Frequency Specific Microcurrent: Claims, Origins, Evidence and Criticism

Frequency specific microcurrent, usually shortened to FSM (and sometimes FSMT, for "therapy"), is an alternative treatment in which a very weak electrical current is passed through the body at particular pulse frequencies. Practitioners say that each frequency targets a specific condition, such as inflammation or scarring, or a specific type of tissue, such as nerve or muscle, and that matching the right pair of frequencies to the problem helps the body heal and reduces pain.

FSM is offered by chiropractors, physical therapists, massage therapists, naturopaths and some medical doctors, and it has been promoted by at least one major American hospital system. It has also been sharply criticised by physicians and scientists who call its theory pseudoscience and point to a thin, mostly in-house research base.

This article explains what FSM is and what its practitioners claim, where its frequencies come from, how a session works, what the published studies actually show, and why critics consider its central idea implausible. It is general information, not medical advice. Anyone with pain or an injury should see a doctor or other licensed clinician for diagnosis and treatment.

The short version

What practitioners say FSM is

In its own description, FSM is the introduction of a mild electrical current into damaged soft tissue, intended to enhance the healing that is already underway. The defining features are three.

Very low current. FSM uses current measured in microamperes (µA), or millionths of an ampere. The FSM organisation's website says the current is about 1,000 times lower than that of a conventional TENS unit and below the level a person can feel, and it cites a range of 10 to 500 microamperes from research. Many patients therefore feel nothing during treatment.

Two channels with two frequencies. FSM devices have two channels. According to the FSM website, Channel A carries frequencies associated with a condition (for example, inflammation, scarring or "fibrosis"), and Channel B carries frequencies associated with a tissue type (for example, nerve, muscle, tendon or a specific organ). Frequency pairs are written in the form "40/116," with the condition frequency first and the tissue frequency second.

Specific frequency combinations. Practitioners are trained in a catalogue that the FSM website says contains more than 200 frequency combinations for pain and injury management. The idea is that a clinician assesses the patient, chooses the combinations thought to match the problem, and runs them in sequence, watching for responses such as softening of tight tissue or a drop in pain.

The current itself is delivered as a ramped square wave, according to the FSM site, through electrodes. A 2013 review co-written by McMakin describes the application methods as conductive graphite gloves worn by the practitioner, moistened towels or gel electrode patches.

The mechanism practitioners propose

FSM's explanation draws on the language of resonance. The FSM website compares the effect to a singer shattering a glass by hitting its resonant note, or to a tuning fork that makes another fork vibrate. In this account, healthy and injured tissues each have characteristic frequencies, and supplying a matching frequency changes the tissue's state.

The surgeon and writer David Gorski, quoting FSM promotional material, summarises the theory: each tissue in the body supposedly has its own frequencies, and when tissue is injured its electrons "take on a different vibrational characteristic," which the right FSM frequencies are said to "neutralise." Gorski calls this "science-y sounding gobbledygook."

The FSM website itself acknowledges that "the exact mechanisms are still being researched." It also makes strong claims, including that FSM "always works when the treatment matches the actual cause."

A more conventional-sounding set of hypotheses appears in a 2013 narrative review by McMakin and the biophysicist James Oschman in the Journal of Alternative and Complementary Medicine. That paper suggests that the tissue softening observed during FSM might reflect the resolution of elevated muscle tone left over from previous trauma or disease (drawing on Irvin Korr's "gamma loop" hypothesis), or might involve fascia, the connective tissue that wraps muscles and organs. The authors are candid that "all of these concepts are controversial," that the muscle-tone model "is not clinically proven to operate in humans," and that fascial lengthening is "probably too slow to account for the tissue softening taking place during FSM." They present several hypotheses "without favoring any one of them." Oschman disclosed honoraria and consulting fees from Frequency Specific Seminars Inc., the company that trains FSM practitioners.

The cellular energy claim

The most frequently repeated FSM claim is that microcurrent increases production of ATP (adenosine triphosphate, the molecule cells use to store and transfer energy) by up to 500%. The FSM website's description of how FSM works also claims 70% higher protein synthesis and 40% better amino acid transport, without citing a source on that page.

