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Introduction ⬇

Camphor is one of several essential oils (volatile oils) derived from natural plant products that have been used for centuries as topical rubefacients for analgesic and antipruritic purposes (Table II-18). Camphor and other essential oils are found in several over-the-counter remedies. In addition, camphor is used for religious, spiritual, aromatic, folk medicinal, and insecticidal purposes, often in powder, tablet or cube form. Toxic effects primarily occur when essential oils are intentionally administered orally for purported therapeutic effects and in accidental pediatric ingestions.

TABLE II-18. ESSENTIAL OILSa
NameComments
Arnica OilContains sesquiterpene lactones. Vomiting, diarrhea, CNS depression, hypertension, bradycardia or tachycardia, and bleeding reported after acute ingestion. May cause allergic contact dermatitis.
Birch oilContains 98% methyl salicylate (equivalent to 1.4 g of aspirin per mL; see “Salicylates,”).
CamphorPediatric toxic dose 1 g (see text).
Cinnamon oilDermal: A potent sensitizing agent causing erythema, dermatitis, pruritus and stomatitis. Ingestion: oral irritation, diplopia, dizziness, vomiting, hypotension, tachycardia and CNS depression. Resolution within 5 hours. “Cinnamon challenge” (ingesting a spoonful of cinnamon powder without water) may result in coughing, choking, nasal and throat irritation, nausea, vomiting, and pneumonitis if aspirated.
Clove oilContains 80-90% eugenol. Toxic dose in children is 5 mL. Metabolic acidosis, CNS depression, seizures, coagulopathy, hypoglycaemia, and hepatotoxicity after acute ingestion. N-Acetylcysteine may be beneficial in preventing or treating the hepatotoxicity. Smoking clove cigarettes may cause irritant tracheobronchitis, hemoptysis.
Eucalyptus oilContains 70% eucalyptol. Toxic dose is 5-10 mL. Ingestion causes epigastric burning, vomiting, diarrhea, hypoventilation, tachycardia, hypotension, ataxia, seizures, or rapid CNS depression.
GuaiacolNontoxic.
Lavender oilMild headache, constipation, and reversible gynecomastia (in prepubertal boys) reported with chronic dermal application. CNS depression and confusion within 3 hours of ingestion in an 18-month-old male. Anticholinergic syndrome, supraventricular tachycardia after lavender stoechas tea ingestion.
Melaleuca oilTea tree oil. Toxic dose in children is 10 mL. Sedation, confusion, ataxia, and coma are reported after ingestion. Onset in 30-60 minutes. Contact dermatitis with dermal contact.
MentholAn alcohol derived from various mint oils. Ingestion may cause oral mucosal irritation, vomiting, tremor, ataxia, and CNS depression.
NutmegMyristica oil. Used as a hallucinogen and purported to have amphetamine-like effects; 2-4 tablespoons of ground nutmeg can cause psychogenic effects. Symptoms: abdominal pain, vomiting, lethargy, delirium, dizziness, agitation, hallucinations, seizures, miosis or mydriasis, tachycardia, and hypertension.
Pennyroyal oilModerate-to-severe toxicity with ingestion of more than 10 mL. Vomiting, abdominal cramping, syncope, coma, centrilobular hepatic necrosis, renal tubular degeneration, disseminated intravascular coagulation, multiple-organ failure, and death. N-Acetylcysteine may be effective in preventing hepatic necrosis.
Peppermint oilContains 50% menthol. Oral mucosal irritation, burning, vomiting and rarely mouth ulcers reported. Intravenous injection resulted in coma, cyanosis, pulmonary edema, and ARDS. Allergic contact dermatitis with dermal exposure. Nasal instillation in 2-month-old resulted in dyspnea, stridor, hyperextension, coma, and metabolic acidosis.
ThymolUsed as an antiseptic (see “Phenol,”). May cause allergic contact dermatitis.
Wintergreen oilContains methyl salicylate 98% (equivalent to 1.4 g of aspirin per mL; see “Salicylates,”).
Wormwood oilContains up to 70% thujone. Absinthe. Euphoria, vomiting, lethargy, confusion, agitation, hallucinations, seizures, rhabdomyolysis, renal failure, bradycardia, arrhythmias.

aInformation primarily derived from case reports often lacking detailed or documented laboratory confirmation.

