Mats, pads and coils that pulse a magnetic field into tissue. A few prescription uses exist; evidence for wellness mats is weak, and implants rule them out.
Pulsed electromagnetic field devices send pulsing current through coils to create a changing magnetic field, which induces tiny electrical currents in tissue. Consumer versions are mats, pads, belts and chair covers sold for relaxation, sleep, recovery or 'cellular energy', often combined with heat or LEDs.
The acronym covers very different things: prescription bone-growth stimulators for fractures that won't heal, cleared devices for post-operative pain and swelling, and the far stronger clinic treatment transcranial magnetic stimulation (TMS) for depression. Evidence for one says little about another. A wellness mat borrows the name, not the data.
For fractures that failed to heal, a Cochrane review of four small blinded trials found a possible benefit that wasn't statistically significant. For knee osteoarthritis, a meta-analysis of 8 sham-controlled trials found some improvement in physical function but no clear effect on pain or stiffness. There are no good trials behind the sleep, stress, 'detox' or frequency-specific claims made for consumer mats, which is telling, because PEMF is easy to test against a sham device.
Four small blinded randomized trials (125 people) of electromagnetic stimulation for long-bone fractures that hadn't healed showed a possible benefit that was not statistically significant (RR 1.96, 95% CI 0.86–4.48). The authors judged the evidence inconclusive.
In 8 placebo-controlled trials with 421 people with knee osteoarthritis, PEMF improved physical function scores but showed no significant advantage for pain or stiffness.