These figures are usually traced to a 1982 laboratory study by N. Cheng and colleagues, published in Clinical Orthopaedics and Related Research. It is worth looking at what that study actually examined. According to its abstract, the researchers applied direct current of 10 to 1,000 microamperes to samples of rat skin and found increased ATP concentrations and increased incorporation of amino acids into protein. Amino acid transport across cell membranes was stimulated between 100 and 750 microamperes. DNA metabolism was unaffected. The authors explained the ATP effect using Mitchell's chemiosmotic theory of how cells make ATP.

Three points stand out:

1. The study used rat skin tissue in a laboratory, not living human patients.
2. It used direct current, not the frequency-specific pulsed patterns that define FSM. It did not test FSM frequencies at all.
3. The abstract does not report a "500%" figure. A secondary source describing the study refers to an optimum current of about 500 microamperes, and it is possible that the "500%" claim conflates the current level with the size of the effect, though the original source of the 500% figure is not stated by those who repeat it.

Steven Novella, a neurologist who has written about FSM, characterises the ATP evidence as resting on a single in vitro study with "barely significant results," and notes that laboratory results cannot simply be extrapolated to people, especially when it is not established that such small currents penetrate the skin in a meaningful way.

Where the frequencies came from

McMakin's account

Carolyn McMakin holds a master's degree and a Doctor of Chiropractic degree. The FSM website says she developed FSM in the 1990s; the current homepage gives 1997, while an earlier version of the site, as quoted by Novella in 2019, gave 1995. She has taught FSM since at least 1998 and the organisation says it has trained more than 4,000 practitioners worldwide.

According to the FSM website as quoted by Novella, McMakin's frequencies were "passed on from an osteopath in Canada who had a practice that came with a machine made in the 1920's." The FSM site also includes a page titled "Harry Van Gelder Frequencies," associating the frequency lists with that name, though the homepage gives no further detail about him.

McMakin has described FSM's development as a process of testing which frequencies seemed to help patients. The 2010 muscle-soreness study she co-authored cites itself as a source for "the history of the discovery of effective frequencies."

The 1920s background: Albert Abrams and radionics

The detail that the frequencies came with "a machine made in the 1920's" is central to the criticism of FSM, because the 1920s was the heyday of one of the most famous medical device frauds in American history.

Albert Abrams (1863–1924) was an American physician who promoted a system he called the Electronic Reactions of Abrams, or ERA. He claimed that electrons were the fundamental element of life and that diseases had characteristic frequencies. His "dynomizer" was said to diagnose virtually any disease from a drop of blood or even a sample of handwriting. His later devices, the oscilloclast and the radioclast, were claimed to treat diseases by applying tables of frequencies designed to "attack" each illness. Operators paid for courses and leased the devices under contracts that forbade them from opening the boxes. By 1921 about 3,500 practitioners were reportedly using ERA devices.

The system collapsed under testing. The American Medical Association opposed Abrams; in one well-known test, a blood sample from a Plymouth Rock rooster was diagnosed with several human diseases. Scientific American ran an investigation in which a senior Abrams associate, identified as "Doctor X," was given six vials of unknown samples; he got every one wrong, and the magazine published its findings in 1924. Abrams himself never took part. After his death in 1924, investigators who opened his boxes found simple wiring and a motor. Novella describes the devices as "just wires and resistors that made the box hum, but didn't actually do anything else."

Abrams's ideas lived on as radionics, a field of devices that claim to diagnose and treat disease by "frequencies" or "vibrations." Gorski, citing a naturopathic source that described FSM's history, links FSM's frequencies directly to Abrams, noting that Abrams believed the frequencies involved were radio waves.

Supporters of FSM would point out that a device's ancestry does not by itself prove it ineffective; what matters is whether it works when tested. That is true, and it is why the clinical evidence, covered below, matters. But critics argue the origin is relevant because the specific numbers, the frequency for "inflammation" or for "nerve," were not derived from any measurement of tissue. If they came from a device that was itself shown to be a hoax, there is no reason to expect them to correspond to anything biological.

