Geranium, particularly the essential oil extracted from species such as Pelargonium graveolens, has been scientifically studied for its insect repellent properties. The primary compounds found in geranium oil, such as citronellol and geraniol, are known for their ability to repel mosquitoes and other insects. Several laboratory and field studies have demonstrated that geranium essential oil, alone or in combination with other plant oils, can provide moderate protection against bites from mosquitoes, ticks, and other insects. For example, a study published in Parasite (2011) found that geranium oil exhibited significant repellent activity against Aedes aegypti, a common mosquito species.

However, while the insect repellent effects of geranium oil are scientifically validated, they are generally less potent and shorter-lasting compared to synthetic repellents such as DEET. The evidence base is moderate: results vary depending on oil concentration, formulation, and the target insect species. Geranium oil is often included in commercial natural insect repellents, leveraging both its scent and documented efficacy. Safety is another consideration; while generally regarded as safe when used topically in diluted form, it can cause skin irritation in some individuals.

In summary, scientific evidence supports the use of geranium oil as a mild to moderate insect repellent, though it is not a complete substitute for more potent synthetic options, especially in areas with high insect-borne disease risk.