Transcranial Magnetic Stimulation (TMS) is a non-invasive, FDA-cleared treatment for conditions like Major Depressive Disorder (MDD).
It’s often considered when other treatments haven’t worked. Like any medical procedure, it comes with potential side effects, though most are mild and temporary.
It’s important for patients to understand these possibilities. This overview outlines the common, less common, and rare side effects linked to TMS.
Key Takeaways
- The most common TMS side effects are mild, temporary headaches and scalp discomfort at the treatment site.
- Serious adverse events, like a seizure, are extremely rare. They occur in fewer than 0.1% of patients under modern safety guidelines.
- Side effects usually become less frequent and less intense after the first few weeks of treatment as the patient’s body adjusts to the stimulation.
Most Common Side Effects of TMS
Most TMS side effects are mild and go away on their own. The most common issues come from the magnetic pulses on the scalp and muscles. These feelings are temporary, usually fading during or right after a session.
According to Mayo Clinic expert Liza Torborg, RN, TMS side effects are typically mild and directly tied to the stimulation itself:
“There can be some side effects as a result of transcranial magnetic stimulation, but usually they are mild. Common side effects include a headache, scalp discomfort and lightheadedness during treatment sessions. You may notice tingling, twitching or spasms in facial muscles, too.”
– Liza Torborg, RN, Mayo Clinic [1]
Common side effects include:
- Headache: This is the most common side effect, affecting about 20-30% of patients. These are usually tension headaches from the scalp muscles contracting. They can often be managed with common pain relievers and tend to happen less after the first week.
- Scalp Discomfort: Pain or discomfort at the treatment site is also common, affecting 10-20% of people. It’s often described as a tapping, knocking, or tingling feeling. The technician can usually reduce this by adjusting the coil’s position or lowering the stimulation a bit.
Duration of Typical TMS Side Effects
For most patients, TMS side effects are short-lived. The immediate physical sensations, like scalp discomfort or facial twitching, usually only last during the treatment session itself or fade within minutes to hours afterward. Broader effects, such as a headache or feeling lightheaded, typically persist for just a few hours after a session.
Key points about the timeline:
- Side effects often peak in intensity and frequency during the first week to ten days of treatment.
- A significant reduction, often by half or more, is commonly seen by the second or third week as the brain adjusts.
- It is unusual for side effects to continue after the main 4 to 6-week treatment phase ends.
Any symptoms that do persist should be discussed with your treating clinician to check for other possible causes unrelated to the TMS therapy.
Physical Side Effects During and After Sessions
The physical side effects of TMS are a direct result of how does TMS therapy work. The rapidly changing magnetic field creates a small electrical current in the brain tissue, which can also stimulate the nerves and muscles near the surface.
Common, short-lived physical effects include:
- Scalp Discomfort/Pain: A tapping or pressure sensation under the treatment coil.
- Facial Twitching or Tingling: Involuntary muscle contractions or tingling, often around the eye, jaw, or forehead, reported in 5-15% of sessions.
- Lightheadedness or Dizziness: A brief feeling, reported by 5-10% of patients, often when standing up right after a session.
- Auditory Effects: The magnetic coil makes a loud clicking sound. While there’s no risk of permanent hearing damage, the noise can be uncomfortable without proper ear protection, which is always provided.
These are considered normal responses to the stimulation. They rarely require any action beyond small adjustments to the treatment settings by the technician.
TMS-Associated Fatigue and Sleep Disturbances
Fatigue is a reported side effect for some patients, especially at the start of treatment. About 5-10% of people feel increased tiredness or drowsiness after their sessions.
This is likely related to the treatment’s effect on brain circuits that manage energy and alertness, as the brain adjusts to the stimulation.
Sleep disturbances, like changes in sleep patterns or mild insomnia, can also happen. These are often temporary and may be part of the broader brain changes the treatment aims to create, rather than a direct negative effect. For most, sleep patterns stabilize or even improve as their depressive symptoms lift.
