Common effects
What most people feel during a TMS course
The pooled safety analysis of the pivotal trials covered 325 patients at 23 sites and more than 10,000 treatment sessions. Transient headaches and scalp discomfort were the most common effects, there were no seizures and no deaths, and 4.5 percent of patients discontinued acute treatment because of an adverse event.
TMS is given awake, in a chair, with a magnetic coil resting against the scalp over the left prefrontal cortex. Each pulse makes a loud click and a tapping sensation, and the muscles of the scalp and face can contract with it. That is why the effects cluster where the coil sits. In the 301-patient randomized trial that led to the first FDA clearance, the authors described adverse events as generally mild and limited to transient scalp discomfort or pain. Tingling or twitching of facial muscles and brief lightheadedness can also occur during treatment.
Scalp discomfort or pain
Felt at the coil site during pulses. Usually strongest in the first week and eases as the scalp adapts. The team can adjust coil position and, within protocol, the intensity ramp.
Headache
Typically mild, during or after a session, and short-lived. In older adults it was the single most reported effect, at 6.9 percent of patients.
Facial twitching and tingling
Muscle contraction in the forehead, eyelid, or jaw with each pulse train. It stops when the pulses stop.
Lightheadedness and noise
Brief lightheadedness after standing up from the chair, and the sound of the coil, which is why earplugs are used at every session.
Common effects are often strongest in the first sessions. Tell the team if scalp pain is not easing; coil placement and the intensity ramp can be reviewed within the prescribed protocol.
Treatment schedules
Standard courses and accelerated TMS are different schedules
A standard course for major depressive disorder (MDD) is commonly 36 sessions. A standard OCD course is commonly planned as 30 sessions over six weeks. The indication, device, response, and tolerability determine the actual plan.
| Treatment | Typical course | What to confirm |
|---|---|---|
| Standard TMS for MDD | 36 sessions, often 30 weekday treatments followed by 6 taper sessions. | The 2025 professional consensus encourages completing 36 sessions unless worsening or intolerance requires a different plan. |
| TMS for OCD | 30 sessions over about six weeks; the pivotal deep-TMS study used 29 sessions. | Ask which OCD-specific device and protocol are being used. A depression protocol is not automatically an OCD protocol. |
| SAINT for depression | 50 sessions over five days: 10 sessions each day, with scheduled breaks. | SAINT uses individualized MRI-guided targeting and a specific protocol. Other accelerated courses are not interchangeable with SAINT. |
Several accelerated protocols have supporting research. SAINT is a well-studied example with both open-label and randomized sham-controlled trials. Ask the clinician which evidence supports the exact protocol offered, how side effects will be monitored, and what follow-up is planned. Session counts describe a course, not instructions to change your own treatment.
Schedule sources: the 2025 depression consensus, the Clinical TMS Society SAINT statement, the BrainsWay OCD patient manual, and the Carmi OCD trial linked below. Your team can confirm the exact number of visits, including any taper or follow-up.
Rare and serious risks
Seizure, mania, and hearing: what the numbers actually are
A 2019 survey of 174 active laboratories and clinics counted 24 seizures across about 318,560 TMS sessions delivered between 2012 and 2016, a rate of 0.08 per 1,000 sessions. When stimulation stayed within published guidelines and the person had no risk factors, only 4 seizures occurred, which is fewer than 1 per 60,000 sessions.
Three details from that survey matter for anyone weighing treatment. Risk factors such as a brain lesion or epilepsy raised the risk substantially. Seizures were more common when guideline limits were exceeded. And they were most likely in the first few exposures, which is why the first sessions are the ones to watch most closely. The 2021 international safety guidelines, updating the 2009 consensus, describe the risk of seizure as low, even in patients taking drugs that act on the central nervous system, at least with traditional stimulation parameters and focal coils. In the earlier pooled analysis of the pivotal trials, more than 10,000 sessions produced no seizures at all.
Mania or hypomania is another uncommon event reported during TMS treatment. International safety guidance discusses these mood switches, including in people with bipolar disorder. This is the reason a history of elevated mood is part of the screening conversation and part of what the team watches during the course, and it is the honest answer to the search for whether TMS can make bipolar disorder worse: it can trigger an elevated episode in susceptible people, and that is managed by screening and monitoring, not by pretending it does not happen.
Hearing also needs protection. International safety guidelines recommend well-fitted ear protection because repeated coil clicks can damage hearing without it. In the pooled trial analysis, auditory thresholds did not change, which is what you would expect when ear protection is used at every session. Ask to see the earplugs before the first pulse.
