Too many children are overdosing on the common over-the-counter painkiller acetaminophen, report Canadian doctors, who say more must be done to prevent the errors.

"Acetaminophen overdose is a major cause of acute liver failure and is the most common identifiable cause of acute liver failure in children," write Dr. Rod Lim from the Children's Hospital at London Health Sciences Centres and his co-authors in the Canadian Medical Association Journal.

Lim says acetaminophen -- which is often sold as Tylenol as well as generically -- can lead to liver failure and death in a number of ways, including a one-time overdose or through repeated too-high doses.

They say accidental overdoses are often the result of parents who fail to understand proper dosage instructions.

The authors cite the case of a 22-day-old baby who had just had a circumcision. The parents misunderstood the correct dose, and when the doctor instructed the parents on how to give another dose, they realized the error they had already made.

The child survived because doctors were able to give him N-acetylcysteine, the standard intravenous treatment for liver toxicity related to acetaminophen overdoses.

The treatment is usually successful if started within eight hours after ingesting the drug. In this case, the child recovered within about 24 hours after the overdose.

A report from the U.S. poison control centre and the American Academy of Pediatrics, which analyzed 238 instances of serious medication errors in children under age six, found that acetaminophen overdose was the most common single agent responsible for a life-threatening event or death.

The CMAJ article notes that medication dosing in children can be complicated because of the need to adjust it based on the child's weight.

They have a number of suggestions for preventing these avoidable and life-threatening errors, including:

  • better labelling and dosing information
  • improved dosing devices
  • placing acetaminophen behind the counter to ensure that a pharmacist can counsel parents on correct dosing.

The authors write that while physicians and pharmacists should continue to educate caregivers about proper dosage, "…error reduction on a large scale requires systems-based interventions and prevention."