Is TMS Safe? What the Evidence Says About Side Effects
TL;DR
This guide summarizes what the published clinical literature, led by a 2025 consensus review (Trapp et al., 2025), reports about TMS safety. It covers the most commonly reported side effects, seizure risk, what is and isn't known about long-term safety, who needs additional screening before treatment, and how TMS side effects differ from those of antidepressant medication. Whether TMS is appropriate for you depends on an individual evaluation with a qualified clinician.
Table of Contents
- What the evidence shows
- TMS side effects
- Can TMS cause a seizure?
- Do TMS side effects get better over time?
- Long-term safety
- TMS contraindications and screening
- Why do some people report bad experiences online?
- How do TMS side effects compare to antidepressant medication?
TMS (transcranial magnetic stimulation) has held FDA clearance for depression since 2008. It is non-invasive: no anesthesia, no incision, and no drug entering the bloodstream.
TMS for depression carries a generally favorable safety and tolerability profile, a conclusion reached in a 2025 consensus review jointly endorsed by the National Network of Depression Centers, the Clinical TMS Society, and the International Federation of Clinical Neurophysiology (Trapp et al., 2025).
Seizure is the most serious known side effect, but it is rare. With standard figure-8 coil protocols the reported incidence is about 1 in 12,500 treatments (0.008%). Reported TMS seizures have been self-limited, and none have led to an ongoing seizure disorder (Trapp et al., 2025).
More than 20 million figure-8 coil treatments have been delivered since 2008 without any identified pattern of long-term side effects, though the long-term safety of repeated stimulation over extended periods is still being characterized (Trapp et al., 2025).
Patients with ferromagnetic metal or electronic implants near the coil, or with seizure risk factors, need clinician screening before treatment (Rossi et al., 2021; Trapp et al., 2025).
Is TMS safe? What the evidence actually shows
The most authoritative answer comes not from any single clinic or device maker but from a 2025 consensus review published in Clinical Neurophysiology and endorsed by three major professional bodies: the National Network of Depression Centers, the Clinical TMS Society, and the International Federation of Clinical Neurophysiology. Its conclusion is direct: repetitive TMS for major depression "has a generally favorable safety and tolerability profile" (Trapp et al., 2025). That verdict draws on the accumulated clinical and trial literature rather than marketing claims, which is why it carries weight.
Part of why TMS avoids the risks patients associate with other depression treatments comes from how it works. A coil placed against the scalp delivers focused magnetic pulses that stimulate neurons in a targeted region of the brain. The procedure requires no anesthesia, no incision, and no drug entering the bloodstream. Because nothing circulates through the body, TMS avoids the body-wide side effects associated with oral medication, such as weight change and sexual dysfunction, and the pulses act on the tissue beneath the coil rather than throughout the body.
The safety record also rests on scale and time. High-frequency TMS with the figure-8 coil has been FDA-cleared since 2008, and more than 20 million treatments with that coil have been delivered to date without any identified pattern of long-term side effects (Trapp et al., 2025). That combination of a favorable trial profile and nearly two decades of real-world use is why clinicians describe TMS safety with confidence.
TMS side effects: what to expect
The most common side effects are mild, occur during or shortly after a session, and are time-limited. The consensus review reports the following incidence figures for repetitive TMS in depression (Trapp et al., 2025):
Every one of these effects is described in the consensus review as acute and time-limited (Trapp et al., 2025). The discomfort most patients feel traces back to a single mechanical fact: the magnetic pulse contracts scalp and facial muscles near the coil, and that muscle activity produces the pain and the tension-type headache. Both occur during the procedure and settle afterward.
A short list of very rare effects with incidence likely well below 0.1%, hard to quantify, and with an unclear causal link to TMS, includes syncope (fainting), posterior vitreous detachment, retinal tear, and tinnitus (Trapp et al., 2025). A hearing-related risk also exists from the acoustic click of each pulse, which is why both patient and operator should wear ear protection providing at least 30 dB of noise reduction during treatment (Trapp et al., 2025).
