Safety & Side Effects — What to Expect
A detailed guide to rTMS safety: common and rare side effects, contraindications, and comparison with pharmacotherapy. By Dr Paschalis Gkikas, Medical Director of Smart CNS Center.
Introduction
Repetitive Transcranial Magnetic Stimulation (rTMS) is an approved, non-invasive treatment with a well-documented safety profile. Learn exactly what rTMS and iTBS are. It has been used clinically for more than 25 years, and available data — from both clinical studies and international clinical practice — confirm that it is one of the safest options within the spectrum of mental health treatments.
This page clearly answers the questions patients often ask before starting treatment: what they may feel, what is rare, and in which cases the treatment is not indicated.
Common side effects
The side effects of rTMS are generally mild, local, and temporary. They mainly appear at the beginning of treatment and usually improve as the body becomes accustomed to the stimulation.
Headache or pressure in the head
This is the most common side effect, reported by approximately 1 in 3 patients during the first sessions. It is usually mild, located around the stimulation site, and resolves within a few hours — usually without analgesics. In most cases, it decreases or disappears after the first 3–5 sessions.
Local scalp discomfort
During the session, some patients feel a mild tapping or tingling sensation at the contact point. It is not painful and stops immediately when the session ends.
Facial muscle twitches
Some patients notice mild involuntary contractions of muscles near the stimulation site during the session. This is an expected phenomenon, does not indicate a problem, and resolves spontaneously.
Mild fatigue
Some patients report tiredness after the first sessions. It does not require rest or avoidance of daily activities.
Rare side effects
Seizure
This is the most serious possible complication, with an estimated frequency below 0.1% — fewer than 1 in 1,000 treatment courses — in appropriately selected patients. The risk is minimized through proper pre-treatment assessment and strict exclusion of patients with a history of epilepsy or other risk factors. At Smart CNS Center, every patient is assessed thoroughly before treatment begins.
Mood changes during treatment
Rarely, some patients with bipolar disorder may experience a change in mood state during a treatment course. For this reason, monitoring during treatment is an integral part of the protocol.
Hearing
The rTMS mechanism produces a repeated clicking sound. Although the intensity is not considered harmful, the use of earplugs during the session is standard precautionary practice.
Contraindications — who cannot receive rTMS
Assessment of contraindications is a mandatory step before any treatment.
Absolute contraindications:
- Metallic implants inside or near the skull, such as vascular clips, cochlear implants, or neurostimulators.
- Older-generation cardiac pacemaker or implantable defibrillator.
Relative contraindications, assessed on a case-by-case basis:
- Epilepsy.
- Severe history of head injury.
- Concurrent use of medications that lower the seizure threshold.
- Pregnancy, depending on the case and indication.
- Unstable psychiatric or medical condition.
Comparison with medication
rTMS does not have the systemic side effects typically associated with antidepressants or other psychiatric medications.
It does not usually cause:
- Weight gain.
- Sexual dysfunction.
- Gastrointestinal symptoms.
- Sedation.
- Cognitive slowing.
- Dependence or withdrawal syndrome.
This does not mean that rTMS replaces medication in every patient. In many cases it is used as an adjunctive treatment, while in others it may allow a gradual reduction of medication, always under medical supervision.
What happens if discomfort appears?
If discomfort appears during a session, the protocol can be adjusted immediately. The physician can change the position of the coil, modify the stimulation intensity, or pause the session if necessary.
Treatment is not performed mechanically. Each session is monitored clinically.
Safety conclusion
rTMS is one of the safest modern neuromodulation treatments when applied correctly, with appropriate medical assessment, individualized parameter selection, and ongoing monitoring.
For most patients, the expected side effects are mild and temporary. Serious complications are very rare when international safety rules are followed. See more frequently asked questions.
