Lemongrass is one of the most popular "clean" candle scents, and makers often choose the essential oil because it feels simpler than a fragrance oil. Then the label calculation comes back with an exclamation mark and H317, while their lemon-scented candle at the same load has none. The reason is one molecule: citral. Here's what it is, why lemongrass is so full of it, and what that does to your label.

What citral is

Citral is the name for two closely related aldehydes, geranial and neral, the E and Z forms of the same molecule (3,7-dimethyl-2,6-octadienal, CAS 5392-40-5, EC 226-394-6). Together they give the sharp, sherbet-like lemon note most people recognise instantly. On a safety data sheet you may see citral listed as one line, or geranial and neral listed separately. For classification you add them together.

Why lemongrass smells more lemon than lemon

It sounds backwards, but lemon peel oil contains very little citral. Cold-pressed lemon oil is mostly limonene, typically 60 to 80%, and limonene on its own smells faintly of orange peel rather than lemon. The recognisable lemon signature comes from a few percent of citral, commonly around 2 to 3% in the oil.

A handful of plants make citral their main product instead:

  • Lemongrass (Cymbopogon species): typically about 65 to 85% citral.
  • Litsea cubeba (may chang): roughly 70 to 85%.
  • Lemon myrtle (Backhousia citriodora): often above 90%.

So lemongrass hits the lemon note far harder than lemon does, with a grassy, slightly green edge and none of the juicy peel. Chemically, a lemongrass candle is mostly a citral candle. As we explain in why essential oils still carry hazard labels, "natural" doesn't change how a substance is classified.

How citral is classified

Citral has a harmonised classification in CLP Annex VI (index 605-019-00-3). We checked ECHA's C&L Inventory on 29 September 2026:

  • Skin Sens. 1, H317 "May cause an allergic skin reaction".
  • Skin Irrit. 2, H315 "Causes skin irritation".
  • No specific concentration limit and no sub-category 1A or 1B, so the generic limits apply.

Some supplier SDSs also list Eye Irrit. 2 for citral. That comes from industry self-classifications, not the harmonised entry. Citral is also one of the fragrance allergens EU cosmetics law has required naming on labels since 2005, which is why you'll see it on the EUH208 "Contains…" line of many candles.

For a candle, two rules matter:

  • H317 applies when citral reaches 1% in the finished candle. From 0.1% up to that, it must be named on the EUH208 line instead.
  • H315 only applies to the candle when all its Skin Irrit. 2 ingredients together reach 10%. At normal fragrance loads that almost never happens.

A worked example: lemongrass vs "lemon" at 8%

Take two candles, same wax, same 8% fragrance load.

Candle A: lemongrass essential oil whose SDS lists 75% citral.

  • Citral in the candle: 8% × 75% = 6%. That's six times the 1% limit, so the candle is Skin Sens. 1, H317, with the exclamation mark pictogram and the signal word "Warning", plus the matching precautionary statements.
  • H315 doesn't follow. Even if the whole oil counted as a skin irritant, it's only 8% of the candle, under the 10% line.
  • How low would you need to go to lose H317? Citral must stay under 1%, so the load would have to fall below about 1.3%. That isn't a scented candle any more. A properly scented lemongrass candle carries H317.

Candle B: a hypothetical "lemon" fragrance oil whose SDS lists 10% limonene and 2.5% citral, with the rest made of unclassified materials.

  • Citral: 8% × 2.5% = 0.2%. Over 0.1% but under 1%, so no pictogram. It goes on the EUH208 line.
  • Limonene: 8% × 10% = 0.8%. Limonene is Skin Sens. 1B with the same 1% limit, so it also lands on the EUH208 line.
  • Result: no pictogram, just "Contains citral, limonene. May produce an allergic reaction."

Don't read this as "lemon is always safe". A lemon blend built on lemon peel oil can be 60% limonene or more, and at 8% that's close to 5% limonene: H317 again, just from a different molecule. We cover that case in limonene in citrus candles. The point is that the label follows the substances and their concentration, not the scent name.

What IFRA says

Citral has an IFRA Standard (a restriction, published with Amendment 49 and carried into the 51st Amendment) driven by dermal sensitisation and systemic toxicity. It caps citral in skin products at fractions of a percent, but for Category 12, which covers candles, wax melts and reed diffusers, the entry reads "No Restriction". Sprayed room fragrances fall in Category 10B, where the cap is 4.2%. See IFRA categories explained for how categories work. So IFRA won't stop a strong lemongrass candle. CLP still puts the H317 on it.

A note on citronella candles

Citronella oil comes from related grasses (Cymbopogon nardus and C. winterianus), but its scent is built mainly on citronellal and geraniol, with little citral. Geraniol has its own harmonised Skin Sens. 1 classification. Citronellal has no harmonised entry, but most industry notifications to ECHA classify it as Skin Irrit. 2, Eye Irrit. 2 and Skin Sens. 1B. Expect a citronella candle to need H317 too.

The bigger trap is the claim. Under the EU Biocidal Products Regulation (Regulation (EU) No 528/2012), a product sold to repel insects is a biocidal product (product-type 19, repellents and attractants). It can only be sold with that claim if its active substance is approved or still under review for that use and the product itself is authorised, or allowed under national transitional rules while the review runs. Selling a citronella-scented candle is a fragrance product. Writing "keeps mosquitoes away" on it turns it into a biocide.

What to do with this

  • Plan for H317 on any lemongrass, litsea or lemon myrtle candle. Put the exclamation mark and "Warning" on the label from the start.
  • Add geranial and neral together when an SDS lists them separately.
  • Don't assume a lemon candle is label-free. Check its limonene and citral at your actual load.
  • Keep insect claims off citronella candles unless the product is authorised as a biocide.

Molekule reads citral, geranial, neral and limonene from your fragrance's safety data sheet, checks each against ECHA's live classifications and works out, at your load, whether they trigger H317 or belong on the EUH208 line. Check your lemongrass candle's label in Molekule.