TMS Side Effects & Safety: What You Need to Know
Comprehensive guide to TMS safety: common side effects, rare risks, who should avoid TMS, and what to report to your doctor.
Clinically Reviewed: Board-Certified Psychiatrist |Next Review: May 2025
Key Takeaways
- TMS has an excellent safety profile with millions of treatments delivered worldwide
- Most side effects are mild and temporary: scalp discomfort (30-40%) and headache (20-30%)
- Seizure risk is extremely low (less than 0.1%, approximately 1 in 30,000 sessions)
- Thorough safety screening identifies people who should not use TMS
- Over 20 years of research and clinical use support TMS long-term safety
TMS Safety Overview
TMS has been used clinically for over 20 years, with millions of treatment sessions delivered worldwide. It has an excellent safety record and is generally well-tolerated.
The most common side effects are mild and temporary. Serious adverse events are rare when proper screening and protocols are followed.
Common Side Effects (Usually Mild & Temporary)
1. Scalp Discomfort or Tingling
Frequency: 30-40% of peopleSeverity: Mild to moderate
What it feels like:
Tapping, tingling, or mild stinging sensation on the scalp during magnetic pulses.
Management:
- Usually lessens significantly after first week
- Technician can adjust coil position or intensity
- Taking acetaminophen/ibuprofen before session may help
- Sensation typically becomes tolerable quickly
2. Headache
Frequency: 20-30% of peopleSeverity: Mild
What it feels like:
Tension-type headache after sessions, usually resolves within hours.
Management:
- Over-the-counter pain relievers (acetaminophen, ibuprofen)
- Hydration before and after sessions
- Usually improves after first week of treatment
- Rarely severe enough to discontinue treatment
3. Facial Twitching During Treatment
Frequency: Most peopleSeverity: Mild, temporary
What it feels like:
Brief muscle contraction in face/jaw during each magnetic pulse. Stops immediately when pulses stop.
Management:
- Normal and expected—shows the magnetic field is working
- Can be reduced by adjusting coil position
- Not harmful; purely a stimulation effect
4. Lightheadedness or Dizziness
Frequency: Less than 10%Severity: Mild
Management:
- Usually related to sitting still for 20-30 minutes
- Stand up slowly after treatment
- Stay hydrated
- Rare to interfere with daily activities
Rare but Serious Risks
Serious Side Effects (Very Rare)
Seizure (Less than 0.1% risk)
Extremely rare—approximately 1 in 30,000 sessions. Risk factors include personal or family history of seizures, brain injury, certain medications, or alcohol withdrawal. We screen carefully to minimize this risk.
If a seizure occurs, it is managed medically and TMS is typically discontinued.
Hearing Changes (Very Rare)
Can occur if earplugs are not worn consistently. Always wear provided hearing protection during sessions.
Mania or Hypomania (Rare in Bipolar Disorder)
In people with bipolar disorder, TMS may trigger mood elevation. We monitor closely and may adjust mood stabilizers during treatment.
Safety Screening: What We Check Before Treatment
Before starting TMS, you'll complete a comprehensive safety evaluation:
- Medical history: Seizure disorders, brain injury, neurological conditions
- Medications: Drugs that lower seizure threshold (some antipsychotics, bupropion at high doses)
- Metal screening: Any metal implants or devices in/near your head
- Cardiac devices: Pacemakers, implanted defibrillators (usually not contraindications but require evaluation)
- Pregnancy status: Confirmed not pregnant (TMS avoided during pregnancy)
- Substance use: Alcohol or drug use that could affect seizure risk
Absolute Contraindications: Who Should NOT Use TMS
TMS is NOT Safe If You Have:
- Metallic implants in or near head: Cochlear implants, aneurysm clips, brain stimulators, metallic foreign bodies
- Certain medical devices: Deep brain stimulators, vagus nerve stimulators near head
- Metallic ink tattoos on scalp: Face/neck tattoos are okay, but scalp tattoos with metallic ink can heat up
Note: Dental fillings, braces, and metal elsewhere in body (hips, knees, etc.) are typically NOT contraindications. Always disclose all metal to your doctor.
