Citronella Oil.
Research-backed compound with potential health benefits. It's a plant-based insect repellent. The strong smell messes with mosquitoes' ability to find you. Some topical use for fungal issues, but the evidence is weaker.
Reviewed March 2026
- Category
- Compound
What Citronella Oil is, and what it does.
- Does it work
- Suits people who want a plant-derived way to keep mosquitoes off skin and clothing, and anyone formulating aromatic sprays or candles. It is a topical and aromatic material, not a daily capsule.
- How much to take
- For skin, dilute 3-5 drops into an ounce of carrier oil. For a diffuser, 3-5 drops. Don't swallow it. Zero is the correct oral dose.
- Time to feel it
- Straight away as a smell, and mosquitoes back off while the oil is still on your skin. Reapplication is usually needed within an hour or two as the terpenes evaporate.
- The first dose
- You'll immediately smell it. If you're outside, you'll notice fewer bugs bothering you. That's it.
- With regular use
- No long-term 'buildup' benefits. Its effects are immediate and temporary. You reapply it when you need it.
- How well tolerated
- Topically, it's well tolerated in most when diluted. Undiluted can cause skin irritation. Ingesting it is a bad idea. Can cause nausea, vomiting, and more serious issues.
- How it feels
- A strong, fresh, lemony smell. Oily on the skin. You feel protected from bugs, not 'healthier'.
- The overlooked benefit
- Citronellal is an aldehyde and oxidises in air and light, so an old open bottle is not the same material you bought. Keep it dark, closed and cool and it stays true for far longer.
50 to 200mg a day is where Citronella Oil works.
Source: Trop Med Int Health. 2011;16(10):1249-1261. Citronella as insect repellent.
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
Citronella Oil is documented in the library; the clinical read is in the queue. Nothing about the strength of the research prints until the read is done.
- mosquito repellency on treated skinRandomised trial
- duration of repellent protectionNarrative review
- antimicrobial activity in laboratory assaysIn vitro study
- topical antifungal activityRandomised trial
Questions people ask about Citronella Oil.
- Can I drink it if I dilute it?
- No. Please don't. It's not for internal use, period.
- Is it safe for kids?
- Not recommended for kids under 2. For older kids, use a very diluted version and test a small patch of skin first.
- Does it work as well as DEET?
- Not quite, and you have to reapply it more often. But it's a solid plant-based alternative if you want to avoid DEET.
- Can I put it directly on my skin?
- Bad idea. It's potent. Always mix it with a 'carrier oil' like coconut, jojoba, or almond oil first.
- Will it stain my clothes?
- Yes, it's an oil. It can leave a greasy spot on fabric.
- Is it safe for dogs or cats?
- No. It can be toxic to pets, especially cats, both on their skin and in a diffuser. Best to avoid using it around them.
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Linalool is a major constituent of both lavender oil and several citronella chemotypes, so the two share terpene alcohol chemistry and blend without one dominating the aroma. The pairing is conventional in topical and diffuser formulations.
Cineole is a small, highly volatile oxide that evaporates faster than the citronellal and geraniol of citronella, so a blend gives an early and a sustained release phase. Formulators pair fast and slow evaporating terpenes for that reason.
Citronella oil is used diluted, and medium chain triglycerides dissolve its terpenes fully while slowing evaporation from the surface. This is the standard carrier pairing for volatile botanical oils.
Citronellal and geraniol oxidise readily to acids and epoxides on air exposure, which changes the aroma and the skin profile of the oil. Tocopherols scavenge the lipid peroxyl radicals that drive that change.
Citronella oil is a mix of volatile terpenes and is effectively insoluble in water. Lecithin is an amphiphilic phospholipid that emulsifies it into a stable dispersion. Without an emulsifier the oil separates and the dose delivered per serving becomes unpredictable.
Phospholipid emulsifiers keep an essential oil dispersed in an aqueous or semi-solid base. This is standard practice for any terpene oil going into a water-containing product. It changes delivery, not chemistry.
Medium-chain fatty acids and their triglycerides dissolve monoterpenes readily and are the usual dilution carrier for a neat essential oil. Diluting into a fixed oil lowers the concentration on a surface and slows evaporation of the volatile fraction. Carrier choice is a delivery decision.
Rosemary extract supplies carnosic acid and rosmarinic acid, which are used across the industry as oxidation inhibitors in oils. Citronella oil oxidises at its aldehyde and terpene positions on exposure to air and light, forming compounds that were not in the fresh oil. Adding a phenolic antioxidant slows that shift. The benefit is to the product, not to the person.
