Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that delivers weak electrical currents to targeted brain regions in order to modulate neural activity and potentially enhance cognitive and motor functions. Clinical studies have reported benefits for conditions such as depression, stroke, and Parkinson's disease, typically with only minor and transient side effects. While short-term safety is relatively well established, the long-term effects require more systematic data and therefore require caution. At the same time, tDCS is increasingly being used at home without supervision for extended periods, as devices can be purchased online without prescription or even self-assembled. This situation highlights the need for appropriate safeguards to protect unsupervised users and to ensure that research into supervised long-term use is conducted under ethically acceptable conditions. In this paper, we specifically assess the risks that may arise from prolonged and unsupervised application of tDCS and propose measures that should be implemented by researchers, regulators, and commercial stakeholders involved in the distribution of tDCS devices.