TMS is a non-invasive depression treatment whose common, usually temporary effects include scalp discomfort and headaches, requiring clinical screening and monitoring.
TMS Side Effects and Safety: A California Patient Guide
Transcranial magnetic stimulation (TMS) is a non-invasive treatment that uses magnetic pulses to stimulate targeted areas of the brain. It is most commonly considered for major depressive disorder, particularly when other treatments have not provided enough relief or have caused difficult side effects.
TMS was cleared by the US Food and Drug Administration (FDA) for major depressive disorder in 2008, and for depression with comorbid anxiety in 2021. It does not involve surgery, electrical current passing through the body, or a general anaesthetic. People remain awake during sessions and can usually return to their usual activities afterwards.
Like any medical treatment, TMS has potential side effects and safety considerations. A proper assessment by a qualified clinician is important before starting treatment.
The most common TMS side effects
The most frequently reported side effects of TMS are scalp discomfort and headache. These are usually mild to moderate, tend to occur during or shortly after sessions, and often improve as treatment continues.
During treatment, you may feel tapping, knocking or tightening sensations on the scalp. The treatment coil sits against the head and produces repeated magnetic pulses. Some people find the sensation uncomfortable at first, particularly at higher treatment intensities.
Common effects can include:
- Scalp tenderness or sensitivity where the coil is placed
- A mild headache during or after a session
- Facial muscle twitching near the treatment area
- Brief discomfort from the sound of the machine
- Tiredness after an appointment
A TMS clinician can often make practical adjustments if treatment feels too uncomfortable. For example, they may check the coil position, review the intensity setting or allow a short pause. It is helpful to say something during the session rather than trying to tolerate pain in silence.
Headaches may respond to rest, hydration or an over-the-counter pain medicine if it is appropriate for you. However, ask your clinician or usual prescriber before taking a new medicine, especially if you have other health conditions or take regular medication.
How long do side effects last?
For many people, discomfort is temporary and becomes easier to manage after the first part of a treatment course. A standard course of TMS is often delivered on weekdays over roughly six to nine weeks, with about 36 sessions. Your own plan may differ depending on the type of TMS offered and your clinical needs.
Side effects should be discussed at every stage, not only at the initial consultation. Tell the treatment team if a headache is severe, lasts longer than expected, changes in character, or comes with other symptoms such as confusion, weakness, vision changes or vomiting. These symptoms may not necessarily be caused by TMS, but they deserve medical advice.
The rare risk of seizure
Seizure is a recognised but rare risk of TMS. Clinics use screening procedures, treatment protocols and monitoring to reduce this risk. Your clinician should explain the safety process, answer questions about your own circumstances and advise you about anything that could affect seizure risk.
The risk assessment may include your medical history, past seizures, sleep, alcohol or substance use, and current medicines. Some medicines can affect seizure threshold. This does not always mean TMS cannot go ahead, but it may affect how the clinician plans or monitors treatment.
Tell the clinic promptly if there are changes during a course of treatment, such as:
- A new medication, dose change or missed doses
- Heavy alcohol use, alcohol withdrawal or recreational drug use
- Significant sleep deprivation
- A recent head injury
- A new neurological symptom or diagnosis
- A seizure or fainting episode
If a seizure occurs during treatment, the clinic should have procedures in place to respond and arrange appropriate medical care. Ask how the clinic handles urgent events before you begin.
Metal implants and other contraindications
TMS uses a strong magnetic field close to the head. For this reason, certain implanted metal or electronic devices in or near the head may make TMS unsuitable or require specialist review.
It is particularly important to tell the clinician about any implanted device, metal fragment or previous surgery involving the head, face, neck or brain. Examples may include some aneurysm clips, implanted stimulators, cochlear implants, metal plates or other devices that could be affected by a magnetic field.
Do not assume that an implant is safe simply because it has been in place for years. The clinic may need details about its make, model and location, and may ask for records from a surgeon or other specialist.
Dental fillings, crowns and braces are often not a barrier to TMS, but you should still mention them. The treatment team can decide whether any further checks are needed.
Health conditions to discuss before treatment
A TMS assessment should cover more than depression symptoms. It should include your wider physical and mental health history, previous treatments and current support.
Tell the clinician if you have, or may have:
- A history of seizures, epilepsy or unexplained blackouts
- A brain injury, stroke, brain tumour or neurological condition
- Frequent severe headaches or migraine
- Bipolar disorder, mania or hypomania
- Psychosis, hallucinations or severe agitation
- Substance use concerns
- Hearing difficulties or sensitivity to noise
- Pregnancy, plans for pregnancy or breastfeeding
- Any implanted medical device or retained metal fragment
These issues do not automatically rule out TMS. They help the clinician decide whether TMS is appropriate, whether another treatment should be considered, or whether additional precautions are needed.
For people with bipolar disorder, it is especially important to discuss any history of elevated mood, reduced need for sleep, impulsive behaviour or unusually high energy. Depression treatment can sometimes be associated with changes in mood state, so clinicians need a full picture before making recommendations.
Medicines, alcohol and day-to-day safety
Bring an up-to-date list of all prescription medicines, non-prescription medicines, vitamins and supplements to your consultation. Include medicines prescribed by other clinicians. Do not stop or alter medication on your own in preparation for TMS.
Be open about alcohol, cannabis and other substance use. This information is used for safety planning, not judgement. Changes in alcohol intake, missed medication and poor sleep can all be relevant during a treatment course.
TMS does not usually require sedation. Many people are able to travel to and from appointments independently, but your clinician can advise based on your health, medication and how you feel after sessions. If you feel unwell, dizzy, unusually tired or concerned about a symptom, ask before driving.
Hearing protection is generally used during sessions because the TMS device produces a repetitive clicking sound. Tell the staff if the ear protection is uncomfortable or if you have existing hearing concerns.
Questions to ask a California TMS clinic
Before choosing a provider, ask who will assess you, who delivers treatment and how side effects are monitored. You may also want to ask what happens if you miss an appointment, have a medication change or develop new symptoms during the course.
Useful questions include:
- Am I medically suitable for TMS?
- Do any of my implants, health conditions or medicines need further review?
- What side effects should I expect, and who do I contact after a session?
- How does the clinic manage an urgent safety concern?
- How will progress and changes in symptoms be reviewed?
- Will you coordinate with my psychiatrist, primary care clinician or therapist?
California has a wide range of TMS providers, and practical factors such as travel, scheduling and insurance can matter when treatment involves regular weekday visits. TMS Therapy California currently lists 382 published clinics, including listings in Los Angeles, San Diego, Carlsbad, Sacramento, San Jose, Long Beach, Aliso Viejo, Chula Vista, Simi Valley, Roseville, Irvine and Davis.
Getting help in California
Use the TMS Therapy California clinic listings to find providers, the insurance guide to review commonly seen plans including Blue Shield of California, Anthem Blue Cross of California, Kaiser Permanente, Medi-Cal and Medicare, and the contact page for further help navigating the directory.
This is educational information, not medical advice.
This page is informational and is not medical advice.