One Pill Can Kill: The Case of the Shaking Schoolgirl

Welcome to the fifth case in the One Pill Can Kill series. In this article we’ll review over-the-counter products that contain camphor, often used in creams and lotions that can be toxic to children. You may never have heard of camphor, but you’ve certainly seen it in drugstore aisles and may even have camphor-containing products in your medicine cabinet. Camphor poisoning isn’t a hypothetical idea dreamed up by evil examiners. Here’s a case based on data collected by my local poison control center.

Sunday, 13:42

Emergency call: A 5-year-old girl in seizure at home. She was febrile earlier.

You and your partner share a disconcerted look as you leave the base. Lights and siren on, you worry you’ll find a flat child with the purpuric rash typical of meningitis. You mask up, gown up, and enter the suburban house expecting the worst.

The front door is unlocked, and a worried voice calls you upstairs. You arrive in a child’s room to find a concerned pair of parents holding their daughter, who is awake but disoriented. The mother tells you she’s been unwell with a runny nose and nonproductive cough for 24 hours. She had a fever of 38.9ºC (102.2ºF) today, and they’ve not given her oral medications because “we want her immune system to work naturally.”

On physical exam the child is confused and quiet. She can name her parents and says she is in her bedroom. Her heart rate is 100, and her peripheral and central capillary refill is two seconds. Her extremities are warm. Her blood pressure is normal, as is her respiratory rate. Her glucose is normal. Her temperature now is 37.6ºC (99.7ºF). Auscultation is clear, and you notice she has sniffles. Her oropharynx is normal, with no tongue bite marks or erythema. She has no lymphadenopathy. Her abdomen is normal. There are no skin findings, and her neck is supple. You ask her to stand up and take a few steps, but she is very wobbly, and you help her lie back down.

On history the child has no medical problems and is not immunized. She is developmentally normal. Her parents rubbed a naturopathic gel on her chest when she awoke at 0800, and that seemed to help with the cough. Since then the mother and father have been applying the gel to the child’s chest and back every hour. “It’s like Vicks VapoRub, but natural,” they tell you. The bottle lists no ingredients but has a picture of evergreen trees on the front. It smells strong, but you can’t quite recognize it—not menthol, not wintergreen, but something that really gets into your nostrils.

Prep time:

• List 10 toxic differential diagnoses for children in seizure.
• List three first-line medications to terminate seizures in children.
• Which first-line seizure medications can be given via the IM and IN routes?
• Which first-line seizure medications can be given via the PR route?
• What are your next three steps once arriving at the patient’s side?

You suspect a febrile seizure, but you’re uncomfortable with her age. She’s a bit old, though not out of the window entirely, and her previous fever worries you for bacteremia or meningitis. You load her into the ambulance and transport, and 10 minutes out she has a sudden full-body seizure. You draw up a benzodiazepine and attempt IV access, but her seizure stops before you can secure the line. It lasted about two minutes. As your partner stops in the ambulance bay, you get flash and secure a saline lock just as the rear doors open.

While in line to be triaged, she begins to seize again. You pull the benzodiazepine and administer an IV dose. The seizure stops about 30 seconds later. The triage nurse directs you to a bed. You hand over to the nurse as the child begins to rouse from her postictal state. Her glucose remains normal.

Camphor-Containing Products

Camphor is a natural product from some members of the laurel family of evergreen trees. While it is FDA approved when sold as less than 11% of the content of the product and commonly found in households, little evidence supports its therapeutic promises of relieving headaches, coughs, and joint pain. Still, my mother always rubbed Vicks VapoRub on my chest when I had a childhood cold, and it remains in her medicine cabinet today. Further, many stores sell products containing illegally high amounts of camphor, and it may not be included on product labels.

There are several over-the-counter products containing camphor. Examples include Vicks VapoRub, Tiger Balm, and other medicinal creams and oils. It’s also sold as a solid, in blocks that resemble sugar cubes that are burned in eastern religious ceremonies or as tablets. You probably best know camphor for its role in mothballs.

While you might not think kids would eat these products, many have scents that may be appealing, leading to oral consumption. Children under 3 learn about their environments by pica, which is putting objects into their mouth. As little as 3–5 mL of 20% camphor can be toxic—that’s less than one teaspoon. Once ingested, even a small amount can rapidly cause toxicity. Further, overzealous parents may apply a toxic amount of these creams to their children, leading to toxicity.

Camphor is quickly absorbed through skin and mucous membranes, and there are case reports of inhalational toxicity in children.

Camphor is a parasympatholytic agent, which is an antagonist at the nicotinic acetylcholine receptor. These receptors are nonmuscarinic—you won’t see the SLUDGE symptoms of the cholinergic crisis seen with pesticides and nerve agents (salivation, lacrimation, urination, defecation, GI symptoms, emesis), and your patient won’t die from the killer Bs (bronchorrhea, bronchospasm, bradycardia).

Instead, the nicotinic receptors transmit signals from the presynaptic to postsynaptic cells within the sympathetic and parasympathetic nervous systems, leading to neuronal excitation and seizures. You may notice hallucinations, delirium, lethargy, ataxia, poor coordination, or seizures. Gastrointestinal symptoms such as nausea, vomiting, and diarrhea are also common. Long QT intervals have been reported.

Activated charcoal and ipecac syrup are not recommended. Seizures usually abort with standard benzodiazepine doses. Respiratory support is sometimes needed but not always.

Fortunately, camphor’s rapid action means most exposures will become clinically apparent within 90 minutes; observation of four hours is considered adequate to discharge the child from medical care if neurological symptoms do not occur. Children with symptoms are observed in the hospital for 24 hours.

Here’s a list of toxic causes of pediatric seizures represented by an easy-to-remember mnemonic:

OTIS CAMPBELL

• Organophosphates;
• Tricyclic antidepressants;
• Isoniazid;
• Sympathomimetics;
• Camphor;
• Amphetamines;
• Methylxanthines;
• Propranolol;
• Botanicals (like the gyrometria mushroom discussed in the previous case);
• Ethanol and benzodiazepine withdrawal;
• Lithium;
• Lidocaine.

After a decade working as a helicopter paramedic, Blair Bigham, MD, MSc, EMT-P, completed medical school. He is now an attending emergency physician in Ontario and critical care fellow in California. E-mail him at blair.bigham@medportal.ca; on Twitter follow @BlairBigham.