If you or someone you love is considering transcranial magnetic stimulation for depression or another mental health condition, understanding the full picture of TMS side effects is one of the most important steps you can take before beginning treatment. TMS has gained significant traction as a non-invasive, FDA-approved option for people who haven’t found relief through medication or therapy — but like any medical treatment, it comes with a side effect profile worth understanding clearly and honestly.
This guide covers what the clinical evidence actually says about TMS side effects, how common they are, which ones are serious, and what you can realistically expect throughout your treatment course.
What Is TMS and How Does It Work?
Transcranial magnetic stimulation is a non-invasive brain stimulation technique that uses pulsed magnetic fields to stimulate specific nerve cells in the brain. It is most commonly used to target the dorsolateral prefrontal cortex (DLPFC), a region involved in mood regulation.
According to the National Institute of Mental Health (NIMH), TMS is FDA-approved for treating major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and smoking cessation. As of 2024, it has also received FDA approval for adolescents aged 15 and older with MDD.
A standard course typically involves five sessions per week over four to eight weeks, with each session lasting 20 to 40 minutes. Patients remain fully awake throughout — no sedation or anesthesia is required.
Common TMS Side Effects: What Most Patients Experience
Headaches
Headaches are the most frequently reported side effect of TMS therapy. According to a National Institute of Mental Health safety presentation by Dr. Sarah Lisanby, approximately 36% of patients in the FDA pivotal trial experienced application site pain, while around 11% reported scalp discomfort. These headaches are typically caused by the magnetic field stimulating scalp muscles, producing a muscle tension-type sensation.
The good news: headaches are usually mild to moderate in intensity and tend to resolve within an hour after the session. Most patients find they decrease significantly — often by more than 70% — by the second week of treatment as the scalp and surrounding nerves adapt.
Over-the-counter pain relief (ibuprofen, acetaminophen) is generally effective, but patients should always consult their treatment team before taking any medication during a TMS course.
Scalp Discomfort and Tingling
Scalp discomfort at the site where the magnetic coil is placed is the second most commonly reported side effect. It typically manifests as a tapping, knocking, or tingling sensation during each magnetic pulse. According to Washington Behavioral Medicine Associates, scalp discomfort affects roughly 25% of patients during initial sessions, but generally resolves within an hour and diminishes substantially after the first week.
Patients are encouraged to communicate with their technician if discomfort is significant — stimulation parameters can often be adjusted to improve tolerability without compromising treatment effectiveness.
Facial Muscle Twitching
During TMS sessions, magnetic pulses can stimulate nearby nerves and cause involuntary, brief muscle contractions in the jaw or face. This is a normal physiological response and typically stops as soon as the stimulation ends. It does not indicate a harmful event and is not considered a serious adverse effect.
Lightheadedness and Mild Fatigue
Some patients report feeling lightheaded during treatment sessions, particularly early on. Post-treatment fatigue — a sense of mental tiredness — can also occur. This is thought to result from the brain’s increased activity during stimulation, somewhat like the tiredness felt after an intense cognitive workout. These effects are typically mild and resolve quickly after each session.
Serious TMS Side Effects: Rare but Important to Understand
Seizures
The most serious potential risk associated with TMS is seizure induction. However, it is important to put this risk in proper perspective.
According to data cited by the NIMH’s TMS safety review, the FDA pivotal trial involving approximately 300 patients recorded no seizures. Larger post-market surveys have estimated the seizure rate at roughly 0.31 per 10,000 individual sessions — meaning seizures are exceptionally rare in the broader patient population.
To put this in context, research published in Brain Stimulation (Taylor et al., 2021, surveying over half a million treatment sessions) confirmed that the seizure risk from TMS is comparable to — and in some cases lower than — the seizure risk associated with many commonly prescribed psychiatric medications.
Seizures during TMS, when they do occur, are typically self-limiting and stop when stimulation ends. Patients with a personal history of epilepsy or seizure disorders, or those taking medications known to lower the seizure threshold, require specialized screening before TMS is considered appropriate.
Hearing Discomfort
TMS machines produce a repetitive clicking sound that can exceed 100 decibels — similar in volume to an MRI machine. Without proper protection, this noise poses a theoretical risk for transient hearing threshold shifts or tinnitus (ringing in the ears). To prevent this, FDA safety guidelines mandate the use of medical-grade earplugs during every session, and reputable clinics universally provide them.
