Camphor Hepatotoxicity

Aliye Uc, MD, Warren P. Bishop, MD, and Kathleen D. Sanders, MD, Department of Pediatrics, University of Iowa College of Medicine, Iowa City, Iowa

South Med J. 2000;93(6) 

In This Article


Camphor is a pleasant-smelling cyclic terpene[1,2] that is a constituent of several medications (Table 2). When rubbed on the skin, camphor is rubefacient, but if not vigorously applied it creates a sense of coolness. The respiratory tract is particularly sensitive to its action, which is thought to be due to stimulation of nerve endings sensitive to cold. Camphor causes local irritation on the skin that may block pain by counterirritation at the same segmental central nervous system level.[2] Camphor is marketed in over-the-counter cold remedies for its mild local anesthetic and rubefacient effects.

Camphor can easily cross the skin, the mucous membranes, and the placental barrier, and it can cause significant hepatoneurotoxicity.[1,2,4,6,8,9,10] Ingestion of even small doses of camphor can cause fatal poisoning in small children.[3] It produces gastrointestinal and central nervous system irritation after toxic ingestion. Nausea and vomiting followed by agitation and seizures are common. Hepatotoxicity may range anywhere from a mild elevation of liver function test values to hepatic encephalopathy.[6,8,9] Our patient did not manifest any neurologic or gastrointestinal side effects typical of camphor poisoning. She had no gastrointestinal side effects of camphor, probably because the medication was applied topically, not taken orally. Gastrointestinal side effects have not been observed in children exposed to camphor through the skin or by inhalation.[4,5] Hepatotoxicity due to skin exposure and inhalation might be expected, but it has never been reported. In our patient, the timing of application of the cold remedy, the rapid normalization of the liver enzymes after the use of camphor was discontinued, and the absence of a viral, metabolic, or anatomic etiology suggest camphor poisoning. Hepatitis due to an unknown virus cannot be completely ruled out, but it is probably unlikely in view of the high aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio and rapid normalization of the liver enzymes. This patient also had a high serum LDH that paralleled the transaminases. A high serum LDH level and a high AST-ALT ratio have been observed in previous reports of camphor poisoning.[8,11] These laboratory findings may suggest hemolysis or more generalized tissue damage due to camphor toxicity.

It is hard to estimate the amount of camphor exposure in this infant, because the remedy was applied to the skin. Nevertheless, in a small, malnourished infant, the absorption through the skin can be substantial. Camphor is metabolized in the liver and is excreted as an inactive glucuronide compound in the urine.[1] Even small amounts of camphor can produce significant toxicity in infants because of their immature hepatic detoxification mechanisms.[12]

There is no specific diagnostic study or antidote for camphor poisoning.[1] The treatment usually includes gastrointestinal decontamination (ipecac-induced emesis, gastric lavage, and activated charcoal) and supportive treatment. One adult patient was successfully treated with lipid dialysis.[11] If the camphor toxicity is due to skin exposure or inhalation, application should be stopped immediately, clothes should be removed, and the environment should be cleaned.[5]

The majority of cases reported in the literature have been caused by accidental ingestion of camphorated oil (20% camphor), which is no longer available. Since Vicks VapoRub contains only 4.8% camphor, large amounts are needed to cause toxicity. Fatal cases are no longer seen, probably because of lowered camphor concentration in cold remedies,[1] but toxicity continues to be a problem. Other ingredients of Vicks VapoRub (menthol 2.6% and eucalyptus oil 1.2%) are not known to be hepatotoxic.

Since most of the cases reported in the literature were due to accidental ingestion, mild hepatoneurotoxicity with routine usage can be common and may remain silent. Hepatotoxicity was discovered in this case fortuitously while the infant was being monitored for refeeding syndrome. Refeeding syndrome was ruled out by the absence of the typical biochemical findings (hypophosphatemia, hypocalcemia, hypokalemia, and hypomagnesemia) associated with this syndrome.[7] The patient had no neurologic signs or symptoms, but the unforeseen side effects of camphor on a developing brain cannot be estimated.

The use of cold remedies in small children is of questionable benefit, and such agents may be potentially dangerous. Even if the package inserts of camphor-containing cold remedies do not recommend their use in children less than 2 years of age, these remedies are widely available to a general public unaware of their toxicity. Health professionals should be aware of camphor toxicity in young children and warn the parents about their potential dangers.


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