Can TMS cause a seizure?
Seizure is the most serious known side effect of TMS, and it is rare. Across standard clinical protocols the reported incidence is less than 0.1%, and it varies by coil design. For figure-8 coils the reported rate is roughly 1 in 12,500 treatments (0.008%). Some studies place the risk as low as 1 in 33,000 (0.003%). Deeper-stimulating H1 coils, delivered at higher frequency, carry a somewhat higher reported rate of roughly 1 in 2,000 (Trapp et al., 2025).
Just as important as the frequency is the pattern. Seizures reported with TMS to date have been self-limited, occurred at the time of stimulation, and have not resulted in an ongoing seizure disorder (Trapp et al., 2025). Seizures in the setting of TMS are generally considered provoked, which means the risk of recurrent seizures is minimal in the absence of that provocation (Rossi et al., 2021). To put the magnitude in context, the incidence with TMS is lower than that of a seizure-threshold-lowering antidepressant such as bupropion (0.35–0.44%) (Trapp et al., 2025).
The risk is dependent on stimulation intensity, which is why accurate motor-threshold determination and proper screening are the levers that keep it low. Standard high-frequency courses are dosed no more than 120% of the motor threshold, and the consensus recommends checking the motor threshold at baseline with weekly rechecks or rechecks whenever something may have changed a patient's cortical excitability (Trapp et al., 2025). One practical note for clinicians and patients alike: vasovagal syncope (fainting) can also occur with TMS, especially early in a course, and because true seizures are so infrequent, a vasovagal episode should be high on the list of explanations to be considered for any loss of consciousness during treatment (Trapp et al., 2025).
Do TMS side effects get better over time?
For most patients, yes. The common effects, including scalp discomfort and tension-type headache, are described in the consensus literature as acute and time-limited, meaning they are tied to the session rather than accumulating over a course (Trapp et al., 2025).
Clinicians can also actively ease the stimulation intensity of the early sessions. A common technique is a "ramp-up," in which stimulation starts at a lower amplitude and gradually increases over the first trains or days to let the patient acclimate to the sensation. Patients who develop headaches can usually manage them with over-the-counter pain relief recommended by their clinician (Trapp et al., 2025).
Long-term safety: what happens over months and years
The strongest evidence here is the combination of scale and surveillance. High-frequency TMS has been FDA-cleared since 2008, and more than 20 million figure-8 coil treatments have been delivered without any identified pattern of long-term side effects (Trapp et al., 2025). Studies to date have detected no acute adverse effects on cognition or neurologic status (Trapp et al., 2025).
The consensus review states plainly that while no acute cognitive or neurologic harm has been detected, "the long-term safety of delivering TMS treatment repeatedly over extended periods of time remains largely unknown" (Trapp et al., 2025). Peer-reviewed cognitive follow-ups and structural imaging studies extending well beyond a treatment course are still limited. Nothing in the existing evidence points to a mechanism of cumulative injury but the absence of a detected harm signal is not the same as long-horizon proof, and any patient weighing TMS should treat that gap as open rather than closed.
Overall, TMS has a strong safety record, and the remaining uncertainty sits in long-term cognitive and imaging data, not in any harm signal the current evidence has actually detected.
Who should not get TMS: contraindications and screening
Any ferromagnetic material within 10 cm of the coil is typically considered to rule out treatment, because of the potential for the magnetic field to heat, move, or damage it. This 10 cm threshold reflects updated safety data; device makers had originally recommended a 40 cm minimum distance (Rossi et al., 2021; Trapp et al., 2025).
The concern is physical, not merely procedural. The field can sometimes exert force on ferromagnetic objects and can induce heating in conductive implants.
