Most people who undergo transcranial magnetic stimulation experience only mild, short-lived side effects, and serious events like seizures are rare when clinics follow standard screening protocols. Scalp discomfort and headache are the most common complaints, and both tend to fade within the first week or two of treatment. The rest of this guide walks through exact rates, who faces higher risk, and what your care team does to keep sessions safe.
TL;DR:
- The risk of seizure during TMS is extremely low, approximately 7 cases per 100,000 sessions, and most adverse events are mild and short-lived.
- Patients with implanted metal or electronic devices, seizure history, recent brain injury, certain medications, or lifestyle factors like alcohol use require careful screening or may be advised against TMS.
- Mild side effects like scalp tenderness and headaches usually occur during or shortly after sessions and can often be managed with over-the-counter pain relievers and proper precautions.
- Device type and protocol variations, such as deep TMS or theta-burst stimulation, may influence comfort but do not significantly alter overall safety risks.
- Most serious symptoms, including seizure activity lasting more than a few minutes or persistent hearing or visual disturbances, demand immediate medical attention.
Table of Contents
- Common Short-Term Side Effects of TMS
- Serious but Rare Adverse Events
- Who Should Avoid TMS or Proceed With Extra Caution
- Managing Side Effects During and After Sessions
- Does the TMS Device Type Change the Risk?
- What the Research Actually Shows About Frequency and Severity
- Warning Signs That Need Immediate Attention
- Weighing Rare Risks Against Real Benefit
- Getting Evaluated for TMS at Imindmental
- Sources
Common Short-Term Side Effects of TMS
The side effects you’re most likely to notice happen right where the magnetic coil touches your scalp. That’s not a coincidence. TMS delivers focused magnetic pulses to a specific region of the brain, and the tissue and muscles nearest the coil absorb most of the sensation.
Mayo Clinic lists the most frequently reported effects during and shortly after treatment:
- Scalp tenderness or a tingling sensation at the stimulation site
- Headache, usually mild to moderate and similar to tension headaches
- Facial muscle twitching, caused by pulses reaching nearby motor nerves
- Lightheadedness, especially after the first few sessions
- Temporary ringing or muffled hearing if ear protection isn’t worn correctly
These symptoms typically show up during the session itself or within a few hours afterward, and they usually ease as your brain and scalp adjust to repeated stimulation. Clinicians often see the sharpest drop in headache complaints between the second and fifth session. An over-the-counter pain reliever taken before or after treatment handles most of the discomfort. If a headache lingers for days, worsens rather than improves, or comes with vision changes, tell your treatment team right away rather than waiting for your next scheduled visit.
Serious but Rare Adverse Events
Seizure is the adverse event patients ask about most, and it’s also the rarest. Postmarketing surveillance puts the risk at roughly 7 seizures per 100,000 TMS sessions, a figure drawn from real-world device reporting rather than a controlled trial.
By the Numbers: Seizure risk during TMS runs under 1% overall across the published literature, and postmarketing data narrow that further to about 7 per 100,000 sessions, according to a literature review of TMS-related seizures.
Other serious events show up occasionally in case reports rather than large trials. These include psychiatric hospitalization, a temporary increase in suicidal thoughts, and, very rarely, ocular symptoms tied to stimulation near the eye. None of these appear with any regularity across the published record.
Interpreting these numbers requires a little caution. Case reports tend to overrepresent dramatic outcomes because unusual cases get published more often than routine ones. Some studies count events per session, while others count them per patient over a full course of treatment, and mixing those two denominators produces misleading comparisons. Underreporting is also a known limitation in postmarketing databases, since mild reactions rarely get logged at all.
Who Should Avoid TMS or Proceed With Extra Caution
Certain conditions raise your risk profile enough that your provider will screen for them before ever turning on the device. Some rule TMS out entirely; others just call for closer monitoring.
- Implanted metal or electronic devices near the head. Cochlear implants, aneurysm clips, and certain deep brain stimulators are absolute contraindications because the magnetic field can interact with metal or electronics.
- History of seizures or epilepsy. This doesn’t automatically disqualify you, but it raises your baseline risk and shapes how your provider sets stimulation intensity.
- Recent brain injury or neurosurgery. Healing tissue responds unpredictably to magnetic stimulation, so most clinics wait until recovery is well established.
- Certain medications. Drugs that lower seizure threshold, including some antidepressants and stimulants, factor into your provider’s risk calculation.
- Alcohol use and sleep deprivation. Both are recognized precipitating factors for seizure and worth disclosing honestly before treatment starts.
Standard screening covers a full medical and medication history, a motor threshold check to calibrate the right stimulation intensity for your brain, and verification that hearing protection fits properly. The IFCN consensus guidance on TMS safety treats this screening process as the backbone of safe practice, not an optional add-on.