Older adults
Side effects of TMS after age 60
A systematic review pooled 11 studies of TMS in 353 adults over 60 with late-life depression. Adverse events were reported in 12.4 percent of patients and serious adverse events in 1.5 percent.
The common effects were the same as in younger adults: headache in 6.9 percent and discomfort at the stimulation site in 2.7 percent. The serious events were three psychiatric hospitalizations, one case of increased suicidal ideation, and one posterior vitreous detachment with a retinal tear. The authors concluded that TMS in older adults is generally well tolerated, and the numbers are the reason a TMS course in an older patient should come with a named clinician who checks mood at every visit, not only at the end. Our comparison of ECT and TMS covers how the two brain-stimulation options differ in setting, anesthesia, memory effects, and speed, which is often the real question in late-life depression.
Feeling worse
What it means when TMS seems to make things worse
Two separate experiences get described in the same words, and they call for different responses. One is a course that does not work. The other is a course during which mood, sleep, or thoughts of self-harm get worse. Both should be reported to the treating clinician promptly, but the second one the same day.
A course may not produce a response. In a study of 307 outpatients at 42 practices in the United States, patients who had failed an average of 2.5 adequate antidepressant trials received a course of TMS. Clinicians rated 58.0 percent as responders and 37.1 percent as in remission at the end of the course; on patient-rated scales the response rate was 41.5 to 56.4 percent. That is a real result for a population that had already exhausted several medications, and it also means roughly four in ten people finished five weeks of daily sessions without a response. These response rates do not explain any individual report of harm. Lack of benefit, worsening symptoms, and lasting symptoms each deserve a reassessment with the treating clinician.
Getting worse during the course is different. The published trials did not define a temporary dip as an outcome; what they tracked, as the pooled safety analysis describes, was whether depressive symptoms worsened during treatment as a disease-specific risk, and the trials reported no meaningful worsening on average. Some clinic websites state that around a fifth of their own patients feel worse in the second or third week. That is a clinic observation, not a trial finding, and it should not be used to talk anyone out of reporting a change. A steady worsening, a new or stronger wish to be dead, or a sudden lift into unusually high energy and little need for sleep are each a reason to contact the team before the next session.
- Keep a two-line daily log through the course: how the scalp felt, and one mood number on the same scale each day.
- Report worsening mood promptly; do not wait for a particular score or number of days.
- Report any thought of suicide the same day. If you cannot reach the team, call or text 988.
- Report any sudden high: sleeping far less, racing thoughts, unusual spending or plans. This matters most if you or a relative has bipolar disorder.
- Ask at the halfway point what the team is seeing on their own scale, and what would change the plan.
Long-term effects
Does TMS cause permanent side effects?
Clinical studies using recommended TMS protocols have not established lasting cognitive impairment or cumulative toxicity. In the pooled analysis of 325 patients and more than 10,000 sessions, cognitive function and hearing thresholds did not change during acute treatment, extended treatment, or reintroduction.
The Clinical TMS Society reports no demonstrated toxicity from extended treatment, and the 2024 professional practice guidelines report no cognitive impairment in trials using recommended parameters. These findings are reassuring; they are not a guarantee that every person will remain free of symptoms. A 2025 adverse-effects review describes uncommon cognitive complaints that are generally mild or transient.
Tell the treating psychiatrist about any new or persistent change in memory, concentration, mood, or hearing so it can be assessed. Continue using ear protection and the agreed safety plan throughout the course.
Before the first session
Who needs extra screening before TMS, and why
The rare risks on this page are managed by what the team knows before the first pulse. The Clinical TMS Society and international safety guidance describe screening that covers metal in or near the head, seizure history, mood history, and medications.