Distance is decisive for programmable electronic devices: stimulation within 10 cm can cause temporary malfunction, and within 2 cm can cause permanent malfunction (Trapp et al., 2025). Devices such as deep brain stimulators, vagus nerve stimulators, cochlear implants, intracranial stents, and intracranial electrodes have not been definitively established as safe under TMS, so each case must be assessed individually. TMS should be avoided in patients with cochlear implants unless a specific safety evaluation shows no adverse effects (Rossi et al., 2021). Much modern hardware is now non-ferromagnetic (for example, titanium) and MRI-compatible, but that should be confirmed for each individual patient (Trapp et al., 2025).
Seizure risk factors call for review rather than automatic exclusion. The pre-TMS evaluation focuses on identifying: a personal or family history of epilepsy or seizure; a past stroke or head injury with neurologic consequences; concurrent use of medications or substances that alter the seizure threshold (such as anticonvulsants, amphetamines, or benzodiazepines); and medical or neurologic conditions that can lower the threshold, including sleep deprivation, increased intracranial pressure, electrolyte imbalance, and substance use or withdrawal (Trapp et al., 2025). Heavy alcohol or recreational drug use during treatment, and a diagnosis of epilepsy, are better treated as relative contraindications that require a case-by-case risk–benefit discussion between the clinical team and the patient (Trapp et al., 2025).
In practice, an initial evaluation reviews the patient's medical, surgical, neurologic, and psychiatric history along with current and prior medications, paired with a focused physical exam scaled to the individual's risk factors. The prescribing clinician holds ultimate responsibility for the safety of the procedure (Trapp et al., 2025). That screening step is where a candidate confirms TMS is appropriate for their specific history.
Why do some people report bad experiences online?
Searches for phrases like "TMS ruined my life" turn up accounts describing lasting harm, and those experiences deserve a serious explanation rather than dismissal. The pattern they describe is not reflected in the controlled clinical literature summarized by the consensus review, which draws on trials specifically designed to detect and report adverse events (Trapp et al., 2025).
None of this means individual patients are wrong about what they felt; their symptoms are real. The point is narrower: the controlled evidence does not show TMS causing those symptoms at a detectable rate, which is a different claim than saying the experiences did not happen.
How do TMS side effects compare to antidepressant medication?
The two treatments produce fundamentally different kinds of side effects because they act in fundamentally different ways. An oral antidepressant circulates through the bloodstream and reaches every organ system, which is why its side effects can include weight change, sexual dysfunction, digestive symptoms, and cardiac effects. TMS acts locally at the treatment site and does not circulate, so its documented effects are scalp discomfort and headache rather than systemic ones (Trapp et al., 2025).
On the specific question of seizure risk, the comparison is quantified: TMS seizure incidence is lower than that of bupropion, a commonly prescribed antidepressant that lowers the seizure threshold (0.35–0.44%) (Trapp et al., 2025).
In terms of overall tolerability, the proportion of patients who decide to stop treatment early is typically several times higher for antidepressant medications than for TMS. In one large meta-analysis of 117 trials of antidepressant medication, 6 297 out of 25 106 patients receiving an active treatment (25.1%) stopped taking the medication before completing the initial 8 weeks of treatment (Cipriani et al., 2009). For comparison, the all-causes discontinuation rate for TMS in large clinical trials is typically around 4-8% (Blumberger et al., 2018; 2022).
Frequently asked questions
Is TMS safe? TMS holds FDA clearance for depression and carries a generally favorable safety and tolerability profile according to a 2025 consensus review endorsed by the National Network of Depression Centers, the Clinical TMS Society, and the International Federation of Clinical Neurophysiology. Serious side effects are rare, the most serious being seizure, and the common side effects are mild and time-limited (Trapp et al., 2025).
What are the most common TMS side effects? The most common are scalp or stimulation-site pain and discomfort (about 39%) and tension-type headache (28–65%). Less frequent effects include nausea (7–11%), dizziness (4–9%), fatigue (7–8%), and insomnia (5–7%). All are acute and typically ease over the course of treatment (Trapp et al., 2025).