Where FSM fits among electrical therapies

Electrical stimulation is not inherently fringe. Several forms are mainstream, which is one reason FSM can sound plausible to patients. It helps to see where FSM sits.

What distinguishes FSM from mainstream electrical therapy is not the electricity but the claim of frequency specificity: that one number treats inflammation and another treats scar tissue, and that a particular pair targets a particular tissue. That claim has no basis in established physiology and has not been independently demonstrated.

How a session works

The details below describe how practitioners say FSM is delivered. They are not a recommendation.

1. Assessment. The practitioner takes a history; the FSM website puts heavy weight on history-taking and says that 85% of diagnosis comes from it. The practitioner decides which conditions and tissues are thought to be involved.
2. Electrode placement. Electrodes, graphite gloves or wet towels are placed so that the current passes through the area of complaint.
3. Frequency selection. The practitioner runs a series of frequency pairs on the device's two channels. For some problems the protocol involves testing several combinations in turn. The 2013 review describes testing "eight possible frequency combinations" in sequence for sinus conditions until one produces softening.
4. Response. Patients typically feel little or nothing from the current itself. Practitioners look for reported pain relief or palpable softening of tissue.

The 2010 muscle-soreness study used 20 minutes of treatment, and the 2025 scleroderma pilots used sessions of 45 and 60 minutes. Practitioners may also sell or recommend home units.

Training and the professional network

FSM is taught by Frequency Specific Seminars. Its website says that to get started, a practitioner must register for "CORE TRAINING," available as a 5-day in-person seminar or a 40-hour online core course priced at $1,695, followed by practicums and advanced seminars, with specialised tracks such as FSM Rehab and FSM Dental and a twice-yearly symposium. Upcoming core courses listed in late 2026 included one in London and one in Troutdale, Oregon. Practitioner directory listings are described as people who have completed courses, testing and certification. The homepage also includes the statement "While we make no medical claims."

Practitioners' own safety warnings

FSM's current is very weak, but the FSM organisation publishes a list of contraindications and precautions. The fact that its own materials warn about some frequency combinations causing unwanted effects is notable, since it implies a strong belief in specific frequency effects. The published list includes:

• Pregnancy: "FSM should not be used during pregnancy," because the effect on the developing fetal nervous system is unknown.
• Pacemakers: caution, treating only above the collarbone and below the waist, with monitoring; extra caution or no treatment for patients who are fully pacemaker-dependent.
• Active cancer: "DO NOT treat cancer with FSM," though the materials say FSM may be used for radiation burns, scarring and chemotherapy side effects.
• Diabetes: do not treat the pancreas in insulin-dependent patients, citing a risk of dangerous low blood sugar.
• Implanted pumps: turn off or do not treat, especially insulin pumps.
• Cardiac monitors: the current interferes with them.
• Acute infections: do not use over areas of active infection, with specific frequencies to avoid.
• Recent injury or surgery: certain frequencies are not to be used within set periods after injury.
• Specific combinations: several frequency pairs are listed as "do not use," and others with time limits.

Some of these, such as care around pacemakers and implanted pumps, reflect general cautions that apply to any electrical stimulation near implanted devices. Others depend on FSM's frequency theory.

From a medical perspective, the more important risk is indirect. A treatment with little proven benefit can cause harm if it delays diagnosis or effective care, for example if pain from a fracture, infection, nerve compression or tumour is treated with microcurrent instead of being investigated. In 1994 the American Cancer Society reviewed electronic devices promoted as cancer treatments, found no evidence of objective benefit and "strongly urge[d] individuals with cancer not to seek treatment with such devices." That review did not examine FSM specifically, and FSM's own guidance says not to treat cancer with it, but it illustrates the long history of electronic "frequency" devices being marketed for serious disease.

What the published evidence shows

How much research exists

A PubMed search for "frequency specific microcurrent" in October 2026 returned 19 results. Several of these are unrelated to FSM (for example, physics papers and studies of other microcurrent applications that happen to match the search terms). The FSM-specific clinical literature is small. Here are the main studies.

