"How Will I Ever Remember the Dose for Tylenol®?"

Patient Presentation
An 18-month-old female came to clinic with upper respiratory tract symptoms and a fever to 101° F for two days. She was drinking well and playing but since she had a history of several ear infections her parents wanted her examined. She was otherwise well. The pertinent physical exam showed an alert female in no distress with normal vital signs and a temperature to 99.8° F temperature. She had rhinorrhea but her ears and the rest of her examination were normal. The diagnosis of an upper respiratory tract infection was made. As the new intern physician was counseling the family, the father asked what the proper dose of Tylenol® was. The intern consulted her pocket handbook and gave the parents the proper dosage for the acetaminophen. After the patient encounter, the intern was discussing how this dosing question was such a common parent question and that she felt she would never be able to remember the proper dosing especially with all the different forms of the medication available. Her attending physician said, “You need to learn the Rules of 10s – 80s and 100s and then you will always remember.” He then sat down and explained the general rule to her and the other interns and medical students in the room.

Parents always have a number of common questions that any pediatric healthcare provider should be able to answer easily because they are so common. The proper dosing of antipyretics/analgesics is one of those questions. Parents often have this particular question because the labeling directions may tell the parent to contact a physician or they are concerned that they may be giving too much of the medication. Parents are often surprised to know that they are actually underdosing the medication because the child often has gained weight and therefore needs more medication for it to be effective.

In an emergency room study, parents were asked to state the antipyretic dosage they would use for their child and then were asked to draw up the correct dosage using real medication and syringes/teaspoons etc. Overall, 40% of parents could accurately state the correct dosage, and only 30% could accurately state and then demonstrate drawing up the correct antipyretic dosage for their child. In another emergency room study, only 49% of children who received a known amount of antipyretic medication received a correct dosage. Infants less than 1 year of age were much more likely to receive an inaccurate dosage. This study also found that medication dosage based upon parental weight estimation was more likely to have an accurate dosage.

Pediatric health care providers often cannot show a parent how to draw up the correct dosage in the office or emergency room setting. However, they can be familiar with common forms of the medication and common ways they are dispensed. Questioning the parents about what form of medication they have, and how they give it gives the health care provider the chance determine an accurate dosage and then verbally tell and write down how much the parent should give using what is available in the home. This also models for the parent using weight to obtain an accurate dose.

Learning Point
One method to remember common forms of antipyretic medication is the Rule of 10s, 80s and 100s.
Abbreviations used below are: mg = milligrams, ml = milliliters, and kg = kilogram

Dosing – The Rule of 10s

Multiply the weight of the child in kilograms x 10 to give an estimated dose in milligrams (kg x 10 = dose in mg). Then adjust the dose up or down to a convenient amount of the medication for the parent to give the child based upon what form of medication and method to deliver it is available such as a syringe, cup, medication spoon, etc.

		Acetaminophen		Ibuprofen
Dosing 		10-15 mg/kg/dose	5-10 mg/kg/dose
Dosing interval	every 4-6 hours		every 6-8 hours

For example, a child weighs 15 kilograms and the parent has infant drop acetaminophen at home.
15 kg x 10 = 150 mg/dose
Because the dosing range for acetaminophen is 10-15 mg/kg/dose. The 150 mg/dose can be rounded up to 160 mg/dose which is 1.6 ml or 2 droppers of acetaminophen.
If on the other hand the parent had chewable ibuprofen tablets available at home, the dose would be 150 mg which is 1.5 tablets/dose.

Whole amounts are easier to accurately give than 1/2 amounts. Quarter and 3/4 amounts are often difficult to give. For example, give a whole or 1/2 tablet if possible as giving 1/4 or 3/4 of a tablet is more difficult.

Acetaminophen – the Rule of 80s

Acetaminophen concentrations are usually in some variant of 80 milligrams, the exceptions are dosages of 325 mg (close to 4 x 80 mg), 500 mg and 650 mg (close to 8 x 80 mg) in the tablet forms. Maximum dose is 4 grams/24 hours or 5 doses/24 hours.

Drug form	Common Parent Names	Concentration

Suspension/syrup/elixir "syringe-kind" 	160 mg/5 mls
Chewable tablets"chewables" 		80 or 160 mg/tablet
Tablets/capsules			160, 325, 500, or 650 mg/tablet
/caplets/geltabs "tablet"
Suppositories	"rectal"	 	80, 160, 325, or 650 mg/suppository

*Note bene: In the fall of 2011 all liquid brands of acetaminophen changed to a single concentration of 160 mg/5 ml. Previously there were two different concentrations.

Ibuprofen – the Rule of 100s

Ibuprofen concentrations are usually in some variant of 100 milligrams. Droppers for the administration of ibuprofen are usually marked .625 mls (= 25 mg), 1.25 mls (= 50 mg) and 1.875 ml (= 150 mg) to assist in dosing. Common parent names are the same and so are omitted here. Maximum dose is 40 mg/kg/24 hours.

Drug form		Concentration
Infant drops		50 mg/1.25 mls
Suspension/syrup/ 	100 mg/5 mls
Chewable tablets 	50 or 100 mg/tablet
Tablets/capsules	100, 200, 400, 600, or 800 mg/tablet

Questions for Further Discussion
1. What other names do parents have for the different forms of acetaminophen and ibuprofen?
2. What are other common medication questions that parents have?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Information prescriptions for patients can be found at MedlinePlus for these topics: Pain Relievers and Over-the-Counter Medicines
and at Pediatric Common Questions, Quick Answers for this topic: Pain Management

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Simon HK, Weinkle DA. Over-the-counter medications. Do parents give what they intend to give? Arch Pediatr Adolesc Med. 1997 Jul;151(7):654-6.

Li SF, Lacher B, Crain EF.
Acetaminophen and ibuprofen dosing by parents. Pediatr Emerg Care. 2000 Dec;16(6):394-7.

Robertson J, Shilkofski N. The Harriet Lane Handbook. 17th. Edit. Mosby Publications: St. Louis. 2005:688-689,839-840.

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
    16. Learning of students and other health care professionals is facilitated.

    Donna M. D’Alessandro, MD
    Professor of Pediatrics, Children’s Hospital of Iowa