Managing these effects is straightforward. Clinicians typically advise patients to stay hydrated, avoid scheduling intense activities right after a session, and practice good sleep habits. These symptoms usually lessen after the first few weeks of treatment.
Rare and Serious Risks of TMS
While TMS is generally safe, and widely recognized for its strong clinical safety profile as outlined in is TMS therapy safe, it does carry rare but serious risks that require careful screening.
The most significant risk is triggering a seizure. The chance of this is extremely low—less than 0.1% when modern safety rules are followed. This risk is reduced by screening for any history of seizures and carefully setting the treatment strength for each person.
Other serious risks are also very uncommon. These can include:
- Mania/Hypomania: Mainly a risk for those with bipolar disorder, occurring in less than 1% of cases.
- Psychiatric Hospitalization: Often related to the severity of the underlying condition, not directly from TMS.
- Prolonged Speech Difficulty: Isolated cases exist but are extraordinarily rare and usually temporary.
These risks are why TMS must be done under a qualified psychiatrist’s supervision in a clinical setting prepared for emergencies, even though they are very unlikely.
TMS and the Risk of Mania or Mood Changes
TMS can, in rare cases, trigger a manic episode. This is a considered risk, especially for people with bipolar disorder. The overall chance is low, happening in less than 1% of patients. It’s thought to occur from overstimulating the brain’s mood circuits.
Because of this risk, a detailed psychiatric evaluation is essential before starting TMS. This screening looks for any personal or family history of bipolar disorder. At TMS of Tennessee, we review your history carefully, including past episodes of unusually high mood, energy, or needing very little sleep.
If you have bipolar disorder and are a candidate for TMS, the treatment is usually given while you’re also taking a mood stabilizer and under close watch.
Any new symptoms of elevated mood or impulsivity are addressed right away, which may mean pausing treatment or adjusting your medications.
Comparison of TMS Side Effects to Other Treatments
When evaluating treatment options for Major Depressive Disorder, the side effect profile is a major differentiator, especially when comparing different types of TMS therapy. TMS offers a distinct advantage in its lack of systemic pharmacological effects.
Harvard Health Publishing contributor Michael Craig Miller, M.D. explains the typical side effect experience with TMS compared to systemic treatments:
“The most common side effects of the treatment are a mild to moderate headache or scalp pain below where the device was positioned. Since the magnetic pulses can be loud, some people experience ringing in the ears from the noise of the treatment. Wearing earplugs or earphones helps.”
– Michael Craig Miller, M.D., Harvard Health Publishing [2]
| Treatment Modality | Common Side Effects | Systemic/Cognitive Impact |
| SSRI/SNRI Medications | Nausea, weight change, sexual dysfunction, insomnia/somnolence. | Widespread systemic effects due to whole-body bioavailability. |
| Transcranial Magnetic Stimulation (TMS) | Headache, scalp discomfort, facial twitching (site-specific). | No systemic drug interactions; no negative impact on cognition or memory. |
| Electroconvulsive Therapy (ECT) | Short-term memory loss, confusion, muscle aches, cardiovascular strain. | Requires anesthesia; associated with transient cognitive side effects. |
The localized nature of TMS side effects allows over 85-90% of patients to complete a full treatment course without discontinuation due to intolerance.
Furthermore, patients can drive themselves to and from treatment and immediately resume normal activities, which is not always the case with other interventions.
Contraindications for TMS Treatment
TMS is not suitable for everyone due to specific safety concerns. These are mainly related to having certain metallic objects in the head or having particular neurological conditions.
Having implanted metallic devices or objects in or near the head is an absolute reason not to have TMS. This includes:
- Aneurysm clips or coils
- Stents in the neck or brain
- Implanted electrodes (like deep brain or vagus nerve stimulators)
- Cochlear implants
- Metal plates or shrapnel in the skull or eye area
- Implantable cardioverter-defibrillators (ICDs) – this is a relative concern due to a theoretical risk.