The 2010 muscle-soreness trial

The most-cited FSM trial is Curtis, Fallows, Morris and McMakin (2010) in the Journal of Bodywork and Movement Therapies. Thirty-five healthy adults (18 men and 17 women, mean age 32) did a treadmill warm-up and eccentric leg-curl exercise to induce delayed onset muscle soreness (DOMS), the aching that follows unaccustomed exercise. One leg then received 20 minutes of FSM, and the other leg was left untreated as a control. Soreness was rated on a 0–10 scale.

The authors reported p = 0.0005 at each follow-up and concluded that FSM provided "significant protection from DOMS at all time points tested."

On paper, those are very large effects. Critics point to several problems:

• Comparison against an untreated leg. The abstract refers to a sham comparison in its framing, but the described design compared a treated leg with an untreated one. Because FSM is sub-sensory, a sham is easy to arrange, so not using one is a significant weakness.
• Blinding not described. Novella noted that the paper did not report blinding. Participants knew which leg had been treated, and soreness is a subjective rating highly susceptible to expectation.
• Identical p-values. Novella pointed out that the three follow-up comparisons all reported exactly p = 0.0005, which he described as suspiciously uniform.
• Involvement of the developer. McMakin was a co-author.
• No independent replication of this result has been published.

A worked example shows why blinding matters so much here. Hypothetical illustration: imagine that the true effect of FSM on soreness is zero, but that knowing which leg was treated makes participants rate it 2 points lower out of 10 simply because they expect it to feel better. A study like this would then report a 2-point "benefit" that is entirely expectation. Without blinding and a sham, the study cannot distinguish a real effect from an expectation effect of this kind.

The 2012 Achilles tendinopathy review

A 2012 systematic review and meta-analysis of physical therapies for Achilles tendinopathy by Sussmilch-Leitch and colleagues, in the Journal of Foot and Ankle Research, found limited evidence, based on a single randomised clinical trial, that microcurrent may be effective. Evidence based on one trial is, by the standards of systematic reviews, weak; it indicates that more research is needed rather than that a treatment works.

The 2013 McMakin and Oschman review

As described above, this paper presented hypotheses about why tissue seems to soften during FSM but contained no new data. The authors cite earlier "multicenter clinical case reports" and acknowledge that the concepts they discuss are controversial.

The 2020 neck and low back pain study

Shetty and colleagues (2020), also in the Journal of Bodywork and Movement Therapies, conducted a retrospective case-control study, meaning they looked back at existing patient records rather than running a planned trial. They compared 213 patients who had received FSM alongside physical rehabilitation (167 with low back pain, 46 with neck pain) with 78 controls who had rehabilitation alone (61 low back, 17 neck).

• Low back pain: The FSM group had lower average pain after treatment (p = 0.02) and higher proportions reaching a pain score of 3 or below, minimal disability and "full success."
• Neck pain: No significant differences in pain, disability or outcome.

The authors suggested FSM could be a useful addition to low back pain rehabilitation. Retrospective comparisons, however, cannot rule out differences between the groups, such as who was offered FSM and why, and they are not blinded. Interestingly, the result was positive for one condition and null for the other, which is the kind of mixed pattern that calls for a properly randomised trial.

A quick worked calculation shows how unequal the groups were: 213 FSM patients against 78 controls is a ratio of about 2.7 to 1, and for neck pain there were only 17 controls. With samples that small, a real difference can easily be missed and a spurious one can easily appear.

The 2025 scleroderma pilot studies

Gregory and colleagues (2025), in Rheumatology, reported two small pilot studies in a total of 17 patients with systemic sclerosis (scleroderma), a disease that causes skin thickening and often Raynaud's phenomenon (painful colour changes in fingers in the cold). Patients received FSM targeting scarring in the hands and capillaries, and Raynaud's, in sessions of 60 minutes in one study and 45 minutes in the other, over one or two days.

