1,8-Cineole, also called eucalyptol, is one of the best-studied aroma constituents in the AromaForge archive and a defining compound in eucalyptus, rosemary cineole, niaouli cineole, cardamom, bay leaf, and other camphoraceous oils. Compared with many terpenes, it has a substantial evidence base spanning reference identity data, human pharmacokinetic work, randomized respiratory trials, and mechanistic studies on inflammatory signaling and mucus-related pathways. That said, most benefit-forward literature is concentrated in respiratory contexts and should not be generalized into broad medical claims, while safety literature still supports extra caution around concentrated eucalyptus-rich materials in young children.
Chemical identity and composition
PubChem identifies 1,8-cineole as CID 2758 with formula C10H18O and IUPAC name 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane. Synonym data confirm the common names eucalyptol, cineole, cajeputol, and 1,8-epoxy-p-menthane. Across the archive, this constituent appears under several naming variants but consistently represents the same oxide monoterpene that drives the cool eucalyptus-like profile of cineole-rich oils.
Aroma and practical use
- Use the recorded eucalyptus-like, fresh, camphoraceous, cooling, penetrating 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 1996 human pharmacokinetic study reported that inhaled 1,8-cineole was well absorbed from breathing air, reached peak plasma concentration after about 18 minutes, and showed biphasic elimination with a mean terminal half-life of 104.6 minutes.
A 1996 human pharmacokinetic study reported that inhaled 1,8-cineole was well absorbed from breathing air, reached peak plasma concentration after about 18 minutes, and showed biphasic elimination with a mean terminal half-life of 104.6 minutes.
Apply this finding only to the studied preparation, participants, route and outcome. It does not establish the same result for a custom oil blend.
A 2003 double-blind placebo-controlled asthma trial found that 200 mg 1,8-cineole taken three times daily for 12 weeks had a significant steroid-sparing effect in steroid-dependent bronchial asthma compared with placebo.
A 2003 double-blind placebo-controlled asthma trial found that 200 mg 1,8-cineole taken three times daily for 12 weeks had a significant steroid-sparing effect in steroid-dependent bronchial asthma compared with placebo.
Apply this finding only to the studied preparation, participants, route and outcome. It does not establish the same result for a custom oil blend.
A 2009 placebo-controlled double-blind COPD study in 242 patients reported lower exacerbation frequency, severity, and duration with cineole, together with improved lung function, dyspnea, and quality of life relative to placebo.
A 2009 placebo-controlled double-blind COPD study in 242 patients reported lower exacerbation frequency, severity, and duration with cineole, together with improved lung function, dyspnea, and quality of life relative to placebo.
Apply this finding only to the studied preparation, participants, route and outcome. It does not establish the same result for a custom oil blend.
A 2016 cell-plus-mouse asthma study found that 1,8-cineole reduced Der p-induced IL-8, IL-6, GM-CSF, TLR4 expression, p38 MAPK phosphorylation, Akt phosphorylation, eosinophilic airway inflammation, and airway hyper-responsiveness.
A 2016 cell-plus-mouse asthma study found that 1,8-cineole reduced Der p-induced IL-8, IL-6, GM-CSF, TLR4 expression, p38 MAPK phosphorylation, Akt phosphorylation, eosinophilic airway inflammation, and airway hyper-responsiveness.
This experimental finding does not establish benefit, dose or safety in people using this blend.
Use concerns and concentration limits
Sensitization concernNot assessed
Not assessed in the available record.
Phototoxicity concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Oxidation concernNot assessed
Not assessed in the available record.
Penetration enhancementNot assessed
Not assessed in the available record.
A recorded constituent reference, not a recommended oil dilution. Product category, source applicability and all contributing oils must be checked before use.
unverified reference · No source provenance attachedA 2021 prospective pediatric study documented eucalyptus-oil-induced seizures in 17 children after oral exposure, with a median 20-minute interval to seizure onset; concentrated eucalyptus-oil exposure is therefore not trivial in children.
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.
The pediatric seizure study evaluated whole eucalyptus oil exposure rather than isolated 1,8-cineole dosing, so it is best used as constituent-relevant cautionary context rather than as a pure-molecule dose threshold.
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.
Most efficacy literature for isolated 1,8-cineole centers on respiratory indications; those results should not be generalized into broad therapeutic claims for all aroma use cases.
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.
alpha-PineneAmplification 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.
in vitro · effect
No source citation attached.
Read alpha-Pinene report →LimoneneOpposing 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.
in vitro · effect
No source citation attached.
Read Limonene report →alpha-TerpineolOpposing 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.
animal · effect
No source citation attached.
Read alpha-Terpineol report →Terpinen-4-olAmplification 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.
in vitro · effect
No source citation attached.
Read Terpinen-4-ol report →CarvacrolAmplification 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.
in vitro · effect
No source citation attached.
Read Carvacrol report →beta-PineneAmplification 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.
in vitro · effect
No source citation attached.
Read beta-Pinene report →AromadendreneAmplification 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.
in vitro · effect
No source citation attached.
Read Aromadendrene report →CamphorAmplification 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.
in vitro · effect
No source citation attached.
Read Camphor report →alpha-PineneAmplification 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.
in vitro · antioxidant
No source citation attached.
Read alpha-Pinene report →CarvacrolAmplification 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.
in vitro · whole_oil
No source citation attached.
Read Carvacrol report →alpha-TerpineolAmplification 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.
in vitro · whole_oil
No source citation attached.
Read alpha-Terpineol report →LinaloolAmplification 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.
in vitro · effect
No source citation attached.
Read Linalool report →CamphorAmplification 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.
animal · effect
No source citation attached.
Read Camphor report →(E)-CaryophylleneAmplification 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.
animal · effect
No source citation attached.
Read (E)-Caryophyllene report →alpha-TerpineneAmplification 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.
in vitro mechanistic · antioxidant
No source citation attached.
Read alpha-Terpinene report →MentholAmplification 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.
clinical · whole_oil
No source citation attached.
Read Menthol report →How the effects were investigated
suppression_of_inflammatory_cytokines_and_mediator_signaling
Review and experimental literature consistently describe 1,8-cineole as reducing inflammatory mediator production rather than acting only as a simple aroma or mucus-thinning agent.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
tlr4_p38_mapk_and_akt_pathway_modulation
In HDM-stimulated bronchial epithelial cells, 1,8-cineole reduced intracellular TLR4 expression and phosphorylation of p38 MAPK and Akt while lowering cytokine output.
This experimental finding does not establish benefit, dose or safety in people using this blend.
systemic_absorption_after_inhalation
Human pharmacokinetic work shows that inhaled 1,8-cineole is absorbed into blood within minutes, supporting the plausibility of systemic effects after inhalation exposure.
Apply this finding only to the studied preparation, participants, route and outcome. It does not establish the same result for a custom oil blend.
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 (7)
- Although 1,8-cineole has more human evidence than most archive constituents, much of the literature remains respiratory-specific rather than generalizable to other wellness contexts.
- The seizure caution literature often evaluates eucalyptus oil exposure rather than isolated 1,8-cineole alone, which limits molecule-specific dose interpretation.
- A single unified archive naming convention for this constituent is still absent across oil files, where several id variants are currently in use.
- A 2024 RIFM update reports a NESIL of 7000 ug/cm2 for the skin sensitization endpoint; this pass could not retrieve the underlying PDF's full endpoint table, so the 20% dermal ceiling is corroborated via a secondary summary (citing Tisserand & Young) rather than direct access to the primary RIFM/IFRA text.
- The numeric dermal reference lacks source provenance; a verified flag alone is insufficient.
- 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.