When inhaled, CBD and THC are immediately absorbed through the lungs, resulting in a faster response and greater bioavailability compared to oral products. When applied topically to the skin, they are absorbed through the epidermis or hair follicles while interacting with receptors to provide localized effects. Cannabis skin products are applied directly to the skin. Thus, THC can be absorbed through CB1 receptors in skin, muscle tissues and nerves, producing anti-inflammatory and pain-relieving effects in users.
Therefore, THC can be technically absorbed by the skin, but not actually through the skin. You see, your skin or epidermis, as scientists would call it, is your protective barrier. Part of the reason we can experience the benefits of cannabis is that the human body has a natural endocannabinoid system. This system works throughout the body and regulates a variety of functions, from sleep to experiencing pain.
The cannabinoids in the cannabis-infused topical lotion work by penetrating muscles and joints, where they act as a supplement to the endocannabinoid system. In other words, THC can be absorbed through the skin, but that doesn't mean that THC lotion makes you drug. The skin absorbs THC oil and allows THC to interact with the endocannabinoid system (ECS). However, it does not pass from the outermost layer of the skin into the bloodstream.
However, products such as RSO pain oil that can be consumed both orally and topically can cause THC to be present in saliva.