Hand function, measured with the Cochin hand function score, improved by an average of 40% across both studies (95% confidence interval 26% to 55%), and Raynaud's severity on a 100-point visual analogue scale improved by an average of 18 points. The authors themselves stated that "further randomized, controlled studies are needed to confirm these results," and that longer follow-up is needed to see whether any benefit lasts. Without a control group, the results cannot separate any effect of FSM from placebo effects, natural fluctuation, regression to the mean or the effect of extra attention from clinicians.

Case reports and other small studies

The remaining FSM-specific literature consists largely of case reports and pilots: for example, a 2019 report on three wounded military service members (Sharp, Medical Acupuncture), a 2019 case report on congenital muscular torticollis in a child (Thompson, Pediatric Physical Therapy), and a 2025 pilot randomised trial of FSM and relaxation in adults with distress (Pereira, Healthcare). Case reports can suggest ideas worth testing but cannot establish that a treatment works, because they lack comparison groups.

Putting it together

This is the profile of a treatment that has not been shown to work. It is not proof that FSM does nothing. It means that the claims made for it run far ahead of the evidence.

The critics' case

"Vibrational" medicine and physics

Critics' first objection is to the mechanism. Novella and other skeptics classify FSM as a form of "vibration medicine" or energy medicine and argue there is no good evidence that injured tissue takes on a "different vibrational characteristic." Gorski argues that changing the behaviour of electrons in tissue in the way FSM's promotional language describes would require energy, and that the proposed mechanism reflects a poor grasp of basic physics.

The resonance analogy also does not fit well. A wine glass shatters at its resonant frequency because it is a rigid object with a sharply defined natural vibration, and the singer supplies a great deal of acoustic energy at exactly that frequency. Living tissue is wet, soft, heavily damped and constantly changing; it does not have a single sharp "note," and a sub-sensory current carries very little energy. Saying that tissues "resonate" with FSM frequencies describes a metaphor, not a measured phenomenon.

The origin of the numbers

The second objection is about where the frequencies come from. If the frequency for, say, "inflammation" was not derived from any measurement of inflamed tissue, and instead came from a list associated with a 1920s device in the radionics tradition, then the specificity claim has no foundation. Novella concludes that FSM's claims "are rooted in demonstrable fraud (Abrams)."

The research base

The third objection concerns who has done the research. Novella observed in 2019 that the Cleveland Clinic's FSM page cited five references, all by McMakin, and called FSM "the vanity project, apparently, of one chiropractor, not a serious avenue of medical research." Studies by the developer of a treatment are not automatically wrong, but independent replication is the standard way science guards against the biases that affect all researchers who believe in their own methods.

Institutional promotion

Critics have also objected to mainstream institutions offering FSM. In 2015 Gorski criticised the Cleveland Clinic Children's Center for Pediatric Integrative Medicine, led by Dr Benjamin Katholi, for planning research on acupuncture, reiki and FSM, and for offering a list of services that included reiki and therapeutic touch alongside FSM. In 2019 Novella noted that the Cleveland Clinic was promoting FSM for 22 conditions, which he described as a list that looked designed for marketing, and wrote that the clinic "should be ashamed of promoting such rank pseudoscience." The Wikipedia article on FSM summarises the critics' position that the mechanism is implausible and the research base does not establish either the phenomenon or the clinical claims.

Regulation

FSM devices are electrical stimulators. The FSM organisation says its devices are cleared by the U.S. Food and Drug Administration in the TENS category for pain management, and its own materials state that the specific frequency applications have not been evaluated by the FDA. It is important to understand what that distinction means. A clearance for a device category, such as a TENS-type stimulator for pain, covers that general use. It does not mean the FDA has evaluated or endorsed the claim that particular frequency pairs treat particular conditions or tissues. The FSM website's own description notes this gap.

Patients sometimes encounter the phrase "FDA-approved" in connection with FSM. Clearance of a device in a category is not an endorsement of every claim made by people who use it.

