Citronellal is a naturally occurring monoterpene aldehyde found in various plant sources, including lemongrass, citronella, and eucalyptus. It has a citrusy, lemon-like aroma and is commonly used in perfumes, cosmetics, and insect repellents. From a chemical perspective, citronellal is an aldehyde with a molecular structure composed of ten carbon atoms. It contains an aldehyde group (-CHO) and a double bond. The (S)-(−)-enantiomer of citronellal makes up to 80% of the oil from kaffir lime leaves and is the compound responsible for its characteristic aroma.

Pharmacologically, citronellal has demonstrated several potential therapeutic properties. It exhibits antimicrobial effects, making it effective against certain bacteria and fungi. Citronellal also displays insect repellent properties, particularly against mosquitoes.

Regarding its relationship with cannabinoids, citronellal does not directly interact with the endocannabinoid system (ECS) like cannabinoids do. However, it is found in cannabis plants and contributes to the overall terpene profile. Terpenes, including citronellal, along with cannabinoids, contribute to the complex aroma and potential therapeutic effects associated with different cannabis strains.