Treatment-Emergent Hypomania or Mania
In rare instances, TMS has been associated with the emergence of hypomanic or manic symptoms. According to a review by Gupta & Adnan (2018), this risk appears most significant in patients with an underlying bipolar disorder but has occasionally been reported in those being treated for unipolar depression. This is why a thorough psychiatric evaluation — including assessment for bipolar spectrum conditions — is essential before initiating TMS therapy.
What TMS Does NOT Cause
One of the most clinically significant points about TMS is what it doesn’t do, especially compared to alternatives:
- No cognitive impairment or memory loss: According to Mayo Clinic, unlike electroconvulsive therapy (ECT), TMS has not been associated with memory loss or confusion. Research has found that cognitive function remains stable or may actually improve over the course of treatment, consistent with improvements in depressive symptoms.
- No systemic side effects: Because TMS targets a specific brain region rather than affecting the entire body through the bloodstream, it does not cause the weight gain, sexual dysfunction, or systemic fatigue commonly associated with antidepressant medications.
- No sedation required: Patients drive themselves to appointments and resume their normal daily activities immediately after each session.
Who Should Be Cautious About TMS?
TMS is not appropriate for everyone. People with the following factors should discuss their situation carefully with a qualified physician before proceeding:
- Metal implants in or near the head: Cochlear implants, pacemakers, deep brain stimulators, or metallic objects in the skull can interact with TMS’s magnetic field. Dental fillings and most metal implants located away from the head are generally not a concern.
- Personal history of seizures or epilepsy: These patients require specialized neurology consultation and careful risk assessment before TMS is considered.
- Bipolar disorder: The risk of treatment-emergent mania requires careful psychiatric monitoring throughout the course of treatment.
- Pregnancy: There is insufficient safety data for TMS during pregnancy; providers should weigh risks and benefits carefully on a case-by-case basis.
What the Clinical Evidence Says Overall
The overall body of evidence strongly supports TMS as a safe and well-tolerated treatment. In both the industry-sponsored FDA pivotal trial and the independent NIMH-sponsored randomized controlled trial, there were no seizures, deaths, or suicides, and fewer than 5.5% of patients discontinued treatment due to adverse effects.
A 2024 consensus review backed by major institutions — including the National Network of Depression Centers and the Clinical TMS Society — confirmed that TMS does not cause the systemic side effects such as weight gain or fatigue that are associated with medication-based treatments.
A scoping review published in the Journal of Clinical Medicine (2025) found that adverse effects from TMS were rare, mild, and transient, supporting the treatment’s safety profile even in older adult populations.
Tips for Managing Side Effects During Treatment
- Stay hydrated before and after sessions, as dehydration can worsen headaches
- Take OTC pain relief proactively if your provider approves, particularly before early sessions
- Always wear earplugs provided by your clinic — do not skip this step
- Report any side effects to your treatment team promptly; parameters can often be adjusted
- Track your symptoms in a simple journal to share with your provider at each visit
- Continue your medications and therapy unless your provider instructs otherwise
When to Seek Immediate Medical Attention
While serious adverse events are rare, patients should seek immediate medical care if they experience:
- A seizure or seizure-like activity during or after a session
- Severe or worsening headache with neurological symptoms (vision changes, weakness, confusion)
- A headache significantly different from previous post-TMS headaches
- Sudden changes in mood toward euphoria, decreased need for sleep, or impulsive behavior
Final Thoughts
For the majority of patients, TMS side effects are mild, temporary, and manageable — and they typically lessen as treatment progresses. The most common complaints (scalp discomfort and headache) resolve quickly and rarely cause patients to discontinue treatment. Serious adverse events, while real, are exceptionally rare and are further minimized through thorough pre-treatment screening.
That said, TMS is a medical treatment and carries real, if uncommon, risks. The best approach is to have an open, detailed conversation with a licensed mental health provider or neurologist who can evaluate your individual medical history, medication list, and risk factors before you begin.
This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting, stopping, or changing any medical treatment.
Ready to Take the Next Step Toward Relief?
Understanding TMS side effects is just the beginning. If you have been living with depression or another condition that has not responded to medication or therapy, TMS may be a path worth exploring with the right clinical team by your side.
At Texas 360 TMS, we walk you through every stage of the process — from your initial evaluation to your final session — so you always know what to expect and feel confident in your care.
Reach out to us today at (512) 360-0805 to find out if TMS therapy is the right fit for you.
