TMS & Neuromodulation · Part 5

Overview

Transcranial magnetic stimulation (TMS) has a favorable safety profile when a qualified team uses an appropriate, device-authorized protocol after careful screening. Most adverse effects are brief and local—scalp discomfort, headache, facial-muscle contraction, or fatigue. The most serious recognized risk is a seizure, which is rare but not zero.¹²

Safe treatment begins before the first pulse. The clinician must confirm the diagnosis, decide whether routine outpatient TMS matches the urgency and complexity of the illness, review medications and substance use, distinguish fainting from seizure history, and identify metal or electronic implants that could interact with the magnetic field. FDA labeling differs by device and coil, so there is no single universal contraindication list that can replace review of the exact system’s instructions for use.¹³

The most important points are:

• A good candidate has both an appropriate indication and an appropriate level of clinical stability. TMS should not be selected solely because a person prefers a technology over a full diagnostic evaluation.
• Implant screening is essential. Conductive, ferromagnetic, or magnet-sensitive material and active electronic devices in or near the stimulation field may be unsafe; compatibility must be confirmed for the exact device and location.¹³
• Seizure is rare, not impossible. In a survey covering 586,656 sessions, 18 seizures were reported—0.31 per 10,000 sessions overall—with higher risk for some coils and in patients with risk factors.²
• Fainting can resemble a seizure. A careful history can prevent unnecessary exclusion and helps the treatment team prepare appropriately.¹
• Bipolar disorder, psychosis, pregnancy, adolescence, older age, and neurological illness require individualized review. They are not all automatic exclusions.
• TMS is not emergency care. Imminent suicide risk, catatonia, psychotic depression, severe self-neglect, or inability to maintain food or fluids may require emergency treatment or a faster intervention.⁴

Evidence cutoff: This article reflects publicly available evidence and U.S. regulatory information through August 9, 2026. Final eligibility depends on the diagnosis, the complete treatment protocol, the patient’s circumstances, and the current labeling of the specific TMS system.

---

Who Is Commonly Considered for TMS?

For major depressive disorder—the most established use—TMS is commonly considered when an adult has not achieved satisfactory improvement from one or more adequate antidepressant trials in the current episode or cannot tolerate medication. Some systems also have device-specific indications for adjunctive treatment of major depression in patients ages 15 through 21.³⁵

A strong evaluation asks more than whether medications “failed.” It considers:

• whether the diagnosis is major depression, bipolar depression, grief, adjustment disorder, substance-induced symptoms, a neurological condition, or another syndrome;
• the adequacy and tolerability of medication and psychotherapy trials;
• current symptom severity, psychosis, catatonia, agitation, and suicide risk;
• medical, neurological, sleep, hormonal, and substance-related contributors;
• the patient’s goals, schedule, transportation, and ability to complete a treatment course;
• which device and protocol would be used and whether that use is FDA-authorized or off-label.

Patients with an FDA-authorized indication may still be poor candidates for a particular protocol, and a person outside a common insurance definition may still deserve a thoughtful clinical discussion. Regulatory labeling, medical appropriateness, and insurance coverage are related but separate questions.

When Routine Outpatient TMS May Not Be the Right First Step

TMS can reduce depressive symptoms, but a standard outpatient course usually requires repeated visits and may take weeks to produce its full effect. It should not delay a higher level of care when the condition is immediately dangerous.

Seek urgent evaluation for imminent suicidal intent or inability to stay safe, violent or severely disorganized behavior, catatonia, severe psychosis, rapidly worsening mania, inability to eat or drink, severe dehydration or malnutrition, delirium, a new neurological deficit, or another medical emergency. In the United States, call 911 for an emergency or call/text 988 for the Suicide & Crisis Lifeline.