Why people report that it helps

Many patients and practitioners sincerely report that FSM relieves pain. There are several well-documented reasons why a treatment with no specific effect can still feel effective:

• Placebo and expectation. Pain is strongly influenced by expectation, attention and context. A calm, attentive clinician, a credible-looking device and a confident explanation can all reduce reported pain.
• Natural history. Many painful conditions, including muscle soreness and many back-pain episodes, improve on their own over days or weeks. Treatments given during that period get the credit.
• Regression to the mean. People tend to seek treatment when symptoms are at their worst. On average, symptoms then become less severe, whatever is done.
• Combined treatment. FSM is often delivered alongside massage, manual therapy, exercise or rehabilitation, which may account for improvements.
• Subjective outcomes. Most FSM outcomes are pain and function ratings, which are important to patients but especially susceptible to the effects above unless studies are blinded.

These factors are exactly why controlled, blinded trials exist. They are not a criticism of patients; they affect everyone.

Understanding the units

Because FSM's marketing leans on the idea of tiny currents, it helps to be clear about what the numbers mean.

An ampere (A) is the basic unit of electric current. A milliampere (mA) is one thousandth of an ampere, and a microampere (µA) is one millionth. So:

• 1 mA = 1,000 µA
• 100 µA = 0.1 mA = 0.0001 A
• 500 µA = 0.5 mA = 0.0005 A

Worked example: the FSM website cites a range of 10 to 500 microamperes. Converting, that is 0.01 to 0.5 milliamperes. If, as the FSM site says, FSM current is roughly 1,000 times lower than a typical TENS unit, then a TENS current a thousand times larger than 10 µA would be 10 mA. These figures are given only to show how the units relate, not as specifications for any particular device.

The low current is presented as a selling point, because it means the treatment is not felt. But it also cuts the other way. A current too weak to stimulate the nerves that produce sensation is also too weak to have the familiar effects of TENS, which works partly by producing a tingling sensation that interferes with pain signalling. For FSM to do something, its effects would have to come through a different, as yet undemonstrated route, which is exactly what its frequency theory proposes and what critics doubt.

How to judge a claim like this

FSM is a useful case study in evaluating any health product that comes with a technical-sounding explanation. A few questions help.

Is the mechanism consistent with what is already known? A new treatment does not need a fully understood mechanism to work; many medicines were used before anyone knew how they acted. But a mechanism that contradicts established physics or physiology raises the bar for evidence. FSM's claim that specific frequencies correct specific "vibrational" states in specific tissues has no grounding in measured properties of tissue.

Where did the key numbers come from? For a genuine therapy, doses and settings are derived from experiments. FSM's frequencies, by its developer's account, came with an old machine.

Who did the studies? Research by a treatment's inventor or by people paid by the company that sells training is not automatically wrong, but it needs independent confirmation. Most FSM studies involve McMakin or people connected to FSM training.

Were the studies blinded and controlled? For subjective outcomes such as pain, unblinded studies without a sham comparison are especially likely to show benefit whether or not the treatment works.

How many conditions is it claimed to treat? Treatments that are said to help a very wide range of unrelated conditions, as FSM is in some promotional materials, are usually treating something common to all of them, such as expectation and attention, rather than each disease specifically.

What happens if you skip it? The opportunity cost matters. Time and money spent on an unproven therapy may be time and money not spent on diagnosis and treatment with proven value.

Questions a patient might ask

If someone is offered FSM, reasonable questions to put to the practitioner include: What is the diagnosis, and has it been confirmed by a doctor? What independent, controlled trials support this treatment for this specific condition? How many sessions are proposed, and at what total cost? What would be the alternative, evidence-based treatment, and why is this preferred? And what outcome would show that it is not working, so that a different approach can be tried?

Common misconceptions

"It's electrical, so it must be scientific." Electricity is used in many proven treatments, but FSM's distinctive claim is about specific frequencies, and that claim has not been demonstrated.

"It's FDA-approved for all these conditions." According to the FSM organisation's own materials, devices are cleared in the TENS category for pain, and the frequency applications have not been evaluated by the FDA.

"Research shows a 500% increase in ATP." The study usually cited for this used direct current on rat skin in a laboratory, did not test FSM frequencies, and its abstract does not report a 500% figure.