Can TMS cause a seizure? It can, but the risk is rare — about 1 in 12,500 treatments (0.008%) with standard figure-8 coil protocols, and as low as 1 in 33,000 in some studies. Reported TMS seizures have been self-limited, occurred at the time of stimulation, and have not led to an ongoing seizure disorder. Proper screening and motor-threshold-based dosing keep the risk low (Trapp et al., 2025).
Are there long-term risks from TMS? More than 20 million figure-8 coil treatments have been delivered since 2008 without any identified pattern of long-term side effects, and no acute cognitive or neurologic harm has been detected. That said, the long-term safety of repeated stimulation over extended periods is still being characterized, so patients should discuss individual risk factors with a clinician (Trapp et al., 2025).
Who should not get TMS? The one absolute contraindication in clinical guidelines is the presence of ferromagnetic material within 10 cm of the coil such as certain implanted pulse generators, cochlear implants, or aneurysm clips — because the field could potentially heat, move, or damage it. Seizure history, pregnancy, certain medications, and implanted electronic devices call for clinician review rather than automatic exclusion (Rossi et al., 2021; Trapp et al., 2025).
How do TMS side effects compare to antidepressant medication? TMS produces localized effects at the treatment site rather than the systemic effects common with antidepressants, such as weight gain or sexual dysfunction. Its seizure risk is also lower than that of bupropion. The overall percentage of people who decide to stop TMS is also several times lower than for antidepressant medications. However, the right choice depends on your history and the specific medication being considered (Trapp et al., 2025).
If you're considering TMS, the next step is a screening with a qualified provider. Find a TMS provider near you.
References:
Trapp NT, et al. Consensus review and considerations on TMS to treat depression: A comprehensive update endorsed by the National Network of Depression Centers, the Clinical TMS Society, and the International Federation of Clinical Neurophysiology. Clinical Neurophysiology, 2025;170:206–233. Rossi S, et al. Safety and recommendations for TMS use in healthy subjects and patient populations, with updates on training, ethical and regulatory issues: Expert Guidelines. Clinical Neurophysiology, 2021;132:269–306.
Cipriani A, Furukawa TA, Salanti G, Geddes JR, Higgins JP, Churchill R, et al. Comparative efficacy and acceptability of 12 new-generation antidepressants: a multiple-treatments meta-analysis. Lancet. 2009;373(9665):746-58.
Blumberger DM, Vila-Rodriguez F, Thorpe KE, Feffer K, Noda Y, Giacobbe P, Knyahnytska Y, Kennedy SH, Lam RW, Daskalakis ZJ, Downar J. Effectiveness of theta burst versus high-frequency repetitive transcranial magnetic stimulation in patients with depression (THREE-D): a randomised non-inferiority trial. Lancet. 2018 Apr 28;391(10131):1683-1692. doi: 10.1016/S0140-6736(18)30295-2. Epub 2018 Apr 26. Erratum in: Lancet. 2018 Jun 23;391(10139):e24. doi: 10.1016/S0140-6736(18)31323-0. PMID: 29726344.
Blumberger DM, Mulsant BH, Thorpe KE, McClintock SM, Konstantinou GN, Lee HH, Nestor SM, Noda Y, Rajji TK, Trevizol AP, Vila-Rodriguez F, Daskalakis ZJ, Downar J. Effectiveness of Standard Sequential Bilateral Repetitive Transcranial Magnetic Stimulation vs Bilateral Theta Burst Stimulation in Older Adults With Depression: The FOUR-D Randomized Noninferiority Clinical Trial. JAMA Psychiatry. 2022 Nov 1;79(11):1065-1073. doi: 10.1001/jamapsychiatry.2022.2862. PMID: 36129719; PMCID: PMC9494264.
This article is for general education and is not medical advice. TMS suitability depends on an individual clinical evaluation; talk with a qualified clinician about your specific history.
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