Licorice root, sourced from the plant Glycyrrhiza glabra, is a popular botanical ingredient in many skincare formulations. It is valued for its ability to brighten the skin, reduce hyperpigmentation, and provide anti-inflammatory effects. Despite these cosmetic benefits, scientific evidence suggests specific concerns regarding the use of this ingredient during pregnancy. These risks are linked to a potent molecule within the plant that can interfere with a sensitive biological process.
Identifying the Compound of Concern
The primary chemical constituent responsible for both the beneficial effects and the potential risks of licorice root is glycyrrhizin. This compound is metabolized by intestinal bacteria and liver enzymes into its biologically active form, glycyrrhetinic acid. Glycyrrhetinic acid is the molecule that directly interacts with human physiology to produce systemic effects. Although skincare labels may list Glycyrrhiza glabra extract, caution is warranted due to the concentration of glycyrrhizin and glycyrrhetinic acid molecules. The potential for harm is directly proportional to the amount of this compound that reaches the maternal bloodstream.
The Physiological Mechanism of Risk
The concern surrounding glycyrrhetinic acid during pregnancy centers on its powerful inhibitory effect on a specific placental enzyme. This enzyme is known as 11-beta-hydroxysteroid dehydrogenase type 2, or 11-beta-HSD2. The biological role of placental 11-beta-HSD2 is to act as a protective barrier for the developing fetus. Maternal cortisol, the body’s main stress hormone, circulates at high concentrations. The 11-beta-HSD2 enzyme rapidly converts most cortisol into an inactive form called cortisone as it crosses the placenta.
This process ensures that only about 10 to 15 percent of the maternal cortisol reaches the fetus. Glycyrrhetinic acid competitively inhibits this enzyme, effectively dismantling this natural placental barrier. When 11-beta-HSD2 is inhibited, a greater proportion of active maternal cortisol floods the fetal environment. Observational studies have linked high maternal consumption of glycyrrhizin to consequences such as a higher risk of earlier delivery.
Further research suggests that this increased fetal cortisol exposure may be associated with altered neurodevelopment. Studies have observed that children exposed prenatally to high levels of glycyrrhizin exhibited differences in cognitive performance and behavioral patterns years later. This exposure has been linked to lower scores on intelligence and memory tests, and an increased risk of attention deficit and hyperactivity.
Comparing Topical Absorption to Oral Intake
A significant distinction exists between the systemic exposure achieved through oral consumption of licorice products and that from topical skincare application. Oral intake, such as from candy or supplements, introduces a large, concentrated dose directly into the digestive system for systemic absorption. This route results in high systemic exposure, which is why many health organizations advise against consuming licorice products during pregnancy. Topical application relies on transdermal absorption, where a substance passes through the skin layers into the bloodstream. Glycyrrhetinic acid is generally considered poorly absorbed through the skin, suggesting a much lower systemic level compared to oral dosing.
Determining the precise rate of transdermal absorption is challenging, as it depends on factors like the product’s concentration, the application area’s size, and the duration of contact. Despite the lower absorption rate, the risk is not considered negligible, particularly with frequent, widespread use of high-concentration products. Since the mechanism of action involves a potent enzyme inhibitor, even a small, sustained systemic dose from topical use could theoretically disrupt the placental barrier. Because ethical studies cannot establish a safe topical threshold in pregnant women, the scientific stance is one of elevated caution.
Clear Guidelines for Use During Pregnancy
Given the established mechanism of risk and the uncertainty regarding systemic absorption from skincare, guidelines recommend caution or avoidance. The potential for glycyrrhetinic acid to bypass the placental barrier’s protective function warrants a precautionary approach throughout the pregnancy. This aligns with the general principle of limiting exposure to non-essential, biologically active compounds that could affect fetal development.
Expectant mothers should review the ingredient lists of all skincare products they use. The compounds to look for include “Licorice Root Extract,” “Glycyrrhiza glabra,” and derivatives used in cosmetic chemistry, such as Dipotassium Glycyrrhizate. Consulting a healthcare provider or dermatologist regarding the safety of specific products is the most prudent course of action.