TMS Therapy Side Effects: What's Common and What's Rare

Most TMS therapy side effects are limited to scalp discomfort and headache during the first week, and both usually fade. In the trials behind FDA clearance, 4.5 percent of patients stopped treatment because of an adverse effect. Seizure is the serious risk, and it’s rare enough that a safety review of over 10,000 sessions recorded none.

Below we walk through what patients actually report, what the numbers say, which risks belong to other treatments rather than this one, and what your provider does to make each session easier.

What Are the Most Common TMS Therapy Side Effects?

Transcranial magnetic stimulation sends focused magnetic pulses through the scalp to a target area of the brain. Because the coil sits against your head and the pulses are felt, the common side effects are local rather than systemic.

Two reactions lead the list. Scalp discomfort at the treatment site is the first. A tapping, pinching, or tightening feeling under the coil is what most patients describe. Headache after a treatment session is the second, and it usually responds to a standard over-the-counter pain reliever.

A safety analysis pooling 325 patients across 23 sites in the United States, Australia, and Canada found that transient headaches and scalp discomfort were the most common adverse events. Most were mild to moderate. Across more than 10,000 cumulative treatment sessions in that program, there were no deaths and no seizures.

Both of those reactions come from the pulses themselves rather than from anything entering your body. That distinction shapes the whole profile, and in our experience it is the first thing we have to explain in the consult room.

Other reported effects are less frequent: facial muscle twitching during the pulses, jaw or tooth ache, watering eyes, and lightheadedness right after standing. The clicking noise of the coil can also bother sensitive ears, which is why earplugs are standard.

We compared TMS therapy with two other options for severe depression, because the differences show up in daily life rather than on a symptom scale.

That table is the reason many patients ask about TMS after years of trying medication. A treatment with local side effects behaves very differently in daily life from one you swallow every morning.

How Long Does Scalp Discomfort Last?

Usually days, not weeks.

Two things change over the first sessions. Your scalp adapts to a sensation it has never felt before, and your provider tunes the settings. Both work in your favor.

The safety data describes a largely predictable time course of resolution for the most common adverse events. In plain terms, session five tends to feel easier than session one. Many of our patients say the first two or three are the ones to get through.

Practical adjustments help too:

• Small changes to coil position spread the sensation over a wider area.
• Ramping intensity up gradually across early sessions lets your scalp adjust.
• A pain reliever taken about an hour before a session takes the edge off for some people.
• Telling the TMS technician exactly where it pinches lets them fix it during the session, not after.

So say something at the time. There’s nothing to prove by sitting through discomfort quietly, and a small change often solves it.

One more note on headache, since it’s the reaction patients ask about most. It tends to appear after the session rather than during it, and it usually responds to the same pain reliever you’d take for any other headache. Ask your provider before taking anything, since a few options interact with medications you may already be on.

What Is the Real Seizure Risk With TMS?

Seizure is the most serious acute adverse effect linked to repetitive transcranial magnetic stimulation. It’s also uncommon enough that most clinicians in the field have never seen one.

A 2009 international safety consensus reviewing a decade of research and clinical use reported that seizure “has been extremely rare, with most of the few new cases receiving rTMS exceeding previous guidelines”. Those cases often involved patients already taking drugs that lower the seizure threshold, which is the practical part.

That gives you a practical checklist rather than a vague worry. Risk rises when:

• Stimulation parameters exceed published safety limits.
• A patient takes medication that lowers the seizure threshold, including some antidepressants and stimulants.
• There’s a personal history of seizure or epilepsy.
• Alcohol or benzodiazepine withdrawal is underway.
• Sleep deprivation is severe on the day of treatment.

None of these rule out treatment automatically. They change the conversation you have before the first tms session, and they’re part of why a psychiatric evaluation comes first.

A tms induced seizure, if it happened, would occur during the session with staff present, which is another argument for treatment in a clinical setting rather than anywhere less supervised.

Does TMS Cause Memory Loss or Brain Damage?

No evidence supports either, and this worry usually comes from confusion with electroconvulsive therapy.

But the two treatments aren’t close relatives. ECT induces a seizure under general anesthesia, and memory effects around treatment sessions are well documented. TMS uses magnetic pulses while you sit awake in a chair, with no anesthesia and no induced seizure.