| Tell the team about | Why it matters | What usually happens |
|---|---|---|
| Metal or implants in or near the head | Metal and electronic implants can interact with the magnetic field. Disclose aneurysm clips or coils, stents, stimulators, pacemakers, cochlear implants, and metal fragments; the team must check the exact device and location. | Some implants rule TMS out; others need a device-specific check. Dental fillings and braces are generally not a problem, but say so anyway. |
| Seizures, epilepsy, or a brain injury | In the 2019 survey, brain lesions and epilepsy raised seizure risk substantially, and most seizures happened in the first few exposures. | Individual risk assessment; sometimes a different treatment. If TMS goes ahead, the early sessions are watched closely and guideline limits are not exceeded. |
| Bipolar disorder or any past high | TMS can trigger mania or hypomania, particularly in people with bipolar disorder. | Mood-stabilizing medication is reviewed and mood is checked at every visit, with a plan for what to do if energy climbs. |
| Frequent headaches or migraine | Headache is the most common side effect and can be harder to sort from a baseline headache disorder. | A headache baseline is recorded before the first session so a change is visible. |
| Pregnancy, or planning one | Tell the team if you are pregnant or planning pregnancy. Professional guidance recommends an individualized discussion of treatment, positioning, and monitoring. | A conversation about timing and alternatives with the psychiatrist and the obstetric team. |
| Every medication, including sleep aids and stimulants | Some drugs lower the seizure threshold. The 2021 guidelines still describe the risk as low, but the team needs the full list to say so for you. | The list is reviewed before the first session and again if anything changes during the course. |
These are the same questions that decide whether TMS is the right next step at all. Our TMS overview covers how the treatment works and who it is for, and the treatment-resistant depression hub covers the reassessment that should happen before any brain-stimulation course. If cost is the question underneath, the TMS cost and insurance guide is the place to price a full course before committing to it.
Printable
Your TMS side-effect log
Fill in the first three lines before the first session. Fill in the rest every day of the course, and bring the sheet to the halfway check and the last visit.
- Baseline before session one: usual headache frequency, sleep hours, and your mood number on the scale the clinic uses.
- Screening confirmed: metal and implants disclosed, seizure and mood history disclosed, full medication list reviewed, earplugs shown.
- The name and daytime number of the clinician who owns this course, and the after-hours number.
- Each session: scalp discomfort from 0 to 10 during pulses, headache afterward yes or no and how long, any facial twitching or lightheadedness.
- Each day: one mood number, hours slept, and one word for energy. Note changes and report worsening mood promptly.
- Any thought of suicide, any new high, any fainting or unusual event during a session: date, what happened, who you told and when.
- Halfway check: what the team sees on their scale, whether coil position or the intensity ramp was changed, and what would change the plan.
- End of course: response or not in the team’s words, what the next decision is, and the date of the follow-up visit.
Common questions
TMS side effects: questions people ask
What are the most common side effects of TMS?
Scalp discomfort or pain at the stimulation site and headache. In the pivotal randomized trial of 301 medication-free patients, adverse events were described as generally mild and limited to transient scalp discomfort or pain, and 4.5 percent of patients stopped active treatment because of an adverse event. In the pooled safety analysis of 325 patients and more than 10,000 sessions, transient headaches and scalp discomfort were the most common effects. Muscle twitching or tingling around the coil and brief lightheadedness can also occur. These effects usually happen during or shortly after a session and tend to ease over the first week or two.
Can TMS make you feel worse at first?
Some people do feel worse in the early weeks, and it is worth taking seriously rather than waiting out. The published trials did not measure a 'dip' as a distinct outcome; what they tracked was whether depressive symptoms worsened during treatment, and they reported no meaningful worsening on average. Clinic websites that say a fifth of their patients feel worse around week two are describing their own experience, not a trial finding. If your mood, sleep, or thoughts of self-harm get worse during a course, tell the treating clinician the same day. That is a clinical decision point, not a normal phase to push through.
Does TMS get worse before it gets better?
Not as a rule. Headache and scalp discomfort are most noticeable in the first sessions and usually fade as the scalp adapts. With a standard daily course, improvement may build over several weeks. Accelerated protocols use a different schedule; neither schedule guarantees a response. A temporary period of feeling flat or discouraged partway through a course is reported by patients but has not been measured as a predictable stage in the controlled trials. A steady worsening, or any new thoughts of suicide, should be reported immediately.
Can TMS cause permanent side effects?
Available clinical studies have not established lasting cognitive impairment or cumulative toxicity from TMS delivered within recommended protocols. In the pooled analysis of 325 patients and more than 10,000 sessions, cognitive function and hearing thresholds did not change. This does not mean every symptom or rare adverse event is impossible: a recent safety review describes uncommon, usually mild or transient cognitive complaints. Tell the treating clinician about any persistent change in memory, concentration, mood, or hearing. Ear protection remains necessary at every session.
Is TMS safe for depression?
The updated depression consensus supports a standard course of 36 sessions when tolerated, and the 2021 international safety guidelines describe seizure risk as low, even in patients taking drugs that act on the central nervous system, when traditional stimulation parameters and focal coils are used. Safe does not mean risk-free: seizures, mania in people with bipolar disorder, and hearing damage without ear protection are the recognized rare risks, and screening before treatment is how they are managed.
How likely is a seizure from TMS?
