CONSTITUENT REPORT
Stearic acid
Stearic acid is a common C18 saturated fatty acid found in many fixed oils and butters, and in the AromaForge archive it appears mainly as a compositional lipid marker rather than a volatile fragrance-active. The evidence base is strong for identity, occurrence, cosmetic-use history, and skin-barrier formulation context. Direct wellness-style evidence for isolated stearic acid is much less relevant than its role as a structural fatty acid and widely reviewed cosmetic ingredient, so archive copy should keep the emphasis on chemistry, formulation, and source-grounded skin-barrier context rather than medical claims.
Chemical identity and composition
PubChem identifies stearic acid as CID 5281 with formula C18H36O2, IUPAC name octadecanoic acid, and InChIKey QIQXTHQIDYTFRH-UHFFFAOYSA-N. In the local archive it appears repeatedly in carrier and seed oils, including pumpkin seed oil at 5.4%, moringa oil at a cited 2.0-8.0% range, and carrot seed oil at 2.41%. Unlike volatile terpenes, stearic acid is primarily a fixed-oil fatty-acid component used analytically and in formulation science.
Aroma and practical use
- Use the recorded waxy, fatty, soapy descriptors to explore a blend's scent character; perceived strength also depends on the other ingredients.
- Read the route, preparation and experimental context before using a study finding to choose an oil.
Reported benefits and effects
Findings retain their study context. An animal or laboratory result describes that experiment.
A 2010 human cleanser study detected deuterated stearic acid in all 10 consecutive stratum-corneum tape strips after use of a mild body-wash formulation and estimated 0.33 microg/cm2 delivered after five washes.
A 2010 human cleanser study detected deuterated stearic acid in all 10 consecutive stratum-corneum tape strips after use of a mild body-wash formulation and estimated 0.33 microg/cm2 delivered after five washes.
Apply this finding only to the studied preparation, participants, route and outcome. It does not establish the same result for a custom oil blend.
The same 2010 study concluded that delivered stearic acid was most likely incorporated into the corneum lipid phase, supporting a formulation-level barrier-context role rather than a drug-like mechanism claim.
The same 2010 study concluded that delivered stearic acid was most likely incorporated into the corneum lipid phase, supporting a formulation-level barrier-context role rather than a drug-like mechanism claim.
Apply this finding only to the studied preparation, participants, route and outcome. It does not establish the same result for a custom oil blend.
The 2019 Cosmetic Ingredient Review safety assessment of fatty acids and fatty acid salts states that the panel assessed 102 ingredients, including stearic acid, as safe in the present practices of use and concentration when formulated to be non-irritating and non-sensitizing.
The 2019 Cosmetic Ingredient Review safety assessment of fatty acids and fatty acid salts states that the panel assessed 102 ingredients, including stearic acid, as safe in the present practices of use and concentration when formulated to be non-irritating and non-sensitizing.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
Use concerns and concentration limits
Sensitization concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Phototoxicity concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Oxidation concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Penetration enhancementNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
A recorded constituent reference, not a recommended oil dilution. Product category, source applicability and all contributing oils must be checked before use.
recorded reference · CIR Safety Assessment of Fatty Acids & Fatty Acid Salts as Used in Cosmetics (cir-safety.org/sites/default/files/facids042019finalrep.pdf, 2019): cosmetic formulations containing stearic acid at concentrations up to 13% were not primary or cumulative irritants nor sensitizers.Current public cosmetic-safety review context is materially stronger than constituent-specific efficacy literature for isolated stearic acid.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
No direct public citation is attached to this entry.
The Cosmetic Ingredient Review safety conclusion is conditional on finished products being formulated to be non-irritating and non-sensitizing, so it should not be treated as a blanket claim for all concentrations or all uses.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
No direct public citation is attached to this entry.
No aroma-industry style constituent-specific dermal maximum for isolated stearic acid was verified in this pass.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
No direct public citation is attached to this entry.
Constituents it may interact with
These are research candidates recorded in the interaction matrix. They do not add a proven-amplification bonus to the score.
Linoleic acidAmplification candidate
Candidate in the research matrix. A coefficient alone does not establish amplification at the dose, route or goal of your blend; no proven amplification is inferred from this row.
food chemistry · antioxidant
No source citation attached.
Read Linoleic acid report →How the effects were investigated
stratum corneum lipid phase incorporation
A human cleansing study using deuterated stearic acid reported delivery into multiple stratum-corneum layers and concluded that the fatty acid was most likely incorporated into the corneum lipid phase.
Apply this finding only to the studied preparation, participants, route and outcome. It does not establish the same result for a custom oil blend.
No direct public citation is attached to this entry.
What this report cannot establish
- A reported constituent percentage does not establish an effective human therapeutic dose or the amount absorbed into the body.
- The presence of a constituent does not guarantee a clinical benefit, rash treatment or sleep improvement from a custom blend.
- An unflagged concern or missing use limit does not establish safety for ingestion, inhalation, skin exposure or a particular person.
- A candidate constituent interaction does not establish that two oils amplify one another at the selected proportions.
- Constituent descriptors alone do not establish a precise top, heart or base lifetime in a finished blend.
Known data gaps (6)
- No constituent-specific human clinical efficacy literature for isolated stearic acid was targeted or verified beyond formulation-context studies.
- No IFRA-style essential-oil dermal maximum or phototoxicity limit specific to isolated stearic acid was located in this pass; the dermal_limit_pct below reflects the CIR cosmetic-safety concentration finding rather than an IFRA leave-on limit.
- Most archive-relevant evidence concerns occurrence and cosmetic safety review rather than standalone bioactivity.
- The previous dermal_limit_pct value of 25 had no locatable citation; corrected to 13% on 2026-07-13 based on the CIR fatty-acids safety assessment finding that cosmetic formulations containing stearic acid up to 13% were not primary or cumulative irritants nor sensitizers.
- Some findings do not record an explicit exposure route; consult the linked study before applying them to a use.
- Interaction candidates lack an attached source citation and remain unqualified.