Formal testing backs that up. In the clinical development program, cognitive function did not change across acute exposure, extended exposure, and reintroduction treatment. Auditory threshold did not change either, which addresses the worry about the coil’s clicking noise.

Brain damage isn’t a documented outcome of TMS treatment at approved parameters. The magnetic field falls off quickly with distance and reaches only a few centimeters into the cortex.

One real effect deserves a mention, since it’s specific rather than vague. In people with bipolar disorder, any antidepressant treatment carries some risk of triggering a manic or hypomanic switch. That’s a reason for careful screening and monitoring rather than a reason to avoid the treatment option outright.

Are There Long Term Side Effects From TMS?

None have been established, and the safety work looked for them in three separate settings.

The clinical development program tracked adverse events during acute treatment, during extended exposure over a longer period, and during reintroduction, meaning a second course after the first one ended. Cognitive function was tested formally across all three. It stayed stable. Hearing threshold stayed stable as well.

More accurately, that’s a narrower claim than “there are no long term side effects,” and we’d rather be accurate than reassuring. What the data supports is this: across a large program with more than 10,000 treatment sessions, no pattern of lasting harm appeared, and no deaths or seizures occurred.

Reintroduction matters to patients more than it sounds. Depression comes back for a large share of patients, and a second course of tms treatment is common. The safety profile held up on repeat exposure, which is a fair question to ask before you start something you may repeat in two years.

What we don’t have is decades of follow-up on people who received many courses over a lifetime. Ask your provider what’s known and what isn’t, and treat any clinic that promises certainty here with some suspicion.

Which Side Effects Does TMS Not Have?

Sometimes the useful list is the one that stays empty. Compared with antidepressant medication, TMS therapy typically does not cause:

• Weight gain or appetite changes.
• Sexual dysfunction.
• Dry mouth, constipation, or stomach upset.
• Daytime sedation or morning grogginess.
• Withdrawal symptoms when you finish the course.

That last point surprises people. Because nothing is circulating in your bloodstream, there’s no discontinuation syndrome at the end of a course of tms treatment.

There’s also no daily pill to remember and no interaction list to manage against your other medications, which matters for anyone already treating more than one mental health condition.

Who Should Be Screened Extra Carefully?

Certain situations call for a closer look before the first pulse.

Metal in or near the head is the main hard stop. Aneurysm clips, coils, stents, stimulator electrodes, cochlear implants, and bullet or shrapnel fragments near the treatment area rule out treatment or require specialist review. Dental fillings and most orthodontic work are fine.

Other factors that shape the plan include a seizure or epilepsy history, a history of head injury or stroke, current medications that lower the seizure threshold, pregnancy, and a diagnosis of bipolar disorder. Hearing loss is worth mentioning too, so your team can pay extra attention to ear protection.

Bring your full medication list to the evaluation, including anything from another prescriber. Interactions with TMS aren’t chemical, but the seizure threshold question is real.

What Does a Course of Treatment Involve?

Standard prefrontal TMS therapy runs daily on weekdays for 4 to 6 weeks, which works out to roughly 20 to 30 sessions, according to the Clinical TMS Society consensus review. In the multisite randomized trial, sessions ran five times a week at 10 pulses per second and 120 percent of motor threshold, delivering 3,000 pulses per session over 4 to 6 weeks.

The first visit is longer than the rest, because your provider maps your motor threshold and finds the right coil position for you. After that, a session is a seated appointment in a treatment room. You stay awake, you can talk, and most patients drive themselves home afterward.

One note on access. TMS needs a coil, a mapped motor threshold, and daily visits. At Foundation Medical Group it runs from the Richmond, VA clinic rather than from the Dallas, Texas, Decatur, Georgia, or American Fork, Utah offices, which provide psychiatry and medication management. Newer variations exist, including deep TMS with a different coil design and accelerated TMS protocols that compress many sessions into a few days. Side effect profiles differ somewhat between them, so ask specifically about the protocol your clinic uses rather than assuming they match.

If depression symptoms haven’t responded to two or more antidepressants, TMS is one of the treatments worth discussing. Spravato is another, with a very different risk profile, and comparing the two honestly is a normal part of a psychiatric evaluation.

What Does a TMS Session Feel Like?

Honestly? Patients ask us this more than they ask about risk. The two questions are related. Knowing what’s coming makes the tapping easier to sit with.

