Camphor

Aroma and sensory profile

Camphor is the reference smell for its own descriptor. Fragrance references type it camphoreous and describe the racemate at 10 percent simply as camphoreous, with a camphoraceous, pine flavor [1]; chemical handbooks compiled by PubChem call it a fragrant, penetrating odor and a penetrating aromatic odor [4]. It is cooling in the nose the way menthol is cooling in the mouth, sharp enough that it reads as medicinal at almost any concentration. It arrives as white, waxy, translucent crystals that sublime at room temperature.

The molecule is a bicyclic monoterpene ketone with two stereocenters and it is chiral, and the enantiomers differ. (+)-camphor, the form the camphor tree makes, is described at 10 percent as camphor, minty, phenolic, herbal, and woody, or camphoreous, medicinal, and mentholic with a cooling green nuance, with a flavor at 20 parts per million of medicinal, camphoreous, mentholic, and woody [2]. (−)-camphor, found in Artemisia, feverfew, and sage, is described only as camphor [3]. The (+) form is the sharper, mintier, more medicinal of the two.

Effects and research

Camphor is one of the few terpenes with a human evidence base, and much of it is toxicology. A 2026 review catalogued insecticidal, antimicrobial, antiviral, antinociceptive, anticancer, and antitussive findings and its long use in topical remedies [5]. Its sensory action is well characterized: camphor activates and modulates the warmth-sensing channel TRPV3, and mutation of a single pore-region cysteine abolishes the response [9], which is the mechanism behind the warming-then-numbing feel of a camphor rub.

The human data on ingestion are unambiguous. An evidence-based guideline covering roughly 10,000 exposures a year concluded that anyone who has swallowed more than 30 milligrams per kilogram, or who shows moderate to severe symptoms, needs an emergency department [6]. In a seven-year series of 30 severe poisonings, mostly young men who had ingested 1.5 to 15 grams, tonic-clonic seizures occurred in 40 percent, and all survived with supportive care [7]. A cluster of three young children seized after exposure to imported camphor sold for spiritual and pest-control use [8]. Camphor's traditional oral use is also the subject of a meta-analysis: in four randomized trials of 221 adults, a fixed hawthorn-camphor combination significantly raised systolic and diastolic blood pressure against placebo [11].

Inhaled, the picture is gentler. In mice, (+)-camphor vapor at 4 × 10⁻⁴ milligrams per cage reduced spontaneous motor activity in a dose-dependent, sedative manner alongside menthol and geraniol [10].

Natural sources

Camphor is the camphor tree's namesake and a common Artemisia terpene. Fenaroli's handbook records it as obtained from Cinnamomum camphora, native to China, Taiwan, and Japan, whose leaf, wood, and stumpwood oils contain free crystalline camphor, with some varieties reaching 42 percent, and the USDA database detects it across the leaves, roots, stems, flowers, fruits, and rhizomes of numerous species [4]. Fragrance databases log it at 57.5 percent in Artemisia diffusa oil, 36.9 percent in Achillea tenuifolia flower oil, 15.7 percent in Artemisia deserti, and 10.3 percent in Moroccan armoise, with traces in anise, basil, and cardamom [1]. The (+) form is recorded in camphor oil, basil, bay laurel, and cardamom [2], the (−) form in armoise, feverfew, and sage [3]. Rosemary carries it as a defining note. In cannabis camphor is a trace terpenoid, reported occasionally and usually below detection.

Boiling point and vaporization

PubChem compiles camphor's boiling point as 209 °C from the Merck Index, 204 °C from the International Chemical Safety Cards and other safety databases, and 399 °F from the US Coast Guard, with the CRC Handbook noting that it sublimes at its boiling point; its melting point is 174 to 180 °C [4]. Fragrance references give 204 to 205 °C at 760 mmHg [1]. This profile keeps 209 °C (408 °F), which matches what the site already listed. The number matters less for camphor than for any other terpene here, because camphor sublimes freely at room temperature: it passes from crystal to vapor without melting. It is a flammable solid, and 98 percent of European classification notifications say so [4]. No thermal degradation study of camphor was found.

Safety and regulation

Camphor is listed by the US Food and Drug Administration as a permitted synthetic flavoring substance at 21 CFR 172.515, as "d-Camphor" [12], and is a regulated active ingredient in over-the-counter topical analgesic and cough products. No cancer classification applies.

Its hazard is systemic, not dermal. Under Europe's classification inventory, 98 percent of notifications flag it as a flammable solid, 94 percent as harmful if inhaled, 73 percent as capable of causing organ damage, and 15 to 20 percent as harmful if swallowed, with skin irritation in about 10 percent and no sensitization code above threshold [4]. The clinical threshold is 30 milligrams per kilogram swallowed, above which seizures are the characteristic sign [6][7]. The pediatric cluster shows the route: camphor sold as blocks or tablets for religious, cold-remedy, or pest-control use, within reach of toddlers [8]. On skin camphor is a mild irritant and not a recognized allergen.

Industries and uses

Fragrance: camphor supplies a sharp camphoraceous accent in medicinal, herbal, and fougère accords and is stocked as racemic and (+) grades [1][2]. Culinary: it holds FDA flavoring status and appears at trace levels in spice and herbal flavors [1][12]. Aromatherapy: camphor, rosemary, and Artemisia oils are its carriers; the inhalation sedation data and the ingestion toxicology are the two poles of its caution [6][10]. Pharmaceuticals: it is an active ingredient in chest rubs and topical analgesics acting through TRPV3, and the hawthorn-camphor combination has randomized trial evidence for raising blood pressure [9][11].