Cedar oil is an essential oil derived from the wood, roots, or foliage of various coniferous trees, often sought for its aromatic and pest-repelling properties. Its toxicity depends highly on how it is sourced, its concentration, and the method of exposure. While some forms of cedar oil have low acute toxicity, the concentrated nature of all essential oils necessitates careful handling around both people and animals.
Factors Determining Toxicity
The chemical makeup and safety of cedar oil vary significantly based on the plant species from which it is extracted. “Cedar oil” is a general term referring to oils from true cedars (Cedrus species), junipers (Juniperus species) like Virginia or Texas cedarwood, or arborvitae (Thuja species). Oils from Juniperus virginiana and Juniperus ashei contain sesquiterpene hydrocarbons like cedrol and alpha-cedrene, associated with low toxicity. Conversely, oils from species like Western Red Cedar (Thuja plicata) contain high levels of thujone, a neurotoxic compound contraindicated for internal use.
The concentration of the oil is another major determinant of risk, as undiluted essential oils are powerful chemical solvents. Concentrated oil presents a much higher risk for immediate irritation or systemic toxicity than a heavily diluted product. The route of exposure also dictates the severity of a reaction, with ingestion and inhalation of concentrated vapor carrying greater risks than topical application. The US Environmental Protection Agency (EPA) generally considers the risk of cedarwood oil negligible for humans when used according to label instructions.
Specific Risks to Humans
When concentrated cedar oil is applied directly to the skin, it can easily cause irritation, redness, and contact dermatitis due to its solvent properties. Even in diluted forms, some individuals may develop skin sensitization, an allergic reaction that manifests after repeated exposure. Although Virginia cedarwood oil is generally not a sensitizer when diluted, a patch test should always be performed.
Ingestion of cedar oil is dangerous. Swallowing the oil can lead to gastrointestinal distress, including nausea, vomiting, and diarrhea. There is also a risk of chemical pneumonitis if the oil is aspirated into the lungs. In large amounts, the terpenes can cause central nervous system depression, leading to symptoms like giddiness, dizziness, or slowed reaction time, and in severe cases, respiratory depression.
Certain human populations are more susceptible to adverse effects, especially from aromatic exposure via diffusers. Infants, young children, and pregnant women should use essential oils with greater caution, often requiring a lower maximum topical dilution of 1% instead of the standard 2-3%. Individuals with pre-existing respiratory conditions, such as asthma, may experience airway irritation or exacerbation of symptoms from inhaling volatile compounds.
Specific Risks to Household Pets
Essential oils pose a greater danger to household pets, particularly cats, compared to humans. Cats are uniquely vulnerable to toxicity because their livers are deficient in the specific enzyme pathway known as glucuronyl transferase. This enzyme is necessary for the efficient metabolism and elimination of many compounds found in essential oils, including phenols and terpenes. The lack of this detoxification mechanism means the oil’s components build up to toxic levels, leading to systemic poisoning and potential liver or kidney failure.
Even passive exposure, such as inhaling diffused cedar oil, can be harmful to a cat over time. The oil can be absorbed through the lungs or skin, and cats are also at high risk because they ingest the oil when grooming their fur. Dogs are generally less sensitive as they possess the necessary metabolic enzymes, but they can still suffer topical burns if concentrated oil is applied to their skin. Dogs are also susceptible to toxicosis if they ingest the oil or are confined in areas with high concentrations of diffused oil.
Signs of essential oil poisoning in pets can develop rapidly, often within minutes to a few hours of exposure. Common symptoms include:
- Lethargy
- Drooling
- Vomiting
- Uncoordinated movements (ataxia)
- Difficulty breathing
Other severe indicators of systemic toxicity include tremors, seizures, and collapse, which require immediate veterinary intervention.
Safe Usage and Emergency Response
The proper use of cedar oil relies on dilution and secure storage to prevent accidental exposure. For topical human use, essential oils must be blended into a carrier oil, with a maximum concentration of 2% generally recommended for adults. All essential oils should be stored in their original, tightly closed containers in a location inaccessible to children and pets.
If cedar oil is ingested by a human, contact a certified poison control center immediately; do not induce vomiting unless instructed by a medical professional. If concentrated oil contacts the skin, the area should be thoroughly washed with soap and water to remove the substance. Adequate ventilation should be maintained when using cedar oil in diffusers to minimize inhalation risk for all household members.
If a pet is suspected of exposure, immediately remove the animal from the source and contact a veterinarian or a pet poison helpline. Do not attempt to induce vomiting unless advised by an animal health professional. For dermal exposure, gently wash the affected area with a mild dish soap and rinse well before seeking medical advice.