What to Expect During Your First TMS Therapy Session

The first session of transcranial magnetic stimulation is longer and more involved than subsequent ones because it includes a one-time procedure called motor-threshold mapping — the calibration step that sets the dose used for every session that follows. Patients and families consistently report that knowing what to expect, in concrete terms, reduces day-of anxiety more than any single piece of reassurance. This article walks through the full first visit: paperwork, mapping, the treatment itself, what you will feel, what you will hear, and what a normal next 24 hours looks like.

Before you arrive: what to bring and how to prepare

The first session typically takes 60 to 90 minutes total — longer than subsequent sessions, which run roughly 20 to 40 minutes for the standard 10 Hz protocol or as short as ~3 minutes of active stimulation for intermittent theta burst (iTBS). Plan accordingly. Practical preparation:

• Wear comfortable clothing that lets you sit upright in a treatment chair for 45 minutes or more. There is no gown change; nothing is placed under your clothing.
• Eat a normal meal beforehand. TMS is not performed under sedation, and there is no fasting requirement, but you will be more comfortable if you are not hungry.
• Take your regular medications unless your psychiatrist has specifically instructed otherwise. TMS does not require you to stop antidepressants or other psychiatric medications — and stopping them on your own is not recommended.
• Remove ferromagnetic items from your head and neck before the session — jewelry, hairpins, hearing aids. The treatment coil's magnetic field can interact with these.
• Bring a list of current medications and your insurance card if it has not already been documented at intake.
• No driver is required. TMS does not affect alertness or cognition, and most patients drive themselves to and from sessions.

If you have any history of seizure, head injury with loss of consciousness, or ferromagnetic implants in the head (cochlear implants, deep-brain stimulators, aneurysm clips, intracranial electrodes, retained metal fragments), confirm these were disclosed at the candidacy evaluation. Standard dental work — amalgam fillings, single titanium implants, routine bridgework — is not a contraindication; the treatment team will confirm the specifics at the first session.¹

Step 1: Motor-threshold mapping (one-time, ~20 minutes)

The clinical goal of mapping is to determine your individual motor threshold (MT) — the lowest level of stimulator output that reliably produces a visible muscle twitch in your hand when the coil is placed over the corresponding region of motor cortex. The MT is used to set treatment intensity, typically at 120% of MT. Because cortical excitability varies meaningfully from person to person, this calibration is done individually rather than using a fixed dose.

In practice, mapping looks like this:

1. You are seated in the treatment chair, head supported.
2. The technician places the coil over the area of motor cortex that controls hand muscles, on the side opposite to the target hand.
3. The system delivers single magnetic pulses at gradually changing intensity.
4. The technician observes your hand for a visible thumb or finger twitch. (You will feel a tap on your scalp and may feel a small muscle contraction; the twitch itself is brief and painless.)
5. The intensity producing the twitch in at least 5 of 10 pulses is recorded as your motor threshold.

Once MT is recorded, the coil is repositioned forward and laterally to the left dorsolateral prefrontal cortex (DLPFC) — the standard depression target.¹ In the original FDA-cleared NeuroStar protocol, this is done with a fixed-distance scalp rule (the "5.5 cm rule") from the motor site. The Beam F3 scalp-mapping method and MRI-guided neuronavigation are increasingly used clinically — neuronavigation is built into FDA-cleared accelerated protocols such as Stanford's SAINT.

Motor-threshold mapping is performed once, at the first session, and re-checked periodically through the course if needed. The treatment dose remains stable thereafter.

Step 2: The treatment itself (~20–40 minutes)

After mapping, the first treatment is delivered. The two FDA-cleared protocols in routine use are:

• 10 Hz repetitive TMS (rTMS) — pulses delivered at 10 Hz in 4-second trains with 26-second rest intervals, totaling approximately 3,000 pulses across roughly 37 minutes.
• Intermittent theta burst stimulation (iTBS) — patterned bursts delivering 600 pulses in approximately 3 minutes.

