Lemongrass

In Brazil the dried leaf is made into a covered hot infusion called an abafado. It is one of the country’s most popular herbal medicines, taken to calm the nerves and help sleep ^{16Reference 16Leite et al. · 1986RCTPharmacology of lemongrass III: assessment of toxic, hypnotic and anxiolytic effects in humans — randomised double-blind controlled clinical trialView study →}.

It is also used for stomach complaints and for high blood pressure ^{18Reference 18Venzon et al. · 2018AnimalEssential oil of Cymbopogon citratus and geraniol, but not citral, promote gastric healing activity in mice — in vivo animal modelView study →}.

In the Caribbean the plant is called fever grass. The hot leaf tea is drunk to promote sweating and break a fever.

Across South and Southeast Asia and West and East Africa, the leaf is taken as a simple hot infusion. It is used to calm the nerves and aid sleep, to settle the stomach and relieve cramping, and to promote sweating in fever.

Lemongrass essential oil, dominated by citral (the geranial/neral pair), inhibits a broad panel of bacteria, dermatophytes and yeasts in vitro ^{3Reference 3Mukarram et al. · 2022ReviewLemongrass essential oil components with antimicrobial and anticancer activities — reviewView study →}. Against Candida and Aspergillus niger it was active in both liquid and vapour phases, and its anti-Candida activity was stronger as a vapour ^{4Reference 4Boukhatem et al. · 2014In vitroLemon grass (Cymbopogon citratus) essential oil as a potent anti-inflammatory and antifungal agent — in vitro and in vivo animal studyView study →}.

It had the lowest minimum inhibitory concentration of four essential oils tested against Candida tropicalis, and a coating of the oil on silicone rubber cut biofilm formation by 45–76% ^{5Reference 5Sahal et al. · 2020In vitroAntifungal and biofilm inhibitory effect of Cymbopogon citratus essential oil on Candida tropicalis — in vitro studyView study →}. This is relevant to the colonisation of prostheses and medical devices.

The oil also acts on the scabies mite Sarcoptes scabiei. At 5% and 10% it killed all mites within 25 and 10 minutes, and it reduced egg hatching at every concentration tested, down to 0.1% ^{6Reference 6Li et al. · 2020In vitroLemongrass oil: a promising miticidal and ovicidal agent against Sarcoptes scabiei — in vitro studyView study →}.

Human evidence is confined to topical and oral-cavity use, such as lemongrass mouthwashes and gels in periodontitis. Potency depends on the oil, and the drunk tea should not be assumed to carry the same effect.

Gap: no controlled trial of systemic or standardised topical antimicrobial efficacy; almost all data are broth or agar assays at concentrations far above what a tea delivers.

Both major fractions are active, by different routes. The essential-oil-free leaf infusion suppresses nitric oxide production and iNOS expression in LPS-stimulated dendritic cells and macrophages, and bio-guided fractionation traced the effect to its polyphenols ^{7,8Reference 7Figueirinha et al. · 2010In vitroAnti-inflammatory activity of Cymbopogon citratus leaf infusion in LPS-stimulated dendritic cells: contribution of the polyphenols — in vitroView study →Reference 8Francisco et al. · 2011In vitroCymbopogon citratus as source of anti-inflammatory compounds: bio-guided assay in LPS-stimulated macrophages — in vitroView study →}. In macrophages the infusion also inhibited NF-κB activation and PGE₂ production, but it did not change COX-2 expression ^{8Reference 8Francisco et al. · 2011In vitroCymbopogon citratus as source of anti-inflammatory compounds: bio-guided assay in LPS-stimulated macrophages — in vitroView study →}.

In human macrophages the infusion reduced expression of the cytokines TNF-α and CCL5. Chlorogenic acid, the infusion’s main phenolic acid, was identified as a contributor, acting through inhibition of the proteasome and the NF-κB pathway ^{9Reference 9Francisco et al. · 2013In vitroAnti-inflammatory activity of Cymbopogon citratus infusion via proteasome and NF-κB inhibition: contribution of chlorogenic acid — in vitroView study →}.

Applied to the skin in an emulsion, the infusion and its polyphenol fractions reduced carrageenan-induced paw oedema in rats by 30–59% ^{10Reference 10Costa et al. · 2016AnimalPolyphenols from Cymbopogon citratus leaves as topical anti-inflammatory agents — in vivo animal modelView study →}.

