Citronella refers to aromatic grasses belonging to the Cymbopogon genus, specifically Cymbopogon nardus and Cymbopogon winterianus. This perennial grass is native to tropical regions and is recognized by its powerful, distinct citrus-like fragrance. The strong scent comes from volatile essential oils concentrated within the plant’s leaves and stems, containing compounds like citronellol, citronellal, and geraniol. Due to its potent aroma, citronella is a common ingredient in consumer products globally, raising questions about its safety and internal use.
The Edibility Question: Plant vs. Oil
Determining if citronella can be eaten requires distinguishing between the raw grass and its concentrated essential oil. Although the plant (C. nardus) has been used traditionally for teas or flavoring, it is not preferred for culinary applications due to its strong, less palatable flavor profile. Ingesting the raw grass is generally not recommended, as it lacks the delicate flavor of edible relatives and may cause mild digestive irritation due to its fibrous nature.
The primary safety concern centers on the highly concentrated essential oil derived from the grass. Citronella oil is classified by the U.S. Food and Drug Administration as Generally Recognized as Safe (GRAS) when used in very small quantities as a flavor additive in foods and beverages.
However, consuming the essential oil in larger, undiluted amounts, or in product formulations like insect repellent sprays, is considered unsafe and can lead to poisoning. The concentration of volatile compounds in the oil is significantly higher than in the natural plant, posing a risk of irritation to the respiratory and gastrointestinal systems.
Accidental ingestion of concentrated citronella oil can result in symptoms such as coughing, throat irritation, and stomach upset. Inhalation of the vaporized, highly concentrated oil is also potentially unsafe and has been associated with reports of lung damage. Therefore, citronella oil should never be taken internally as a medicine or supplement without explicit guidance from a healthcare professional.
Common Applications Beyond Ingestion
The most widespread and safest application of citronella oil is its use as a natural insect repellent. The oil works by masking the scents that attract pests, making it difficult for insects like mosquitoes to locate their targets. Citronella is effective against various mosquito species, including those capable of transmitting diseases such as dengue fever and the Zika virus.
The duration of protection is relatively short compared to synthetic alternatives, often lasting less than an hour when applied topically. Formulations often include vanillin, which helps extend the repellent’s effectiveness to potentially a few hours. Citronella oil is commonly incorporated into various products for external use, including candles, sprays, lotions, and incense.
Beyond pest control, the uplifting, refreshing scent of the oil makes it a popular ingredient in the fragrance industry. It is frequently used in soaps, air fresheners, and cosmetics to impart a clean, citrus aroma. Historically, citronella oil has been used in traditional medicine across parts of Asia for its topical properties, including helping to treat rashes, inflammation, and infections, utilizing the oil’s natural antimicrobial and aromatic qualities.
Identifying Citronella and Its Relatives
The most important distinction for preventing accidental consumption is differentiating citronella grass from its highly popular culinary relative, lemongrass (Cymbopogon citratus). Both plants belong to the same genus and share a similar overall appearance, which often leads to misidentification in gardens and markets.
A primary visual difference is the color of the pseudostems, the tightly wrapped leaf bases near the ground. Citronella grass (C. nardus) typically exhibits a slight reddish or purplish tinge at the base, while culinary lemongrass (C. citratus) remains entirely green. Furthermore, citronella tends to grow taller than lemongrass and may feature slightly wider leaf blades.
The olfactory difference is also significant, as the scent profile of the two plants’ oils relies on different chemical compositions. The oil from culinary lemongrass contains high levels of citral, which provides a clean, intense lemon flavor. Citronella oil is dominated by citronellol and citronellal, which results in a stronger, slightly more medicinal or floral scent that is not preferred for cooking.
The Cymbopogon species should not be confused with the common “citronella plant” or “mosquito plant,” which is a scented geranium (Pelargonium citronellum). Although this geranium emits a citrus-like scent and is sometimes marketed as an insect repellent, it is botanically unrelated to the true citronella grass.