The only absolute contraindication is that the patient has implanted or non-removable metal devices in the head (metal plates, cochlear implants, cerebrospinal fluid diversion valves, aneurysm clips or coils).

It also cannot be used in patients with controlled implants such as pacemakers, implantable defibrillators, vagus nerve stimulators, spinal stimulators or drug infusion pumps.

 As relative contraindications (in which the case would have to be studied in depth to make a decision), we find:

• Epilepsy/seizures in the past.
• Multiple sclerosis.

They are usually mild and improve shortly after the session and tend to improve as the sessions progress. Among them we have the following:

• Discomfort in the stimulation area of the scalp.
• Tingling sensation, spasms, or jerky movements of the facial muscles.
• Stunning (increased hearing acuity).