The citral-rich oil is also active in rodents: 10 mg/kg by mouth reduced paw oedema about as much as diclofenac, and applied to the ear it reduced croton-oil oedema ^{4Reference 4Boukhatem et al. · 2014In vitroLemon grass (Cymbopogon citratus) essential oil as a potent anti-inflammatory and antifungal agent — in vitro and in vivo animal studyView study →}. A 2025 profiling study found both an ethanol extract and the oil active in protein-denaturation and membrane-stabilisation assays ^{11Reference 11Sari et al. · 2025In vitroUHPLC-MS/MS and GC-MS profiling and anti-inflammatory effect of the ethanol extract and essential oil of Cymbopogon citratus — in vitroView study →}.

Gap: no clinical anti-inflammatory endpoint; the infusion and oil work through different chemistry, so “lemongrass is anti-inflammatory” hides which preparation and dose is meant.

Lemongrass essential oil scavenges DPPH radicals and protected red blood cells from lipid peroxidation when they were incubated in high-glucose media ^{12Reference 12De Oliveira e Silva et al. · 2022In vitroCymbopogon citratus protects erythrocytes from lipid peroxidation in vitroView study →}.

The antioxidant activity of an essential-oil-free leaf extract depended on how it was formulated into capsules ^{13Reference 13Sousa et al. · 2021In vitroFormulation effects in the antioxidant activity of extract from the leaves of Cymbopogon citratus — in vitroView study →}. The same activity has been reported alongside cell protection in cancer-cell studies ^{14Reference 14Pan et al. · 2022In vitroIn vitro evaluation of antioxidant and anticancer activity of lemongrass in cervical cancer cells — in vitroView study →}.

Gap: all of this is cell-free or cell-culture work. No human study has measured an antioxidant biomarker after lemongrass intake.

In mice, the essential oil at 10 mg/kg by mouth produced anxiolytic-like behaviour that was reversed by flumazenil, which points to the GABA-A/benzodiazepine site ^{15Reference 15Costa et al. · 2011AnimalThe GABAergic system contributes to the anxiolytic-like effect of essential oil from Cymbopogon citratus — mouse in vivoView study →}. It had no antidepressant effect in the same study, and it lengthened sleeping time only at higher doses ^{15Reference 15Costa et al. · 2011AnimalThe GABAergic system contributes to the anxiolytic-like effect of essential oil from Cymbopogon citratus — mouse in vivoView study →}.

A 1986 double-blind trial tested the traditional Brazilian tea in people. In 50 volunteers it had no effect on sleep compared with placebo, and in 18 people with high trait anxiety it did not reduce anxiety in an anxiety-inducing test ^{16Reference 16Leite et al. · 1986RCTPharmacology of lemongrass III: assessment of toxic, hypnotic and anxiolytic effects in humans — randomised double-blind controlled clinical trialView study →}.

The positive human result comes from inhaled aroma. In a 2025 randomised trial of 38 patients having dental scaling, inhaling lemongrass oil lowered anxiety scores, blood pressure and heart rate compared with scaling alone ^{17Reference 17Maybodi et al. · 2025RCTEffect of aromatherapy with lemongrass on the anxiety of patients undergoing scaling and root planing — randomised controlled trialView study →}.

Gap: the only positive human data are for inhalation in an acute procedural setting, against a no-treatment control. There is no evidence that the oral tea treats anxiety or insomnia.

In mice, the essential oil, citral and geraniol all protected against ethanol-induced gastric ulcers, with citral reducing ulcer area most at its effective dose ^{18Reference 18Venzon et al. · 2018AnimalEssential oil of Cymbopogon citratus and geraniol, but not citral, promote gastric healing activity in mice — in vivo animal modelView study →}.

On established acetic-acid ulcers the results diverged. The oil and geraniol sped healing by about 35% and 81%, but citral did not ^{18Reference 18Venzon et al. · 2018AnimalEssential oil of Cymbopogon citratus and geraniol, but not citral, promote gastric healing activity in mice — in vivo animal modelView study →}.

Gap: this is a single study in one species, with no clinical dyspepsia or ulcer data.

