Is it biologically plausible to use millimetre and terahertz waves for therapeutic applications?

There are many diagnostic and therapeutic situations where presently available tools (physical, chemical, biological) are insufficient. The search for improved approaches includes investigations of the usefulness of millimetre (MMW) and terahertz waves (THz). Here we investigated if published in vivo and in vitro studies provide support for the use of these waveforms in therapeutic applications, during conditions that do not cause tissue heating. Our conclusion is that there is some evidence for that both MMW and THz can influence biological systems in a manner that is not obviously driven by tissue heating. However, the number of relevant studies is very low which limits the drawing of any far-reaching conclusions.