Litsea Cubeba Face Serum: A 0.5% Starting Formula, Untested
If you make a litsea cubeba face oil, start at 0.5%, not 2%. Both sit inside the range in our own safety copy (0.5% to 2% in a carrier oil), but citral is a recognised skin sensitiser, a patch test is a screen, not a guarantee, and the face is where you will notice a reaction first. This post gives the arithmetic for a 10 ml and a 30 ml bottle, how to choose a carrier from what the published sources say, and the situations where you should not make it at all.
Litsea Cubeba Essential Oil
Our own Litsea Cubeba Essential Oil, in sizes from 0.5 oz to bulk.
From $12.99
Shop Now →Decide the strength first
Our oil is sold neat, so the dilution is yours to do. Our safety copy says to dilute to 0.5% to 2% in a carrier oil, patch test a small area first, start at the low end, keep the oil away from eyes, children and pets, and stop if irritation occurs. For a face product we recommend the bottom of that range. The reasoning: the European Commission's scientific committee (SCCS, 2012) lists citral among established contact allergens in humans, rated +++ in its summary table (SCCS, Table 7-1); DermNet describes the resulting contact dermatitis as a delayed hypersensitivity reaction and advises against applying neat oils to the skin, because that can lead to sensitisation (DermNet, 2020). Sensitisation builds with exposure, so a lower dose on a daily-use product is the more cautious choice. That is our recommendation, not a finding.
No IFRA limit can be calculated for our oil: we publish no IFRA certificate or allergen declaration, and the COA lists only appearance, smell, relative density 0.883, refractive index 1.483 and optical rotation +10.04. IFRA does carry a restriction standard for citral in its library (IFRA Standards library); a maker selling a product should read the current text and category definitions there, or ask a regulatory consultant. Our 0.5% to 2% copy is the only ceiling we state.
The arithmetic, for two bottle sizes
From the batch on our COA, 1 ml of oil weighs about 0.883 g. At about 20 drops per ml, one drop is about 0.05 ml or about 44 mg. Percentages below are by volume of the finished oil, which is close enough for a carrier of similar density.
| Bottle | Strength | Oil needed | Drops at 20/ml | About (mg) |
|---|---|---|---|---|
| 30 ml | 0.5% | 0.15 ml | 3 | 132 |
| 30 ml | 1% | 0.30 ml | 6 | 265 |
| 30 ml | 2% | 0.60 ml | 12 | 530 |
| 10 ml | 0.5% | 0.05 ml | 1 | 44 |
| 10 ml | 1% | 0.10 ml | 2 | 88 |
| 10 ml | 2% | 0.20 ml | 4 | 177 |
Check against our copy: 1 oz is about 591 drops, so 0.5% is about 3 drops and 2% about 12, which matches the 3 to 12 drops per ounce in our safety copy and the 30 ml rows.
Now the problem with the 10 ml row. Droppers vary. If your dropper delivers 15 drops per ml, a single drop is 0.067 ml and your 10 ml bottle is at 0.67%; at 30 drops per ml it is 0.33%. That is a spread of about a third either side of the target, from one drop. In the 30 ml bottle, three drops at those same two drop sizes give 0.67% and 0.33% as well, because the error scales the same way, but it is easier to weigh 132 mg on a 0.01 g kitchen scale across 30 g of carrier than 44 mg across 10 g. If you want repeatable batches, weigh the oil, and make the larger bottle so the number of drops is not one. Weighing needs a scale readable to at least 0.01 g, and the 0.5% target for 10 g is 0.05 g, which that scale cannot resolve well. That is a practical reason to prefer 30 ml.
Choosing the carrier from the sources
Jojoba is the usual carrier named for oily skin, and it is worth being exact about why and what is disputed. A 2021 review in Polymers (Gad et al., 2021) describes jojoba oil as about 98% wax, mainly wax esters of C20 and C22 monounsaturated acids and alcohols, not a triglyceride oil. It reports high oxidative stability for crude oil, attributed to natural tocopherols, and says bleaching or refining removes those antioxidants and sharply lowers stability. It reports human patch tests with no allergic reactions except in hyperallergic individuals. It does not give a comedogenicity rating, so the claim often repeated alongside jojoba (a low pore-clogging score) is not supported by that source.
Comedogenicity ratings are themselves disputed. Frank (1982, Journal of the American Academy of Dermatology, abstract only read by us) reviewed the rabbit-ear model proposed as a bioassay for comedogenic potential and reported "absence of correlation with experience in the human," concluding that its results are seriously limited for clinical use (Frank, 1982). We could not establish which published rating lists rely on that model, so treat any single number from any list as a rough prompt, not a measurement.
Practical consequences: buy the carrier from a craft or cosmetic supply shop (we do not sell carriers), ask for the INCI name and the data sheet, choose an unrefined or cold-pressed grade if you want the antioxidant content the review describes, and buy small quantities because the oil you add (citral-rich and, according to our own copy, quick to age) and the carrier both change over time. If you swap in another carrier, read that carrier's data sheet; we have not evaluated others here.
The formulation (we have not made this)
This is a formulation worked out from the arithmetic above and the sources cited, not a tested product. We have not made it, worn it, or measured anything about it. Treat the first batch as a trial.
- 30 ml jojoba (or another carrier you have checked), in a clean dark glass bottle.
- 3 drops of litsea cubeba oil at about 20 drops/ml (about 0.5%), or the equivalent 132 mg weighed.
- Cap, roll the bottle gently to mix, label with the date and the percentage.
Keep it water-free. By our reasoning, an oil-only mix has no water phase, whereas anything with water, hydrosol or gel needs a preservative system and an emulsifier chosen by a cosmetic chemist or a supply shop that sells tested bases; we do not cover that here. Before the first use on the face, do the patch test in skin basics on the diluted blend itself, not the neat oil, and wait the full period it describes.
When not to make it
- Near the eyes. Our copy says keep it away from eyes; apply well clear of the eye area.
- For acne. This is a scented face oil, not an acne product. The evidence picture, and why a dermatologist comes first, is in the acne post.
- If you react. Stop. DermNet says avoidance usually resolves the symptoms and that people who react to one oil often react to several; see a physician or dermatologist for a rash that persists.
- Pregnancy, children, prescription skin treatments. Ask a physician, pharmacist or dermatologist first. We do not state that the oil is suitable for any of these groups.
- Daytime sun exposure. Read what the phototoxicity research says before wearing it outdoors.
Store the finished bottle cool, dark and closed, the same way as the oil (storage guide), and discard it if the smell changes.
Litsea Cubeba Essential Oil
Litsea Cubeba Essential Oil from our own shop, in sizes from 0.5 oz to bulk.
From $12.99
Shop Now →Sources & Further Reading
- European Commission SCCS, 2012. Opinion on fragrance allergens, Table 7-1 (lay summary). ec.europa.eu/SCCS table 7-1
- DermNet, 2020. Allergic contact dermatitis to essential oils. dermnetnz.org/topics
- IFRA. IFRA Standards library (citral entry). ifrafragrance.org/safe-use/library
- Gad H.A. et al., 2021. Jojoba Oil: An Updated Comprehensive Review on Chemistry, Pharmaceutical Uses, and Toxicity, Polymers 13(11):1711. pmc.ncbi.nlm.nih.gov/PMC8197201
- Frank S.B., 1982. Is the rabbit ear model, in its present state, prophetic of acnegenicity? Journal of the American Academy of Dermatology 6(3):373-377. em-consulte.com/article/1148639