Plants have been providing medicinal value for thousands of years, if not all of human existence. However, it wasn’t until 1661 that the term “sublingual” was developed, coinciding with the discovery of the salivary and other glands under the tongue. Sublingual is Latin, and translates literally to “under the tongue”.
Humans may have been taking their herbal medicines sublingually without realizing it as far back as 1000 AD (when Egypt documented making tinctures after the distillation of alcohol was discovered), or even further back with rudimentary pastes and “chews” of plants. They didn’t know it at the time, but sublingual absorption provides a direct line to the nervous system, rather than the digestive system.
Taking medicine sublingually means administering it directly under the tongue, so that the compounds enter directly into the bloodstream, crossing the blood-brain barrier through especially permeable tissue in the floor of the mouth.