Electroconvulsive therapy (ECT) remains an important, often faster treatment for severe or psychotic depression, catatonia, and other urgent presentations. TMS and ECT should not be framed as interchangeable versions of the same treatment.⁴

Implants and Metal: The Most Important Hardware Screen

The coil creates a strong, rapidly changing magnetic field. Conductive or ferromagnetic material can experience induced current, heating, force, or torque; active electronic devices can malfunction or deliver unintended stimulation. The exact risk depends on the material, shape, location, distance from the coil, orientation, and the TMS system.¹

Items that require explicit review include:

• cochlear implants and other implanted hearing devices;
• deep-brain, cortical, vagus-nerve, spinal-cord, or peripheral-nerve stimulators;
• aneurysm clips or coils, intracranial stents, embolization material, or vascular hardware;
• implanted pumps, programmable shunts, or medication-delivery systems;
• metal plates, screws, meshes, or fragments in the head or neck;
• retained shrapnel or occupational metal exposure involving the eyes or head;
• cardiac pacemakers, defibrillators, loop recorders, or other electronic implants;
• wearable medical devices that may need to be removed or kept outside the field.

MRI-conditional does not automatically mean TMS-compatible. MRI and TMS expose a device to different field strengths, gradients, frequencies, and geometries. “Titanium” or “nonmagnetic” also does not settle the question because conductive hardware may still carry induced current. The treatment team may need the implant card, manufacturer, model number, operative report, imaging, and written compatibility information.

Ordinary dental fillings and most fixed dental work are commonly compatible because of their location and materials, but removable hearing aids, jewelry, hair clips, magnetic eyelashes, and other items near the coil should be removed as directed. Never assume compatibility from a general internet list.

Neurological and Seizure-Risk Assessment

A previous seizure does not always make TMS impossible, but it changes the risk-benefit analysis. The clinician should review:

• epilepsy diagnosis, seizure type, frequency, cause, and date of the last event;
• prior brain injury, stroke, tumor, infection, neurosurgery, or structural lesion;
• electroencephalogram and imaging results when relevant;
• anti-seizure medication adherence and recent dose changes;
• fever, electrolyte disturbance, severe sleep deprivation, or acute medical illness;
• alcohol, benzodiazepine, or sedative withdrawal;
• stimulants, recreational substances, or other exposures that may change seizure threshold.

The 2021 international expert guideline emphasizes that seizure risk arises from a combination of the protocol and the patient’s current state rather than from one binary factor.¹ A patient with stable, treated epilepsy may sometimes undergo TMS in an experienced setting after neurological review; another patient without epilepsy may be temporarily unsafe because of withdrawal, acute intoxication, or severe sleep deprivation.

How Rare Is a TMS-Associated Seizure?

Seizure is the most serious recognized acute adverse event of routine therapeutic TMS. A Clinical TMS Society survey reported 18 seizures across 586,656 sessions and 25,526 patients, equivalent to 0.31 seizures per 10,000 sessions overall. Rates differed by coil type and patient risk factors.²

Those numbers are useful for scale, not a personalized prediction. The risk for one patient depends on:

• the coil and complete pulse protocol;
• stimulation intensity and whether parameters remain within established safety limits;
• history of epilepsy or structural brain disease;
• medication changes and substance use;
• sleep deprivation, acute illness, metabolic disturbance, and withdrawal.

Most reported TMS-associated seizures have occurred during or immediately after stimulation and have been self-limited. A single provoked seizure does not necessarily mean that a person has developed epilepsy, but it requires medical assessment and re-evaluation before any further treatment.¹⁶

Fainting Is Different From a Seizure

Vasovagal syncope—fainting caused by a brief drop in blood pressure and heart rate—can occur around medical procedures and may include stiffening or a few brief jerks. Patients sometimes report that they “had a seizure” during a blood draw when the episode was actually fainting.

No single feature is definitive, and witness descriptions are often incomplete. The goal is not self-diagnosis but accurate history. Records from emergency care, neurology, or prior testing can be helpful.

Medication, Alcohol, Cannabis, and Other Substance Review

Many patients can continue prescribed psychiatric medications during TMS. The important safety rule is stability and disclosure, not an unsupervised medication washout. Report:

• all prescription drugs, over-the-counter products, and supplements;
• new medications or dose changes during the course;
• benzodiazepine, alcohol, or sedative reduction or withdrawal;
• stimulant use, including prescribed and nonprescribed products;
• cannabis and other recreational substances;
• major changes in caffeine, sleep, or nutrition.

Older warnings often classified long lists of medications as categorically unsafe. Current expert guidance places more emphasis on the full clinical context and on avoiding abrupt changes, intoxication, and withdrawal.¹ Never stop an antidepressant, benzodiazepine, anti-seizure medication, or other drug abruptly in order to “qualify” for TMS.

