Electrotherapy is the use of electrical energy as a medical treatment. In medicine, the term electrotherapy can apply to a variety of treatments, including the use of electrical devices such as deep brain stimulators for neurological disease. Electrotherapy is a part of neurotherapy aimed at changing the neuronal activity. The term has also been applied specifically to the use of electric current to speed up wound healing. The use of electromagnetic stimulation or EMS is also very wide for dealing with muscular pain. Additionally, the term "electrotherapy" or "electromagnetic therapy" has also been applied to a range of alternative medical devices and treatments. Evidence supporting the effectiveness of electrotherapy is limited (see section Medical uses below).

Electrotherapy is primarily used in physical therapy for:

There is limited evidence supporting electrotherapy, specifically in treating musculoskeletal, osteoarthritis, fibromyalgia, neck pain, lumbopelvic pain, and ulcer conditions. Some of the treatment effectiveness mechanisms are little understood. The natural neurostimulation hypothesis explains the therapeutic effect by the fact that energy stimuli induce mitochondrial stress and microvascular vasodilation. Since healthy neurostimulation should emulate the physical characteristics of a mother's care for her fetus during pregnancy scaled to the treatment parameters of the specific patient, but many techniques of electrotherapy do not consider this, the hypothesis claims that their effectiveness and some practices for their use still anecdotal.

In general, there is little evidence that electrotherapy is effective in the management of musculoskeletal conditions. In particular, there is no evidence that electrotherapy is effective in the relief of pain arising from osteoarthritis, and little to no evidence available to support electrotherapy for the management of fibromyalgia.

A 2016 review found that, "in evidence of no effectiveness," clinicians should not offer electrotherapy for the treatment of neck pain or associated disorders. Earlier reviews found that no conclusions could be drawn about the effectiveness of electrotherapy for neck pain, and that electrotherapy has limited effect on neck pain as measured by clinical results. A later 2023 review confirmed this conclusion that there is limited high-quality evidence for the use of electromagnetic stimulation for pain relief.

A 2015 review found that the evidence for electrotherapy in pregnancy-related lower back pain is "very limited".

A 2014 Cochrane review found insufficient evidence to determine whether electrotherapy was better than exercise at treating adhesive capsulitis. As of 2004, there is insufficient evidence to draw conclusions about any intervention for rotator cuff pathology, including electrotherapy; furthermore, methodological problems precluded drawing conclusions about the efficacy of any rehabilitation method for impingement syndrome.

There is limited, low quality evidence for a slight benefit of noxious-level electrotherapy in the treatment of epicondylitis.