When you apply certain substances to your skin and later perceive their taste, it might seem puzzling. This phenomenon has a scientific basis rooted in how the body interacts with external compounds.
How Skin Absorbs Substances
The skin acts as a protective barrier against the external environment. This barrier is primarily formed by the epidermis, specifically its outermost layer called the stratum corneum. The stratum corneum consists of tightly packed dead skin cells embedded in a lipid matrix, resembling a “bricks and mortar” structure that limits the entry of foreign substances.
Despite this protective function, certain substances can penetrate the skin through various pathways. Molecules can diffuse directly across the skin cells (transcellular pathway) or move through the lipid-rich spaces between cells (intercellular pathway). Hair follicles and sweat glands also offer routes for absorption. The extent to which a substance is absorbed depends on factors such as its concentration, the duration of contact, its solubility (lipid-soluble compounds penetrate more easily), and its molecular weight.
The Body’s Pathway to Taste
Once a substance penetrates the skin’s barrier layers, it enters the deeper tissues. From the epidermis, it moves into the dermis, which contains a rich network of blood vessels. In the dermis, the absorbed compounds are then picked up by the capillaries and enter the bloodstream, a process known as systemic absorption.
The circulatory system then distributes these compounds throughout the body, including to the oral cavity. When these substances reach the taste buds on the tongue, they can trigger taste receptors, leading to the perception of a taste. While often perceived as taste, the sensation can also involve olfactory receptors, as smell plays a significant role in flavor perception.
Everyday Examples of Absorption
Essential oils, known for their strong aromas and lipophilic nature, are frequent examples. For instance, applying peppermint oil to the skin might result in a minty taste in the mouth, as its volatile compounds are readily absorbed and circulated. Similarly, strong-smelling compounds like those found in garlic can be absorbed through the skin and subsequently detected as a taste or odor.
Topical medications are another category where this can occur. Nicotine patches, designed for transdermal delivery, release nicotine into the bloodstream, and some users report a distinct taste, sometimes described as peppery or even slightly fishy. Certain pain relief creams containing active ingredients that can be absorbed systemically might also lead to a subtle taste perception. The amount absorbed is typically small, but enough to activate the highly sensitive taste and smell receptors. This absorption is influenced by the area of skin exposed, the duration of contact, and the specific properties of the substance.
Understanding Potential Risks
The perception of taste from skin application is generally not a concern, as the amount absorbed is usually minimal. For instance, the small quantities of essential oils or topical creams that lead to a taste are unlikely to cause harm. However, this indicates the substance has entered the bloodstream, highlighting the skin’s permeability.
There are situations where skin absorption can pose risks. Exposure to toxic substances, especially in large quantities or for prolonged periods, can lead to systemic effects. Damaged skin, such as from burns or abrasions, has increased absorption, making it more susceptible to harm. If unusual symptoms accompany the taste perception, such as widespread rash, dizziness, nausea, or breathing difficulties, it could indicate significant absorption and warrants medical attention. In cases of suspected poisoning, immediately remove contaminated clothing and rinse the affected skin area with plenty of water for 15 to 20 minutes, then contact a poison control center.