Managing Side Effects During and After Sessions
Most of what keeps TMS side effects mild happens before you ever feel a pulse. Your provider titrates the magnetic intensity to your individual motor threshold rather than using a fixed setting, which limits unnecessary strength. Earplugs or protective headphones dull the clicking sound of the coil, and technicians can reposition the coil mid-session if a spot feels too sharp or uncomfortable.
- Take an OTC pain reliever before or after your appointment if headaches tend to hit you
- Ask your provider to lower intensity slightly if scalp discomfort feels sharper than expected
- Stay hydrated and avoid scheduling sessions back to back with other stressful commitments
- Use brief breathing exercises during the session if anxiety about the sensation builds
Clinics typically observe patients for a short period after the first few sessions to watch for lightheadedness before they leave. Most people drive themselves home and return to work or normal activities the same day, though your provider may advise precautions based on individual response.
Pro Tip: Track your side effects in a simple daily note, rating headache or scalp discomfort on a 1 to 10 scale. Patterns that show up in writing are far easier for your provider to act on than a vague “it’s been rough this week” at your next visit.
Does the TMS Device Type Change the Risk?
Standard repetitive TMS (rTMS), deep TMS using an H-coil, and newer theta-burst protocols all work on the same core principle, but they don’t produce identical side-effect profiles. Some patients report sharper scalp discomfort with certain H-coil designs because the coil covers a broader area of the head. That’s a comfort difference more than a safety one.
Theta-burst stimulation compresses a full session into a few minutes by delivering pulses in rapid bursts, and it’s gained popularity for that convenience. The tradeoff is less accumulated long-term safety data. A safety review by Rossi and colleagues flags patterned protocols like theta-burst as needing continued monitoring precisely because fewer years of real-world use exist to compare against standard rTMS.
Seizure-rate comparisons across device types remain limited by small sample sizes rather than any clear signal that one coil design is inherently riskier. If you’re weighing options, ask your provider directly which protocol they’re using and why they consider it appropriate for your situation.
What the Research Actually Shows About Frequency and Severity
A systematic review focused on older adults treated with rTMS found adverse events in 12.4% of patients, with headache and stimulation-site pain accounting for most of that figure.
| Data Source | Population | Reported Rate |
|---|---|---|
| Systematic review (older adults) | Adults treated with rTMS for depression | 12.4% any adverse event |
| Postmarketing seizure analysis | General TMS patient population | ~7 seizures per 100,000 sessions |
| Literature review of seizures | Pooled studies across age groups | Under 1% overall seizure risk |
Trial-based reviews capture every complaint, including a single headache on day one. Postmarketing seizure data track one specific, severe outcome across a much larger real-world population. Neither number is wrong. They’re just answering different questions, and a mild headache on your first visit says nothing about your seizure risk on your twentieth.
Warning Signs That Need Immediate Attention
Most TMS side effects resolve on their own or with simple adjustments, but a small set of symptoms warrants an urgent call to your care team rather than waiting until your next appointment.
- Seizure activity that lasts more than a few minutes or repeats within the same day
- New or worsening thoughts of self-harm at any point during treatment
- Hearing loss or ringing that persists well beyond the treatment session
- New visual disturbances, including blurred vision or flashing lights
Clinics typically respond with immediate observation and, when warranted, an emergency referral. Keeping a brief symptom log makes it far easier for your treatment team to tell the difference between an expected adjustment reaction and something that needs a faster response.
Weighing Rare Risks Against Real Benefit
TMS carries a strong safety record when clinics follow proper screening and dosing protocols, and that record holds up across the populations studied so far. TMS evaluations are available at multiple Florida locations, where clinicians walk patients through individual risk factors before treatment starts. The right decision is rarely one-size-fits-all. It comes from an honest conversation between you and a provider who knows your full medical picture.
— Kristofer
Getting Evaluated for TMS at Imindmental
If you’re weighing TMS against other options, the safest next step is a conversation with a clinician who can review your medical history before anything else. The team screens every patient for the risk factors covered above, including implants, seizure history, and medication interactions, before recommending a treatment plan tailored to your situation. Appointments are available across several Florida locations, and staff can verify insurance benefits ahead of your first visit so cost questions don’t linger. You can review the full TMS treatment program to see how evaluations work, or go straight to Imindmental’s TMS service page to request a consultation and start the screening process. If a psychiatric medication review makes sense alongside TMS, the psychiatry services team can coordinate that care in the same visit.
This article is general information, not a substitute for advice from a qualified doctor. Consult a qualified healthcare professional about your own circumstances before acting on anything here.
Sources
- PubMed record reporting clinical data on TMS-related seizures (2025/2026 postmarketing analysis)
- Transcranial magnetic stimulation – Mayo Clinic
- Consensus conference summary on TMS safety (IFCN)
- TMS-related seizures: literature review
