Safety and tolerability

Abstract

TDCS most common adverse effects are burning, tingling, itching, headache, and discomfort on the site of stimulation. These adverse effects occur in up to one-third of patients and are generally mild, short-lived, and well-tolerated. Skin redness is a common adverse effect that occurs in most patients, although skin burning is rare and often associated with repeated tDCS sessions and poor humidification of sponges. Severe adverse effects, including seizures, cardiac arrest, permanent disability and damage, have not been reported in tDCS adult trials thus so far. Regarding safety, studies indicate that the doses used clinically are much lower than necessary to induce lesions and are not associated with damage. Nonetheless, the statement that tDCS is "safe" should be tempered down considering that its adverse effects are often underreported in most studies and the risk of induction of adverse effects in special populations (e.g., hypomanic switch in depressed patients, or seizures in patients with epilepsy) has not been sufficiently investigated yet.