief in people with chronic low back pain.

According to another 2021 study, TENS units are safe for people with endometriosis and menstrual cramps, as they can alleviate pain and manage primary dysmenorrhea.

Also, one 2020 review of 26 studies found that TENS can significantly reduce pain during labor.

Using TENS is generally safe and does not have side effects. However, the adhesive pads can cause allergic reactions, but special nonallergic pads are available.

TENS can also cause metallic or electronic implants, such as defibrillators and cardiac pacemakers, to malfunction.

A person should not use TENS machines while driving, operating machinery, or while in contact with water, such as bathing, showering, or swimming.

A person should never place TENS pads on the following areas:

  • temples
  • front or sides of the neck
  • mouth
  • eyes
  • numb skin
  • irritated or broken skin
  • varicose veins
  • the chest and upper back simultaneously

Also, people with any of the following conditions should not use TENS units:

TENS is safe during pregnancy, but a person with a history of early miscarriage or a previous abortion should not use TENS while pregnant.

If a person has had complications in their current pregnancy, they should not use TENS.

A person should be careful when placing the TENS electrodes during pregnancy. Putting them in certain locations can cause labor contractions. These areas include:

  • web space between thumb
  • lower half of the leg or ankle
  • top of the shoulders

If a person develops labor contractions while using TENS, they should immediately turn off the machine and speak with a doctor.

A person must always follow the manufacturer’s instructions and stop using a faulty TENS machine that makes pain worse or causes skin reactions.

People should consult a doctor or physical therapist to determine how and when to use a TENS unit.

TENS units can be used daily. A person should start on a low setting and gradually increase it to find the right intensity.

A person can use them to help ease pain from a wide range of conditions, including:

Generally, a person will place the pads at least 1 inch apart on the painful area.

If a person experiences side effects from using a TENS machine, they should stop using it and contact a doctor.

TENS units can provide pain relief with few to no side effects.

However, a person should speak with a doctor before using a TENS unit. A medical professional can diagnose the cause of a person’s pain. They can advise on whether a TENS machine will be a safe and suitable method of pain relief.

TENS machines are not safe for everyone. People should not use TENS machines without speaking with a doctor first if they:

Learn more about TENS for overactive bladder.

If a person develops skin irritation from the pads, they should stop using the TENS machine and speak with a doctor. There may be hypoallergenic pads available.

Features to consider when choosing a TENS unit include:

  • Treatment modes: Units with various treatment modes allow a person to choose a mode that offers relief for a specific body area.
  • Intensity levels: These allow the user to adjust the unit’s power based on their tolerance. Digital adjustments offer more graded control than dials or knobs.
  • Portability: Some devices have a small and lightweight design. These might suit people who wish to use the product while working.
  • Timer: Many devices come with preset timers, while others feature an adjustable timer. Most machines also come with an auto shut-off feature.
  • Channels: TENS units with dual channels allow people to use each channel with different modes and intensities.
  • Power source: Some devices use rechargeable batteries, while others use disposable ones. A person should consider how long a full charge can last if they use it continuously and how cost-effective units will be if they need to replace batteries regularly.
  • EMS: Some TENS units have EMS functions as well. EMS may help strengthen and stimulate muscles and may be ideal for rehabilitation and improving sports performance. A 2020 study found EMS effective in improving the quality of life and physical outcomes in people with advanced stages of cancer.

Below, we answer some of the most frequently asked TENS unit questions.

What is the difference between TENS and EMS?

While TENS and EMS apply electrical currents in the body, TENS aims to relieve pain. EMS contracts the muscles and is suitable for rehabilitation and strength performance.

Does TENS hurt?

Typically, TENS does not hurt. However, people will have different thresholds regarding how comfortable they find higher-intensity TENS settings.

A person should start using lower settings and gradually work up, only using an intensity level with which they are comfortable.

Does TENS help sciatica?

TENS may relieve a person’s discomfort from sciatica pain and help them regain mobility to perform daily activities.

Is TENS safe?

TENS is a noninvasive, nonaddictive pain relief option that does not cause any side effects.

Are TENS units worth it?

TENS units can be an effective and affordable method of pain relief, depending on the TENS machine a person chooses. Additionally, research has found TENS to have few to no side effects.

A person should speak with a doctor to determine whether a TENS machine will be effective for their pain.

Which TENS mode is best?

TENS machines offer different features. A person may wish to consider purchasing one with different modes to find the setting that works best for them.

What is the disadvantage of TENS?

People may think that TENS can cause damage to the nerves. However, they should consult with a doctor before using a TENS unit for the first time and notify them if they experience any side effects.

Is there a difference between TENS machines?

TENS machines are available for different budgets and conditions, such as foot pain, period pain, and nerve pain.

They also have a portable design, a controller, and a rechargeable battery.

One can also consider the intensity levels, power source, and timer options.

Is there something better than a TENS unit?

People who cannot use a TENS unit may use other electrical stimulation devices. These include:

  • interferential current electrical stimulation (IFC)
  • functional electrical stimulation (FES)
  • neuromuscular electrical stimulation (NMES)

TENS units can help reduce pain in people with arthritis, sciatica, period pain, and other conditions.

They are available without a prescription.

However, people should first consult a medical professional to diagnose their pain and help them find the best TENS unit that suits their needs.