Both protocols are FDA-cleared for depression, and both qualify for insurance coverage. Your psychiatrist selects the protocol based on tolerability, schedule, and prior response history. Once treatment begins, you may:

• Read, watch a tablet, or listen to audio (ear protection is provided)
• Talk with the technician between trains
• Stop the session at any time if you are uncomfortable

Sedation is not used. You remain fully awake and alert.

What you will feel and hear

The two sensations most patients describe at the first session are the scalp sensation and the device sound. Both are normal and both are well-characterized.

• Scalp sensation. Each pulse feels like a sharp tap or knock on the scalp directly under the coil. Some patients describe it as a woodpecker tapping; others, as a flicking sensation. The trains pause every few seconds, so the tapping is rhythmic, not continuous. Most patients report the sensation is most noticeable in the first one to five sessions and diminishes as the scalp accommodates.²
• Facial-muscle contraction. Because the DLPFC sits near nerves that supply jaw and forehead muscles, you may feel a small twitch of the cheek, temple, or jaw with each pulse. This is normal and not painful — it stops the moment the train stops.
• Device sound. The coil produces a sharp clicking sound (roughly 100 dB at the coil, attenuated by foam earplugs). Hearing protection is provided and required.
• No internal sensation. You will not feel anything inside your head. The pulse stimulates a focal region of cortex but does not produce sensations of pressure, heat, light, or movement beyond the scalp surface.

In the original FDA pivotal trial and in subsequent open-label studies, scalp discomfort and headache were the most common adverse events, both typically mild and decreasing in frequency through the first one to two weeks of treatment.²

After the session: what's normal in the next 24 hours

Most patients walk out of the first session and drive themselves home, back to work, or to their next appointment. Concretely:

• Headache. A mild-to-moderate headache, typically frontal and resolving within a few hours, is the most common post-session experience early in the course. Over-the-counter acetaminophen or ibuprofen is usually sufficient; check with your psychiatrist regarding any medication you are not already taking.
• Scalp tenderness. Mild tenderness over the treatment site for several hours is normal.
• Fatigue. A small percentage of patients report mild fatigue after the first few sessions. It is typically transient.
• Mood. Patients should not expect a mood change after a single session. Therapeutic response builds over weeks of cumulative treatment, not immediately.

Serious adverse events are rare when established safety guidelines are followed. The most clinically significant rare event is seizure, estimated at fewer than 1 in 60,000 sessions in contemporary pooled data with figure-8 coils and standard protocols.³⁴ Standard pre-treatment screening is designed to identify the small subset of patients for whom seizure risk is meaningfully elevated.

When to call the clinic between sessions:

• Headache that does not respond to over-the-counter medication
• Persistent scalp pain at the treatment site
• New neurological symptoms (vision change, weakness, confusion)
• Worsening mood or new suicidal thoughts (this is a safety call, not an inconvenience)

What to expect across the full course

A standard course is approximately 36 sessions over six to nine weeks — typically five sessions per week for the first six weeks, followed by a taper. Response is gradual and cumulative. Most clinical-trial cohorts show measurable improvement starting around weeks two to four, with full response typically assessed at the end of the course.²

PHQ-9 or other rating-scale scores are tracked through the course so progress can be measured objectively rather than estimated by recall.

Key takeaways

• The first TMS session takes 60 to 90 minutes — longer than later sessions — because it includes motor-threshold mapping, a one-time calibration step.
• The treatment itself is delivered awake and unsedated; you can read, listen to audio, or talk during the session.
• Expect a tapping sensation on the scalp, a clicking sound (ear protection provided), and possibly a small facial-muscle twitch — all normal and well-characterized.
• Mild headache and scalp tenderness are the most common after-effects in the first one to two weeks; both typically diminish with continued treatment.
• A full course is approximately 36 sessions over six to nine weeks; therapeutic response is cumulative, not immediate.

For patients in Anaheim, Orange County, and the broader 30-mile radius beginning TMS therapy, the first-session walkthrough above is what to expect at our clinic. If you have not yet confirmed coverage, the insurance verification form takes about two minutes and gives our team what we need to confirm benefits before your first visit.

Sources / Further reading