"A major hospital offers it, so it must be proven." Hospitals sometimes offer complementary or integrative therapies for patient demand. Critics have specifically objected to the Cleveland Clinic's promotion of FSM, and the presence of a therapy on a hospital website is not evidence.

"If it doesn't work, the studies would show that." The existing studies are mostly too small, too poorly controlled or too closely tied to the developer to show either way. Absence of good negative trials is not evidence of benefit.

"It can't hurt to try." The current is low, but treatment costs money and time, and the bigger risk is delaying proper diagnosis of a condition that needs medical care.

Frequently asked questions

Who invented FSM? Carolyn McMakin, a chiropractor with an MA and a DC, in the mid-1990s. The FSM website gives 1997 on its current homepage; an earlier version cited by Novella said 1995.

How strong is the current? In the microampere range. The FSM website cites 10 to 500 microamperes and says this is about 1,000 times less than a typical TENS unit and below the level of sensation.

What do the two numbers in a frequency pair mean? In FSM practice the first number (Channel A) is said to represent a condition such as inflammation, and the second (Channel B) a tissue type such as nerve or muscle.

Is there good evidence that FSM works? Not by the usual standards of medicine. The evidence consists of a small number of small or uncontrolled studies, several co-authored by the developer, with no large, independent, blinded and sham-controlled trials.

What is the connection to Albert Abrams? McMakin has said the frequencies came from a Canadian osteopath's practice that included a 1920s machine. Critics, including Gorski and Novella, link these frequencies to the tradition of Abrams, a 1920s physician whose "frequency" devices were exposed as worthless.

Is FSM safe? The current is very low. The FSM organisation lists contraindications including pregnancy, pacemakers, insulin pumps, active cancer and infections. The main risk identified by critics is using FSM instead of effective, evidence-based care. Anyone considering it should speak to a doctor first.

Why do so many people feel better after FSM? Placebo effects, natural recovery, regression to the mean and co-treatments such as massage or exercise can all produce improvement. Only well-designed trials can tell whether FSM adds anything beyond these.

What would change the scientific view? Large randomised trials, run by independent researchers, with a sham device indistinguishable from the real one, blinded participants and assessors, outcomes fixed in advance, and replication across different centres. If FSM produced consistent benefits under those conditions, the evidence would need to be taken seriously regardless of its origins.

The bottom line

FSM combines something genuinely established, the fact that electrical stimulation can affect nerves and muscles, with something that is not, the idea that specific frequencies correct specific "vibrational" problems in specific tissues. Its frequency lists trace back, by its developer's own account, to a 1920s machine, an era and tradition marked by discredited frequency devices. The research supporting it is small, often uncontrolled and largely connected to the developer. Patients may feel better after treatment, but that is true of many treatments that turn out to have no specific effect. For pain or injury, the sensible first step is a proper diagnosis from a doctor and treatments with established evidence.

Sources

• Frequency specific microcurrent (Wikipedia)
• Novella, "Frequency Specific Microcurrent," Science-Based Medicine (2019)
• Gorski, "Quackademic medicine tightens its hold on the Cleveland Clinic" (2015)
• McMakin & Oschman (2013), "Visceral and Somatic Disorders: Tissue Softening with Frequency-Specific Microcurrent," J Altern Complement Med
• Curtis et al. (2010), "The efficacy of frequency specific microcurrent therapy on delayed onset muscle soreness," J Bodyw Mov Ther
• Sussmilch-Leitch et al. (2012), "Physical therapies for Achilles tendinopathy: systematic review and meta-analysis," J Foot Ankle Res
• Cheng et al. (1982), "The effects of electric currents on ATP generation, protein synthesis, and membrane transport of rat skin," Clin Orthop Relat Res
• PubMed search results for "frequency specific microcurrent"
• "Questionable methods of cancer management: electronic devices," CA Cancer J Clin (1994)
• Albert Abrams (Wikipedia)
• Frequency Specific Seminars (official site)
• FSM: How Frequency Specific Microcurrent Works (official site)
• FSM: Contraindications and Precautions (official site)