Monitoring During Treatment
Throughout your TMS course, we monitor for safety and effectiveness:
- Before each session: Ask about new symptoms, medication changes, or concerns
- During sessions: Monitor for comfort and any unusual reactions
- Weekly assessments: Track mood, side effects, and response to treatment
- Ongoing communication: Coordinate with your psychiatrist about medications and progress
When to Call Your Doctor
Contact Your Doctor If You Experience:
- • Severe or worsening headaches that don't respond to over-the-counter pain relief
- • Unusual mood changes, agitation, or new suicidal thoughts
- • Twitching that continues after treatment ends
- • Hearing changes, ringing in ears, or muffled hearing
- • Signs of mania: decreased need for sleep, racing thoughts, impulsive behavior
- • Seizure-like activity: convulsions, loss of consciousness, confusion
- • Skin irritation or burns on scalp
- • Any other concerning symptoms
Our contact: (405) 934-1681
Long-Term Safety Data
Extensive research over two decades supports TMS safety:
- No cognitive effects: TMS does not cause memory loss or cognitive decline
- No brain tissue damage: Magnetic fields do not harm neurons
- No systemic toxicity: Unlike medications, TMS doesn't affect liver, kidneys, or other organs
- Reversible: If stopped, no lingering physical effects (though mood symptoms may return)
Long-term follow-up studies (5-10 years) have not identified concerning late effects or complications from TMS treatment.
Frequently Asked Questions
Will TMS hurt?
TMS is not typically described as painful. Most people feel a tapping sensation on their scalp and hear clicking sounds. Some experience mild scalp discomfort, especially during the first few sessions, which usually lessens as your body adjusts. We can adjust settings to improve comfort.
How common are TMS side effects?
Common side effects include scalp discomfort (30-40% of people) and mild headache (20-30%). These are usually mild, temporary, and most common in the first week of treatment. Serious side effects are very rare.
Can TMS cause brain damage?
No. TMS uses magnetic fields similar to an MRI and does not cause brain damage. Extensive research over 20+ years shows TMS does not harm brain tissue. In fact, TMS may promote healthy brain changes (neuroplasticity) that support mood improvement.
Is TMS safe during pregnancy?
TMS is generally avoided during pregnancy due to limited safety data, not because of known harm. While magnetic fields at TMS levels haven't shown fetal harm in studies, the cautious approach is to wait until after pregnancy. If you're pregnant or planning pregnancy, discuss timing with your doctor.
Can TMS cause seizures?
Seizures are extremely rare with TMS—less than 0.1% risk (approximately 1 in 30,000 sessions). The risk is similar to the spontaneous seizure risk in the general population. We screen for seizure risk factors (history of seizures, brain lesions, certain medications) before treatment.
What about hearing loss from TMS?
Hearing loss is very rare and preventable. The clicking sound during TMS can be loud, which is why we provide earplugs for every session. As long as you wear earplugs as instructed, hearing damage is not expected.
Can TMS make depression worse?
This is very uncommon. Some people may feel emotionally sensitive or have mood fluctuations during treatment, which can be part of the brain adjustment process. If you experience worsening depression, new suicidal thoughts, or unusual mood changes, contact your doctor immediately.
Is TMS safer than medication?
TMS and medications have different safety profiles. TMS avoids systemic side effects like nausea, weight changes, or sexual dysfunction that can occur with medications. However, TMS requires clinic visits and has rare risks like seizures. Neither is universally 'safer'—it depends on your individual health and circumstances.
Can I do TMS if I have metal in my body?
It depends on the type and location. Metal in or near your head (cochlear implants, aneurysm clips, deep brain stimulators) is typically a contraindication. Metal elsewhere in your body (knee replacement, dental fillings) is usually fine. Provide a complete list of any metal implants or medical devices during screening.
Are there long-term effects of TMS?
Long-term follow-up studies (5-10 years) have not identified concerning late effects. TMS does not appear to cause cognitive decline, memory problems, or other long-term complications. The main 'long-term effect' we aim for is sustained improvement in mood.
Plain-Language References
- 1. Rossi S, et al. (2021). "Safety and recommendations for TMS use in healthy subjects and patient populations." Clinical Neurophysiology 132(1):269-306.
- 2. Loo CK, et al. (2008). "A review of the safety of repetitive transcranial magnetic stimulation as a clinical treatment for depression." International Journal of Neuropsychopharmacology 11(1):131-147.
- 3. Perera T, et al. (2016). "The Clinical TMS Society Consensus Review and Treatment Recommendations for TMS Therapy for Major Depressive Disorder." Brain Stimulation 9(3):336-346.