Mechanism of Toxicity ⬆ ⬇

  1. After topical application, essential oils produce dermal hyperemia followed by a feeling of comfort, but if ingested, they can cause systemic toxicity. Most essential oils cause CNS stimulation or depression. Camphor is a CNS stimulant that causes seizures soon after ingestion. The underlying mechanism is unknown. Camphor is absorbed rapidly from the GI tract and metabolized by the liver. It is not known whether metabolites contribute to toxicity.
  2. Overdose during pregnancy. Camphor crosses the placenta, and there are case reports of overdose during pregnancy. One infant died 30 minutes after delivery but labor was complicated by pre-eclampsia, premature placental separation and breech presentation. Laboratory confirmation of camphor in the infant was documented. Two additional cases involved maternal seizures but with delivery of health babies.
  3. Pharmacokinetics. Well absorbed after inhalation, ingestion, or dermal application. Following ingestion, seizures may occur within 20-60 minutes. Onset of serious toxicity in asymptomatic patients is unlikely after 4 hours. The volume of distribution is 2-4 L/kg. The half-life is 1.5-2.7 hours. Camphor is primarily metabolized by the liver and eliminated in the urine as the glucuronide form.

Toxic Dose ⬆ ⬇

Serious poisonings and death have occurred in infants and children after ingestion of as little as 0.7-1 g of camphor. This is equivalent to less than a teaspoon of camphorated oil (20%). Recovery after ingestion of 42 g in an adult has been reported. The concentrations of other essential oils range from 1% to 20%; doses of 5-15 mL are considered potentially toxic. Doses <30 mg/kg are unlikely to result in serious toxicity.

Clinical Presentation ⬆ ⬇

(See also Table II-18)

  1. Acute manifestations including burning in the mouth and throat occurs immediately, followed by nausea, vomiting, and abdominal discomfort. Ataxia, drowsiness, dizziness, confusion, hallucinations, restlessness, seizures, delirium, muscle twitching, and coma may occur. Aspiration may result in pneumonitis. Death is rare and may result from respiratory arrest or complications of status epilepticus.
  2. Chronic camphor exposure has resulted in myocarditis, granulomatous hepatitis, and death.
  3. Dermal exposure may result in flushing and allergic reactions. Extensive pediatric dermal exposure or application of powdered camphor in oil has resulted in ataxia and seizures.
  4. Smoking (eg, clove cigarettes) or inhaling essential oils may cause tracheobronchitis.
  5. IV injection (eg, peppermint oil) can cause pulmonary edema and acute respiratory distress syndrome (ARDS).

Diagnosis ⬆ ⬇

Usually is based on a history of exposure. The pungent odor of camphor and other volatile oils is usually apparent.

  1. Specific levels are not available.
  2. Other useful laboratory studies include electrolytes, glucose, liver aminotransferases, and arterial blood gases (if the patient is comatose or in status epilepticus).

Treatment ⬆

  1. Emergency and supportive measures
    1. Maintain an open airway and assist ventilation if necessary.
    2. Treat seizures and coma if they occur.
  2. Specific drugs and antidotes. There are no specific antidotes for camphor. N-acetylcysteine may be effective for preventing hepatic injury after pennyroyal and clove oil ingestion. Naloxone may be effective for reversing the central nervous system and respiratory depression from eucalyptus oil ingestion.
  3. Decontamination. Wash exposed skin thoroughly with soap and water. Administer activated charcoal orally if conditions are appropriate (see Table I-37).
  4. Enhanced elimination. The volumes of distribution of camphor and other essential oils are extremely large, and it is unlikely that any enhanced removal procedure will remove significant amounts of camphor.