Short answer: lemongrass essential oil is a citral-rich distilled oil, commonly from Cymbopogon citratus or C. flexuosus. Laboratory antimicrobial findings are plentiful, but human evidence is much smaller. A recent dental study is interesting, not a licence for broad anxiety or infection claims.
Identity matters
Lemongrass refers to more than one aromatic grass. Cymbopogon citratus is an accepted species in Kew’s Plants of the World Online. East Indian lemongrass is often labelled C. flexuosus. Citronella oils come from related species but should not be sold as though the names were interchangeable.
The essential oil is normally steam-distilled from the leaves. Lemongrass tea, culinary stalks, aqueous extracts and distilled oil are different preparations. Evidence or food experience for one does not automatically settle the safety or effect of another.
Aroma and composition
The sharp lemon aroma is largely due to citral, a mixture of geranial and neral. The proportions of citral, myrcene, geraniol and other constituents vary with species, cultivation, harvest and distillation. The US National Library of Medicine records citral as a defined chemical substance, but a complete lemongrass oil is a variable mixture rather than pure citral.
Anxiety research
A 2025 randomised clinical study compared lemongrass aroma with no aromatherapy during non-surgical periodontal treatment. Thirty-eight adults took part. The authors reported changes in anxiety and some haemodynamic measures.
The study is directly relevant to dental anxiety, but it was small, used one short procedure and could not blind participants to an obvious smell. It does not establish treatment for generalised anxiety disorder, panic disorder or chronic stress. Replication with a credible scent control and larger samples would increase confidence.
Claims that lemongrass “calms the nervous system” often cite animal experiments or isolated constituents. Those studies may investigate mechanisms, but they do not replace human clinical outcomes.
Antimicrobial and anti-inflammatory research
A laboratory study found antifungal and anti-inflammatory effects for a tested C. citratus oil. Another laboratory study reported inhibition of several fungi and yeasts. These experiments use controlled concentrations and direct contact that a diffuser or casual skin application does not reproduce.
Laboratory inhibition does not show that the oil treats thrush, athlete’s foot, scalp disease, chest infection or contaminated indoor air. Human infection treatment also needs diagnosis, a safe delivery method and evidence that benefit exceeds harm.
A 2024 scoping review examined possible clinical uses of lemongrass oil, including oral-care formulations. A scoping review maps available studies; it does not by itself establish that every included formulation works or that neat oil is safe in the mouth.
Skin safety and citral
Citral can irritate skin and is a recognised fragrance allergen. The European Commission’s Scientific Committee on Consumer Safety assessed citral in relation to skin sensitisation and noted remaining uncertainties in the risk-assessment method even at proposed cosmetic concentrations.
This is not a reason to assume that an arbitrary home dilution is safe. Finished cosmetics use controlled formulas, while a drop-based recipe varies with the dropper, carrier and total volume. Avoid neat application, damaged skin, eyes and mucous membranes. Stop after burning, redness, itching or swelling.
Inhalation and household use
Lemongrass has a powerful aroma. Diffuse briefly at low intensity with ventilation, not continuously in a closed room. Stop if anyone develops coughing, wheeze, headache or nausea. A fresh smell does not measure air disinfection or indoor-air quality.
Do not use a culinary history to justify swallowing a concentrated oil. Keep the bottle out of reach of children and pets and follow the finished product’s directions.
Buying checks
- The label names Cymbopogon citratus or C. flexuosus.
- Leaf and steam distillation are stated.
- A batch number and current composition report are available.
- The supplier gives conservative skin and inhalation directions.
- Citronella, lemon oil and lemongrass are not confused.
- Laboratory antimicrobial findings are not advertised as clinical proof.
My assessment
Lemongrass oil has a well-established fragrance identity, substantial laboratory research and limited emerging human evidence. The small dental-anxiety trial deserves accurate reporting, but it does not support broad treatment claims. Citral-related irritation and allergy are central practical concerns.
Sources
- Kew Plants of the World Online: Cymbopogon citratus
- Randomised study of lemongrass aroma during periodontal treatment
- Scoping review of clinical uses of lemongrass essential oil
- Laboratory antifungal and anti-inflammatory study
- Laboratory study of fungal and yeast inhibition
- EU Scientific Committee on Consumer Safety opinion on citral