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Acetaminophen and children: Why dosage matters

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Acetaminophen and children: Why dosage matters

An acetaminophen overdose is serious — and it can happen easier than you might think. Here's how to protect your child, and when to seek emergency care.

By Mayo Clinic staff

Acetaminophen (Tylenol, others) has long been a standard remedy for fever and pain in children. It's effective and readily available without a prescription. In excess, however, even good things can be harmful. Here's what you need to know about acetaminophen overdoses and children.

How does an acetaminophen overdose occur?

An acetaminophen overdose is serious, and it can occur all too easily. Consider these scenarios:

  • You're in a hurry. You might unwittingly give your child too much acetaminophen if you don't take the time to carefully measure the medication — or if you don't realize that another caregiver has already given your child a dose of medication.
  • You combine medications. If your child has various cold symptoms, you might combine acetaminophen with a cold remedy. But this can be dangerous because many cold medications already contain acetaminophen.
  • You use the wrong formulation. You might cause an overdose if you give your child adult acetaminophen tablets instead of the children's formulation. Even the children's versions of acetaminophen come in many different formulations, and the dosage varies for each one. For example, infant drops are more concentrated than is the liquid acetaminophen typically given to toddlers. If you assume that both liquids contain the same amount of medicine, substituting infant drops for syrup could lead to an acetaminophen overdose.
  • You decide that more is better. If you're not satisfied with the performance of the recommended dosage of acetaminophen, you might increase the dosage and cause an accidental overdose.
  • Your child mistakes the medication for candy or juice. Overdoses often occur when a child mistakes acetaminophen for something safe to eat or drink. Sometimes this happens when an adult leaves the bottle open or accessible after taking his or her own medication.

How much acetaminophen is too much?

If you give your child acetaminophen, read the product label carefully to determine the correct dosage based on your child's age and weight. Too much acetaminophen overloads the liver's ability to process the drug safely. An acetaminophen overdose can lead to life-threatening liver problems.

How much acetaminophen is too much varies depending on the child's age and weight. Consider these guidelines from the American Association of Poison Control Centers:

  • Age 5 and younger. Seek emergency care if your child age 5 or younger swallows 91 milligrams (mg) of acetaminophen per pound of his or her weight (200 mg per kilogram, or kg) in 24 hours.
  • Age 6 and older. Seek emergency care if your child age 6 or older swallows 91 mg of acetaminophen per pound of his or her weight (200 mg per kg) or at least 10,000 mg of acetaminophen — whichever is less.

Guide to toxic doses of acetaminophen, based on a child's weight and type of acetaminophen

Child's weight Toxic amount over 24 hours Toxic amount based on dosage form
Infant drops* Children's liquid** 160-mg chewable tablets Adult-strength 500-mg tablets
20 pounds (9 kg) 1,818 mg or more 3.6 teaspoons, or tsp. (18.2 milliliters, or mL) 11.4 tsp. (56.8 mL) 11.4 3.6
30 pounds (14 kg) 2,727 mg or more 5.5 tsp. (27.3 mL) 17 tsp. (85.2 mL) 17 5.5
40 pounds (18 kg) 3,636 mg or more 7.3 tsp. (36.4 mL) 22.7 tsp. (113.6 mL) 22.7 7.3
50 pounds (23 kg) 4,545 mg or more 9.1 tsp. (45.5 mL) 28.4 tsp. (142 mL) 28.4 9.1
60 pounds (27 kg) 5,454 mg or more 10.9 tsp. (54.5 mL) 34.1 tsp. (170.5 mL) 34.1 10.9
70 pounds (32 kg) 6,363 mg or more 12.7 tsp. (63.9 mL) 39.8 tsp. (198.9 mL) 39.8 12.7
80 pounds (36 kg) 7,273 mg or more 14.5 tsp. (72.7 mL) 45.5 tsp. (227.3 mL) 45.5 14.5

*80 mg per 0.8 mL, which equals one dropperful
**160 mg per 5 mL, which equals 1 tsp.

Note: This table is a general guide only, not a substitute for a consultation with a trained poison specialist. If you're concerned about an acetaminophen overdose, contact your local poison control center at 800-222-1222 or seek emergency care.

How is an acetaminophen overdose treated?

If your child ingests more than the recommended amount of acetaminophen but not enough to cause a toxic reaction, medical care isn't likely necessary. Be cautious, however. If you're concerned about a possible acetaminophen overdose or notice early signs or symptoms of an overdose — nausea, vomiting, lethargy and abdominal pain within 24 hours — call your local poison control center at 800-222-1222 or seek emergency care.

In the hospital, a child with an acetaminophen overdose may be given activated charcoal to decrease absorption of the acetaminophen. Activated charcoal is usually given as a black liquid drink, but it can be given through a tube inserted through the mouth or nose and into the stomach if necessary. If the overdose is severe, the child may need an antidote to reverse the effects of the acetaminophen. The antidote should be given within eight to 10 hours after the acetaminophen is swallowed.

Left untreated, a serious acetaminophen overdose may be fatal within a few days. Careful use of acetaminophen and prompt treatment in case of an overdose can help prevent a tragedy.

References
  1. Dyer KS. Acetaminophen (paracetamol) poisoning in children and adolescents. http://www.uptodate.com/home/index.html. Accessed March 2, 2009.
  2. James LP, et al. Acetaminophen-associated hepatic injury: Evaluation of acetaminophen protein adducts in children and adolescents with acetaminophen overdose. Clinical Pharmacology and Therapeutics. 2008;84:684.
  3. Kanter MZ. Comparison of oral and i.v. acetylcysteine in the treatment of acetaminophen poisoning. American Journal of Health-System Pharmacy. 2006;63:1821.
  4. Brok J, et al. Interventions for paracetamol (acetaminophen) overdose. Cochrane Database of Systematic Reviews. 2006:CD003328.
  5. Mahadevan SK, et al. Paracetamol induced hepatotoxicity. Archives of Disease in Childhood. 2006;91:598.
  6. Acetaminophen - Hennepin Regional Poison Center treatment guidelines. Minneapolis, Minn.: Hennepin County Medical Center. Accessed April 16, 2009.
  7. Smith DH. Managing acute acetaminophen toxicity. Nursing. 2007;37:58.
  8. Dart RC, et al. Acetaminophen poisoning: An evidence-based consensus guideline for out-of-hospital management. Clinical Toxicology. 2006;44:1.
  9. Dart RC (expert opinion). Rocky Mountain Poison and Drug Center, Denver, Colo. May 6, 2009.
  10. Hoecker JL (expert opinion). Mayo Clinic, Rochester, Minn. May 7, 2009.

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June 19, 2009

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