A history of seizures or a condition that greatly raises your seizure risk is a main reason not to have TMS. Also, TMS is not FDA-approved for children or during pregnancy. In very specific cases, it might be considered after a full discussion of the possible risks and benefits.
When to Contact a Clinician About Side Effects
Clear communication with your treatment team is essential for safe TMS. You should report any side effects to your technician and supervising doctor. While most are minor, certain symptoms need prompt medical attention.
You should contact your clinician right away if you experience:
- Symptoms that could indicate a seizure, like involuntary jerking, loss of consciousness, or confusion.
- A severe, persistent headache that doesn’t get better with typical pain relievers.
- New or worsening suicidal thoughts.
- Signs of mania, such as a drastically reduced need for sleep, racing thoughts, or impulsive, high-risk behavior.
- Any severe, prolonged, or unusual neurological symptom that is different from the brief sensations felt during treatment.
At TMS of Tennessee, patient safety is our top priority. Our clinical team is trained to assess and manage any issues that arise, and we continuously adjust treatment settings to ensure the best balance of comfort and effectiveness for each person.
FAQ
What are the most common side effects of Transcranial Magnetic Stimulation?
The most common side effects of Transcranial Magnetic Stimulation include scalp discomfort, tingling sensation, and application site pain during magnetic stimulation.
Some people also feel jaw pain or muscle twitching as magnetic pulses activate nerve cells in the prefrontal cortex.
These effects usually fade within minutes or hours after treatment and rarely affect long-term brain activity or overall mental health.
Can TMS therapy cause serious adverse events like seizures?
Serious adverse events are rare, but seizure risk exists, especially for people with seizure disorder, brain tumors, prior head injury, or metal plates near brain tissue.
Providers reduce this risk by using proper motor threshold determination, safe stimulation parameters, and trained staff.
Clinics also screen for cerebrovascular disease and seizure risk factors before starting repetitive transcranial magnetic stimulation or Deep Transcranial Magnetic Stimulation.
How does coil placement affect side effects during repetitive TMS?
Coil placements over the dorsolateral prefrontal cortex directly affect both comfort and results. Incorrect positioning of the electromagnetic coil can increase site pain, facial nerve twitching, or auditory side effects.
Accurate motor hotspot mapping, dosage selection, and careful motor threshold testing help protect neural circuits while supporting neural plasticity and healthy cortical excitation.
Who should avoid TMS because of medical implants or conditions?
People with cochlear implant devices, implantable cardioverter defibrillators, metallurgical implants, or brain lesions may not qualify for TMS therapy. Strong magnetic fields can interfere with these devices.
Providers also screen for bipolar disorder, substance use disorders, psychiatric emergencies, and severe depression history to confirm a safe safety profile before treatment begins.
Do TMS side effects differ for depression, OCD, or anxiety disorders?
Side effects remain similar across Major Depressive Disorder, obsessive-compulsive disorder, post-traumatic stress disorder, and anxiety disorders. Scalp discomfort and stimulation site pain occur most often.
Response rates vary based on targeted brain regions and neural activity patterns. Some patients report mild headaches or fatigue, while remission rates improve when treatment matches each person’s brain’s prefrontal cortex activity.
Clinical Considerations and Final Guidance
Transcranial Magnetic Stimulation is a major advance for treating medication-resistant depression and OCD. Its side effects are generally favorable, with most being mild and temporary. Serious risks are minimized through careful screening and protocols.
The decision to pursue TMS should be made with a qualified psychiatrist. For the right candidate, the benefit of achieving remission often outweighs the risk of short-term side effects.
For Tennesseans without relief from standard antidepressants, TMS of Tennessee offers FDA-cleared NeuroStar therapy. To see if you’re a candidate, consult your psychiatrist or contact our clinic.
References
- https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-q-and-a-transcranial-magnetic-stimulation-may-ease-depression-symptoms/
- https://www.health.harvard.edu/blog/magnetic-stimulation-a-new-approach-to-treating-depression-201207265064
