**5. Contraindications and risks of TMS**

The contraindications are mostly related to the exposure of the magnetic field. The absolute contraindication is the presence of ferromagnetic implant in head and neck region, including tattoo on face. Though TMS can be one of the treatments for convulsion, known history of convulsion or suboptimally controlled convulsion, medications that potentially lower seizure threshold and alcoholism may be the exclusion criteria in some of the TMS centers [20]. Heating issue of metallic implant is another concern in patient selection. Eddy currents induced in conductive surface electrodes and implants can cause them to heat up [20]. The temperature increase depends on the shape, size, orientation, conductivity, and surrounding tissue properties of the electrode or implant as well as the TMS coil type, position, and stimulation parameters. Silver and gold are highly conductive and can produce heat excessively, potentially leading to skin burn or even brain tissue damage. Titanium tends to have low heating profile and is safe for TMS [20]. Although there are successful and uneventful TMS treatment done on pregnant ladies [20], pregnancy is still a concern in many centers. Pediatric safety is yet to be confirmed. A systematic review shows that TMS is apparently safe for pediatric patients aged 6 or above [21]. However, there is currently no enough data to demonstrate safety or hazard for individuals below 6 years of age [21].

Transient hearing impairment, convulsion, syncope, local scalp discomfort, headache and acute psychiatric changes have been reported as TMS-related risks [20]. The incidence for significant complications is low. Therefore, TMS is overall a safe procedure. Summary of potential risks is shown in **Table 1** [20].