An aqueous lemongrass extract reduced the viability of prostate cancer cells (DU-145), improved the activity of docetaxel against them, and did not harm normal VERO cells ^{19Reference 19Gomes et al. · 2021In vitroLemongrass presents antitumoral effect and improves chemotherapy activity in prostate cancer cells — in vitroView study →}. A lemongrass extract was also cytotoxic to cervical cancer cells (SiHa) ^{14Reference 14Pan et al. · 2022In vitroIn vitro evaluation of antioxidant and anticancer activity of lemongrass in cervical cancer cells — in vitroView study →}. Leaf essential oils were cytotoxic to several lung cancer cell lines and induced apoptosis and cell-cycle arrest in A549 cells ^{22Reference 22Trang et al. · 2020In vitroEssential oils of lemongrass induce apoptosis and cell-cycle arrest — in vitroView study →}.

Lemongrass oil and citral increased the cytotoxicity of doxorubicin in drug-resistant breast, liver and ovarian cancer cells, by interfering with the efflux pumps that remove the drug ^{21Reference 21Mukhtar et al. · 2023In vitroCymbopogon citratus and citral overcome doxorubicin resistance in cancer cells — in vitroView study →}.

The selectivity is limited. Leaf fractions, the essential oil, citral and geraniol were also cytotoxic to normal human white blood cells and damaged red-cell membranes at higher concentrations ^{20Reference 20Mendes Hacke et al. · 2022In vitroCytotoxicity of Cymbopogon citratus fractions, essential oil, citral and geraniol in human leukocytes and erythrocytes — in vitroView study →}.

Gap: cell-line work at concentrations no dietary or tea intake reaches, with no in vivo tumour, pharmacokinetic or human data.

Mice given lemongrass essential oil for 21 days had lower blood cholesterol at the highest dose, 100 mg/kg, with no genotoxicity ^{23Reference 23Costa et al. · 2011AnimalCholesterol reduction and lack of genotoxic or toxic effects in mice after repeated 21-day oral intake of lemongrass essential oil — in vivo animal modelView study →}. In vitro, the leaf infusion and its polyphenol fractions disrupted the micelles needed for intestinal cholesterol absorption ^{24Reference 24Da Ressurreição et al. · 2022In vitroEffect of phenolic compounds from Cymbopogon citratus leaves on cholesterol micelle formation — in vitroView study →}.

In the 1986 human trial, the tea produced no change in serum cholesterol, triglycerides or other lipids ^{16Reference 16Leite et al. · 1986RCTPharmacology of lemongrass III: assessment of toxic, hypnotic and anxiolytic effects in humans — randomised double-blind controlled clinical trialView study →}. The animal effect used the concentrated oil, not the drunk infusion.

Gap: the one human dataset is null; the positive evidence is a single rodent study using a different preparation, and no lipid RCT exists.

The tea. In healthy volunteers given the traditional Brazilian tea as a single dose or daily for two weeks, blood tests of liver and kidney function, glucose and lipids stayed normal, as did urinalysis, EEG and ECG ^{16Reference 16Leite et al. · 1986RCTPharmacology of lemongrass III: assessment of toxic, hypnotic and anxiolytic effects in humans — randomised double-blind controlled clinical trialView study →}. Some volunteers showed slight rises in direct bilirubin and amylase, with no symptoms ^{16Reference 16Leite et al. · 1986RCTPharmacology of lemongrass III: assessment of toxic, hypnotic and anxiolytic effects in humans — randomised double-blind controlled clinical trialView study →}.

The essential oil. The oil irritates skin and mucous membranes. Dilute it for topical use and do not swallow it undiluted. In mice, its acute oral LD50 was about 3,500 mg/kg, and 21 days at up to 100 mg/kg caused no organ damage and no genotoxicity ^{23Reference 23Costa et al. · 2011AnimalCholesterol reduction and lack of genotoxic or toxic effects in mice after repeated 21-day oral intake of lemongrass essential oil — in vivo animal modelView study →}.

Allergy. Lemongrass oil and citral are recognised contact allergens in fragrance-sensitive people. A patch test before using the oil on the skin is sensible.

Interactions. No drug interaction has been shown in people, and none has been formally studied.