Thymol-rich thyme oil and citronellal-rich citronella oil are both lipophilic terpenoids that partition into microbial membranes and raise permeability in laboratory assays. Blends of essential oils commonly show additive effects in those assays. This is in vitro membrane chemistry and not a demonstration of any effect in a person.
Carvacrol and citronella terpenes act on the same lipid membrane target in culture, and mixed essential oil blends are a common approach in feed and preservative work. The candidate poultry work in this record measured a blend rather than citronella alone. Read any additive effect as measured in vitro or in animals.
Menthol and citronellal are both cooling, sharply aromatic monoterpenoids and are blended for scent and for combined volatility. Blending changes the evaporation profile of the mixture, since the components have different vapour pressures. The pairing is aromatic rather than nutritional.
Lemon balm oil is itself rich in citronellal and geranial, the same aldehydes that define citronella. Blending the two concentrates one chemical class rather than adding a new one. Anyone reacting to citronellal would encounter it in both.
Squalane is a saturated, oxidation-resistant hydrocarbon used as a topical carrier. It dissolves terpene oils and holds them on the skin surface longer than a volatile solvent would. The trade-off is a heavier feel than an alcohol base.
Carotenoids are highly oxidation-sensitive and compete for the same limited antioxidant protection in an oil blend. Citronella oil generates peroxides as it ages, which degrade carotenoids stored alongside it. Formulating them together shortens the useful life of both unless the packaging excludes air and light.
Tocopherols interrupt lipid peroxidation chains and are the default oxidation inhibitor for essential oils in a bottle. Citronella oil forms hydroperoxides on storage, and tocopherol slows the chain reaction that produces them. This protects the oil, not the user.
Ascorbate regenerates the tocopheroxyl radical back to tocopherol, which is why the two are paired in oxidation-sensitive formulations. In an oil-continuous product an ascorbyl ester is used instead, since ascorbic acid itself is water-soluble. The interaction is a stability one.
Nothing specific on file for Citronella Oil. Match the label to the daily amount above, and tell your doctor what you take.
Not medical advice. Show the label to your pharmacist.What Citronella Oil actually does.
Citronella oil is a volatile monoterpenoid mixture whose principal constituents are citronellal, geraniol and citronellol, with the ratio differing between the Ceylon type from Cymbopogon nardus and the Java type from Cymbopogon winterianus.
Being a mixture of small lipophilic terpenes, the oil is essentially insoluble in water and requires a fixed oil, an alcohol or an emulsifier to disperse in any aqueous system.
Citronellal is an aldehyde and oxidises on exposure to air and light, so an aged oil carries oxidation products that were not present in the fresh distillate.
Volatility is what makes the oil an aromatic material at all: its constituents have high enough vapour pressure to enter the air at room temperature, which also means an open container loses the lightest notes first.
Where Citronella Oil comes from.
Cut grass goes into a big steel vessel and steam is pushed through it. The steam picks up the aromatic oil, then gets cooled back into liquid, and the oil floats on top of the water so it can be drawn off. Two different grass species are used and they give slightly different smelling oils, so suppliers measure the main compounds to say which they have.
Made from a plant. What ends up in the capsule tracks the harvest, so batch testing and a stated marker matter more here than with a made molecule.
Tall tropical grass, either Cymbopogon nardus for the Ceylon type or Cymbopogon winterianus for the Java type. Leaves are cut several times a year and often wilted before distillation.
Chopped grass is packed into a still and steam is passed through it, carrying the volatile terpenes out with the vapour. Distillation time and pressure change which constituents come across.
The vapour is cooled in a condenser. The oil is lighter than water and separates on top of the condensate; the water layer left behind is the hydrosol.
Some supply is redistilled under vacuum to remove heavy residues and colour. Others are sold as the crude first distillate.
Batches are typically specified on citronellal and total geraniol content, since these move with grass variety, harvest timing and distillation conditions.
Sold as an amber to pale yellow liquid in air-excluding containers, as the aqueous hydrosol, or emulsified and spray-dried for dry blends.
The forms it comes in.
The essence, in one line each.
- Processing citronella distillation waste improved its measured nutritional quality and digestibility as a ruminant feed input, according to the authors' own conclusion.Animal study. Pamungkas et al., 2024 (Veterinary world). PMID 39185056 ↗
- A dietary plant essential oil blend shifted intestinal microflora composition and growth measures in laying hens; citronella is named among the plant oils rather than tested on its own.Animal study. Chen et al., 2025 (Poultry science). PMID 40652765 ↗
These are the studies our verdict leans on, chosen from the 2 we read for Citronella Oil. The full linked list is below.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.