Bipolar Disorder, Mania, and Psychosis

A person presenting with depression may have unrecognized bipolar disorder. A careful history should ask about prior periods of decreased need for sleep, elevated or irritable mood, racing thoughts, impulsivity, increased goal-directed activity, psychosis, and family history. TMS has been studied in bipolar depression, but most U.S. depression clearances are for major depressive disorder, and treatment may be off-label depending on the system and diagnosis.

Treatment-emergent hypomania or mania appears uncommon, but it is clinically important. New reduced need for sleep, unusually high energy, agitation, risky behavior, grandiosity, pressured speech, or psychosis should prompt immediate reassessment rather than simply continuing the same protocol.⁷

Psychotic depression often needs a faster and more strongly established intervention such as ECT, particularly when severe. Routine outpatient TMS should not delay emergency or hospital-level treatment.⁴

Common Side Effects

A severe “worst headache,” persistent neurological deficit, prolonged confusion, loss of consciousness, chest pain, or another unusual symptom should not be dismissed as a routine side effect.

Memory and Thinking

Routine therapeutic TMS does not intentionally induce a seizure and does not usually produce the clinically significant memory adverse effects associated with ECT. Reviews of depression trials have generally found stable or modestly improved objective cognitive performance, often in parallel with improvement in depression.⁸

That evidence does not justify the absolute statement that TMS can never affect cognition. Depression, sleep loss, medication changes, anxiety, and neurological disease can all alter attention and memory. New or worsening cognitive symptoms deserve assessment rather than reassurance based only on a treatment category.

Hearing, Headache Disorders, and Sensory Sensitivity

Ear protection is required because the acoustic click can exceed safe exposure without attenuation. Patients with tinnitus, hyperacusis, migraine, or sensory sensitivity should discuss accommodations. TMS can sometimes trigger a headache, but a history of migraine is not automatically a contraindication. A new neurological aura, thunderclap headache, or major change in headache pattern warrants medical evaluation.

Pregnancy and Breastfeeding

TMS does not expose the fetus or breastfed infant to a circulating medication, which makes it an appealing option in some perinatal situations. Available case series, small trials, and systematic reviews have not identified a clear fetal safety signal, but the evidence is limited and underpowered compared with the adult depression literature. Pregnancy should therefore prompt coordinated review with the treating psychiatrist, obstetric clinician, and TMS team rather than a blanket declaration of safety or danger.⁹

Positioning, blood-pressure changes, sleep, nutrition, medication risk, illness severity, and the consequences of untreated depression all matter. Severe perinatal depression, psychosis, mania, or suicidality may require urgent hospital-based treatment.

Adolescents and Older Adults

In 2024, a specific NeuroStar label was expanded for adjunctive treatment of major depressive disorder in patients ages 15 through 21. This is not a universal pediatric indication for every TMS device or every depressive condition.⁵ Assessment should include development, family involvement, school function, substance use, bipolar risk, safety planning, and ongoing psychotherapy or medication care.

Older adults may be good candidates, including those who are sensitive to medication adverse effects. Age-related cortical atrophy can increase scalp-to-cortex distance and may influence dosing and response. Cognitive impairment, hearing, transportation, fall risk, medical comorbidity, and capacity for informed consent should be addressed.

What a High-Quality Safety Screen Should Include

1. Confirm the diagnosis and urgency. Determine whether routine outpatient TMS matches the illness and whether emergency or inpatient care is needed.
2. Review every implant and metal exposure. Obtain model-specific information rather than relying on “MRI-safe” or “titanium.”
3. Assess seizure and syncope history. Clarify what happened, identify current risk factors, and involve neurology when appropriate.
4. Review medications and substances. Document all changes throughout treatment.
5. Screen for bipolar disorder, psychosis, and substance withdrawal. These findings may change the diagnosis, setting, or treatment plan.
6. Establish a baseline. Record symptom severity, suicide risk, sleep, cognition when relevant, and functional goals.
7. Explain the exact protocol. The patient should know the device, coil, target, schedule, whether the use is on-label or off-label, common adverse effects, rare risks, and alternatives.
8. Create an event plan. Staff should know how to respond to syncope, seizure, acute psychiatric deterioration, or a medical emergency.¹¹⁰

Every item above is part of the structured screen performed before any course at our practice — outlined on the TMS program page.