You sit in a chair, upright, in your own clothes. A padded arm holds the tms coil against one spot on your head. Nothing goes into your arm. Nothing puts you to sleep.

The machine clicks in short bursts. You feel a tap on your scalp with each pulse. Then a pause. Then another burst. A session runs in that rhythm for most of the appointment.

Some people feel a twitch at the corner of the eye or the jaw. That’s a nerve near the surface responding to the pulse, and it stops when the burst stops.

You wear earplugs the whole time. The clicking is loud, and hearing protection is standard for that reason. Formal testing found no change in hearing threshold across the trial program, and the earplugs are part of why.

You can talk between bursts. Many patients read, listen to music, or chat with the tms technician. Others just close their eyes.

When it’s over, you stand up and go. There’s no recovery room and no waiting period. Most people drive themselves back to work.

Our team in Richmond, VA blocks the first appointment longer than the rest. Mapping takes time, and rushing it is how a course of magnetic stimulation ends up less comfortable than it needs to be.

How Do We Keep Side Effects Low?

Small adjustments do most of the work. And they happen session by session, not in one big fix.

We start intensity lower and build it up over the first few visits. Your scalp gets used to the feeling that way, instead of meeting full strength on day one.

We move the coil in small steps if one spot stays sore. A shift of a few millimeters can spread the sensation and settle it.

We ask you to eat and drink before you come. Low blood sugar makes a session feel worse. So does a poor night of sleep, which matters more here than most patients expect.

We check your medication list at each visit. A new prescription from another doctor can change your seizure risk, and we would rather hear about it early.

And we ask you to speak up during the session. Adverse events that get reported get fixed. The ones patients keep to themselves turn into a reason to quit in week two, which is a shame when the fix takes a minute.

Most common TMS side effects respond to one of those five levers. Mild side effects that persist past the first week are worth a longer conversation about parameters.

More Questions About TMS Side Effects

Can I keep taking my antidepressant during TMS?

Usually yes. Tell your provider about every medication you take, since a few lower the seizure threshold and may change how your parameters are set.

Will I feel worse before I feel better?

Most patients don’t. Some notice more fatigue in the first week, alongside the scalp discomfort, and it typically settles as treatment continues.

Do side effects mean it’s working?

No. Discomfort tracks coil position and intensity, not response. Some patients feel very little and still see their depressive symptoms improve.

Is TMS safe if traditional treatments made me feel awful?

Often that’s the reason people come. TMS therapy doesn’t share the side effect profile of a daily pill, so a bad run with medication tells you little about how you’ll do here.

What should I report right away?

Tell your team about severe or worsening headache, any episode of losing awareness, new hearing changes, or a sudden lift into unusual energy and sleeplessness, which can signal a manic switch.

Key Takeaways

• Scalp discomfort and headache are the most common TMS therapy side effects, and both are usually mild.
• Only 4.5 percent of patients discontinued treatment because of an adverse effect in the trials behind FDA clearance.
• A safety review across more than 10,000 sessions recorded no deaths and no seizures.
• Seizure is the most serious acute risk and is described as extremely rare in the international safety consensus.
• Most reported seizure cases involved parameters beyond published limits or drugs that lower the threshold.
• Cognitive function and hearing thresholds showed no change on formal testing.
• TMS uses no anesthesia and induces no seizure, unlike electroconvulsive therapy.
• Weight gain, sexual dysfunction, and withdrawal effects are not part of the profile.
• Metal implants near the head, seizure history, and bipolar disorder all need screening first.

Talk With Foundation Medical Group in Richmond

Worrying about side effects is a reasonable thing to do before starting any treatment. Our physician-led team in Richmond, Virginia will go through your history, your medication list, and your own risk factors, then tell you plainly whether TMS therapy is a sensible next step.

Read more about TMS for depression, TMS for anxiety, and whether insurance covers TMS. When you’re ready, our Richmond TMS team can answer the rest.

Sources

• Janicak et al, safety of TMS in major depressive disorder, J Clin Psychiatry 2008.
• O’Reardon et al, multisite randomized controlled trial of TMS, Biol Psychiatry 2007.
• Rossi et al, safety and application guidelines for TMS, 2009.
• Perera et al, Clinical TMS Society consensus review, 2016.
• Repetitive Transcranial Magnetic Stimulation, StatPearls, NCBI Bookshelf.
• National Institute of Mental Health, Brain Stimulation Therapies.