From the Guidelines
Transcutaneous Electrical Nerve Stimulation (TENS) units are recommended for pain management, with a usage duration of 20-30 minutes per session, up to several times daily as needed, starting with low-intensity settings (below 10 mA) and gradually increasing to a comfortable level (usually 10-30 mA) 1.
Usage and Dosage
The frequency settings for TENS units generally range from 80-120 Hz for acute pain and 2-10 Hz for chronic pain, with pulse widths between 50-200 microseconds 1.
- Electrode pads should be placed either directly over the painful area, surrounding the painful region, along the nerve pathway that supplies the painful area, or at specific acupuncture points.
- TENS works by stimulating sensory nerves to block pain signals (gate control theory) and by triggering the release of endorphins, the body's natural painkillers.
Precautions and Considerations
Before using a TENS unit, patients should consult healthcare providers, especially those with pacemakers, heart conditions, epilepsy, or during pregnancy 1.
- The skin should be clean and free of oils before applying electrode pads, and pads should be regularly replaced when adhesion diminishes.
- TENS provides a non-pharmacological pain management option with minimal side effects and no risk of dependency, as supported by moderate-certainty evidence showing that TENS reduced pain at less than 2 hours compared with placebo (WMD, −1.94 cm [CI, −2.90 to −0.98 cm]) 1.
From the Research
Recommended Usage and Dosage for TENS Units
The recommended usage and dosage for Transcutaneous Electrical Nerve Stimulation (TENS) units for pain management vary depending on the individual and the type of pain being treated.
- TENS units can be used to treat both acute and chronic pain conditions, including procedural pain, postpartum uterine contractions, and rib fractures 2.
- The optimal dosage of TENS has not been established, but studies suggest that high-frequency TENS (HF-TENS) and low-frequency TENS (LF-TENS) can provide analgesia when applied at a strong, non-painful intensity 3.
- The intensity of the stimulation is critical to therapeutic success, and the dosage should be individualized based on the patient's response to treatment 4.
Safety and Adverse Effects
- TENS is generally considered safe, with minor adverse effects such as mild erythema and itching underneath the electrodes reported in some studies 2.
- The risk of bias associated with inadequate sample sizes in treatment arms and unsuccessful blinding of treatment interventions is high, making definitive conclusions about the efficacy of TENS difficult to draw 2, 5.
Clinical Evidence
- A Cochrane Review of 19 randomized controlled trials (RCTs) found tentative evidence that TENS reduces pain intensity over and above that seen with placebo TENS when administered as a stand-alone treatment for acute pain in adults 2.
- Another Cochrane Review of 51 TENS-related RCTs found that the evidence for the effectiveness of TENS in reducing pain in adults with chronic pain is very low quality due to significant methodological limitations and imprecision 5.
- A literature review published in 2022 concluded that TENS may have efficacy for a variety of acute and chronic pain conditions, although the magnitude of the effect remains uncertain due to the low quality of existing literature 4.