Questions to Ask Before Starting

• What diagnosis and FDA-authorized or off-label indication are you treating?
• Which device, coil, target, and protocol will you use?
• Who performs the medical evaluation and supervises treatment?
• How did you evaluate my implants, seizure risk, medications, and bipolar risk?
• How will symptoms, functioning, and safety be measured?
• What would make you pause, change, or stop treatment?
• What is the plan if I worsen or do not respond?

Bottom line: TMS is generally well tolerated, and serious adverse events are uncommon when treatment follows established protocols with careful screening. Safety is not created by the machine alone. It depends on an accurate diagnosis, model-specific implant review, attention to seizure and withdrawal risks, ongoing psychiatric monitoring, trained staff, and a willingness to choose a different level of care when the situation is urgent.

Previous: TMS for Depression: What the Evidence Shows
Next: What to Expect During a Course of TMS Treatment

---

References

1. Rossi S, Antal A, Bestmann 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. Clin Neurophysiol. 2021;132(1):269-306. doi:10.1016/j.clinph.2020.10.003.
2. Taylor JJ, Newberger NG, Stern AP, Phillips A, Feifel D, Betensky RA, Press DZ. Seizure risk with repetitive TMS: survey results from over a half-million treatment sessions. Brain Stimul. 2021;14(4):965-973. doi:10.1016/j.brs.2021.05.012.
3. U.S. Food and Drug Administration. NeuroStar TMS Therapy System: 510(k) Summary (K083538). December 16, 2008.
4. National Institute of Mental Health. Brain Stimulation Therapies. Accessed July 10, 2026.
5. U.S. Food and Drug Administration. NeuroStar Advanced Therapy System: adjunctive major-depression treatment in patients ages 15 through 21 (K231926). March 22, 2024.
6. Lerner AJ, Wassermann EM, Tamir DI. Seizures from transcranial magnetic stimulation 2012-2016: results of a survey of active laboratories and clinics. Clin Neurophysiol. 2019;130(8):1409-1416. doi:10.1016/j.clinph.2019.03.016.
7. Xia G, Gajwani P, Muzina DJ, Kemp DE, Gao K, Ganocy SJ, Calabrese JR. Treatment-emergent mania in unipolar and bipolar depression: focus on repetitive transcranial magnetic stimulation. Int J Neuropsychopharmacol. 2008;11(1):119-130. doi:10.1017/S1461145707007699.
8. Martin DM, McClintock SM, Forster JJ, et al. Cognitive enhancing effects of rTMS administered to the prefrontal cortex in patients with depression: a systematic review and meta-analysis. Depress Anxiety. 2017;34(11):1029-1039. PMID:28543994.
9. Al-Shamali H, Hussain A, Dennett L, et al. Is repetitive transcranial magnetic stimulation (rTMS) an effective and safe treatment option for postpartum and peripartum depression? A systematic review. J Affect Disord Rep. 2022;10:100356. doi:10.1016/j.jadr.2022.100356.
10. McClintock SM, Reti IM, Carpenter LL, et al. Consensus recommendations for the clinical application of repetitive transcranial magnetic stimulation in the treatment of depression. J Clin Psychiatry. 2018;79(1):16cs10905. doi:10.4088/JCP.16cs10905.

Medical disclaimer. This article is provided for general educational and informational purposes only. It does not constitute individualized medical advice, diagnosis, treatment, a recommendation for any specific test or therapy, or informed consent. Medical information changes over time, and this article may not reflect developments occurring after its stated review date or apply to your individual circumstances. Do not disregard or delay professional medical advice, or start, stop, or change any medication or treatment, based on this article. Discuss personal medical decisions with a qualified healthcare professional who can evaluate your individual history and circumstances. Accessing or using this website does not, by itself, create a physician–patient relationship with Los Altos Neurology or any of its clinicians. Do not use this website for urgent or emergency medical concerns; call 911 or seek immediate emergency care. Although Los Altos Neurology makes reasonable efforts to provide accurate and current information, it does not guarantee that all content is complete, current, or applicable to every individual. See our full Medical Disclaimer.