A 2019 survey of 174 laboratories and clinics counted 24 seizures across about 318,560 TMS sessions between 2012 and 2016, which is 0.08 seizures per 1,000 sessions. When stimulation stayed within published guidelines and the person had no risk factors, only 4 seizures occurred, fewer than 1 per 60,000 sessions. Risk factors such as a brain lesion or epilepsy raised the risk substantially, seizures were more common when guideline limits were exceeded, and they were most likely in the first few exposures. In the earlier pooled trial analysis of more than 10,000 sessions there were no seizures at all.
Can TMS make bipolar worse?
It can trigger an emotional high, called mania or hypomania, particularly in people with bipolar disorder, so international safety guidance calls for attention to mood changes and a history of bipolar disorder during screening and treatment. A bipolar diagnosis does not automatically rule TMS out, but it changes how closely mood is watched during the course and what medication is in place. Tell the team about any past episode of elevated mood, reduced need for sleep, or racing thoughts, even one that was never formally diagnosed.
What is the controversy with TMS, and why do some people say it ruined their life?
Two different things get mixed together in those accounts. The first is non-response: in a study of 307 patients at 42 practices, 58 percent responded and 37 percent reached remission, which means roughly four in ten people finished a course without a meaningful improvement, often after paying and rearranging five weeks of daily life. The second is a report of lasting symptoms or harm. The studies summarized here cannot explain an individual report or establish how often those reports occur; symptoms deserve a clinical assessment. If you are in either group, the next step is a reassessment with the treating psychiatrist, not a second course on faith. Our treatment-resistant depression hub and our comparison of TMS, SPRAVATO, and ketamine cover what the alternatives look like.
Sources
What this page is built on
- Janicak PG, O'Reardon JP, Sampson SM, and colleagues. Transcranial magnetic stimulation in the treatment of major depressive disorder: a comprehensive summary of safety experience from acute exposure, extended exposure, and during reintroduction treatment. Journal of Clinical Psychiatry. 2008;69(2):222-232.
- O'Reardon JP, Solvason HB, Janicak PG, and colleagues. Efficacy and safety of transcranial magnetic stimulation in the acute treatment of major depression: a multisite randomized controlled trial. Biological Psychiatry. 2007;62(11):1208-1216.
- Lerner AJ, Wassermann EM, Tamir DI. Seizures from transcranial magnetic stimulation 2012-2016: results of a survey of active laboratories and clinics. Clinical Neurophysiology. 2019;130(8):1409-1416.
- Rossi S, Antal A, Bestmann S, and colleagues. 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(1):269-306.
- Overvliet GM, Jansen RAC, van Balkom AJLM, and colleagues. Adverse events of repetitive transcranial magnetic stimulation in older adults with depression, a systematic review of the literature. International Journal of Geriatric Psychiatry. 2021;36(3):383-392.
- Carpenter LL, Janicak PG, Aaronson ST, and colleagues. Transcranial magnetic stimulation (TMS) for major depression: a multisite, naturalistic, observational study of acute treatment outcomes in clinical practice. Depression and Anxiety. 2012;29(7):587-596.
- Perera T, George MS, Grammer G, Janicak PG, Pascual-Leone A, Wirecki TS. The Clinical TMS Society consensus review and treatment recommendations for TMS therapy for major depressive disorder. Brain Stimulation. 2016;9(3):336-346.
- Clinical TMS Society: Patients and Families — treatment courses, side effects, cognition, and screening.
- Consensus review and considerations on TMS to treat depression: update endorsed by the NNDC, Clinical TMS Society, and IFCN. 2025.
- Clinical TMS Society: Revised statement regarding the SAINT protocol. August 7, 2024.
- BrainsWay: Deep TMS for obsessive-compulsive disorder — patient manual and treatment schedule.
- Carmi L and colleagues. Efficacy and safety of deep transcranial magnetic stimulation for obsessive-compulsive disorder: a prospective multicenter randomized double-blind placebo-controlled trial. American Journal of Psychiatry. 2019.
- Royal Australian and New Zealand College of Psychiatrists: Professional practice guidelines for the administration of repetitive transcranial magnetic stimulation. 2024.
- Monitoring adverse effects in TMS: From controlled trials to clinical reality. Current Opinion in Psychology. Published online 2025.
Original study figures were checked September 19, 2026. Safety guidance and treatment-schedule sources were rechecked for this September 21, 2026 revision. Rates are study averages from trial and survey populations and do not predict any one person’s course. This page is educational and does not replace the advice of the treating team.