Geraniol is a naturally derived ingredient that is added to cosmetics and personal care products as a fragrance due to its pleasant floral scent.
Geraniol is a terpene alcohol occurring in the essential oils of several aromatic plants. Terpenes are a large and diverse class of organic compounds produced by a variety of plants. They often have a strong scent and may protect the plants that produce them by deterring herbivores and by attracting predators and parasites of herbivores.
Geraniol is the primary component of rose oil, palmarosa oil, and citronella oil (Java type). It also occurs in small quantities in geranium, lemon, and many other essential oils. Furthermore, geraniol is produced by the scent glands of honeybees to mark nectar-bearing flowers and locate the entrances to their hives.
Geraniol is also synthetically produced, with global production exceeding 1,000 metric tons per year. It appears as a clear to pale-yellow oil which is insoluble in water, but soluble in most organic solvents.
Geraniol has characteristic rose-like scent, which is why it functions as a fragrance ingredient in a variety of cosmetics and personal care products. A survey of consumer products revealed that it is present in 76% of investigated deodorants on the European market, included in 41% of domestic and household products, and in 33% of cosmetic formulations based on natural ingredients.
In addition to functioning as a fragrance ingredient, geraniol is also used in flavors such as peach, raspberry, plum, citrus fruits, watermelon, pineapple and blueberry. The pleasant flavor of geraniol makes it a useful ingredient for lip care products, such as lip gloss and lip balm.
Geraniol can also function as an effective plant-based insect repellent. Studies have proven geraniol to be effective in repelling mosquitoes. In fact, geraniol has significantly more mosquito repellent activity than citronella or linalool in both indoor and outdoor settings.
Research has found that geraniol exhibits various biochemical and pharmacological properties. For instance, geraniol can function as an antimicrobial agent due to its solubility in the phospholipid bilayer of cell membranes. In 2002, Friedman et al. evaluated the bactericidal activity levels of 96 essential oils and 23 oil compounds (including geraniol) against Campylobacter jejuni, E.coli, Listeria monocytogenes and Salmonella enterica. This research demonstrated that geraniol was most active against E. coli, L. monocytogenes, and S. enterica.
Finally, geraniol has been investigated for use as a penetration enhancer. The enhancing power of geraniol enables it to be used as a carrier for other molecules that are unable to cross skin barriers alone. In fact, geraniol and other terpenes are used to improve transdermal drug delivery because they are reported to have good toxicological profiles, high percutaneous enhancement abilities, and negligible skin irritancy at low concentration (1 to 5%).
The Food and Drug Administration (FDA) includes geraniol on its lists of flavoring substance considered Generally Recognized As Safe (GRAS).
The safety of geraniol has been evaluated by the Research Institute for Fragrance Materials Expert Panel (REXPAN). Based on this evaluation, an International Fragrance Association (IFRA) Standard has been established which restricts the use of geraniol in fragrances because of potential sensitization. In addition, geraniol is listed on the European Union’s 26 fragrance allergens that must be identified on cosmetic and detergent product labels.
According to EWG, geraniol is rated as a 7 on a scale of 1 to 10, with 1 being the lowest risk to health and 10 being the highest. The main concern cited by EWG regarding geraniol is “known human immune system toxicant or allergen”.
Studies have reported that geraniol had the potential to autoxidize upon air exposure. This means that when products containing geraniol are applied to the skin, the exposure to air causes the unstable geraniol molecule to oxidize, which is believed to trigger aggravation on skin.
Due to the possibility of an allergic reaction, those with sensitive skin should try to avoid geraniol or perform a patch test with any product containing this ingredient.
References: Wikipedia, “Geraniol”, Wikipedia, “Terpenes”, South African Journal of Botany; 76(4) Oct 2010, 643-651, Cosmetics Info, “Geraniol”, EWG’s Skin Deep Cosmetic Database, “Geraniol”.