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Calculating Pediatric Medication Dosages on the NCLEX-RN

Calculating Pediatric Medication Dosages NCLEX-RN
Pediatric medication dosages are based on a child’s weight. There is no standard based on age since a child’s size can vary greatly. As a result, you will need to calculate out the correct dosage for the child based on his or her weight.

Don’t get nervous about this — the calculations are very straight forward. With a little bit of practice, you can greatly increase your confidence and ability to correctly and safely calculate medication dosages for children. As a pediatric nurse, I do this constantly and it just becomes a routine part of checking your patient’s medications.

It is also important to remember that when you are teaching new parents, you must remind them that they should always call their child’s doctor if they have any questions about how much of an over the counter medication they should administer. As a nurse, you always need to verify what strength the medication in the home is by having the parent read the exact mg/ml on the label. Taking your time and double checking your calculations will aid in you successfully answering these type of questions on your NCLEX-RN exam and ensuring that in real practice your patient’s receive safe care.

Conversion of Body Weight

To convert pound to kilograms, divide by 2.2 since 1 kg = 2.2lbs.

To convert kilograms to pounds, multiply by 2.2 since 1 kg = 2.2lbs.

Practice Concerting the following:

a. 10 lbs = __________kg

b. 25 lbs = __________kg

c. 32 lbs = __________kg

d. 110kg = __________lbs

e. 68 kg = __________lbs

(Answers: a. 4.5 b. 11.4 c. 14.5 d. 242 e. 149.6 )

Dosage Calculations

To calculate the number of tablets per dose that a child should take use the following formula:

Desired x Tablet = ________ tablets per dose


To calculate the volume of medication to be administered per dose to a child use the following formula:

Desired x Volume = __________ml per dose


Practice Calculating doses:


a) A 25lb child was ordered for Tylenol 115mg PO every 4 hour hours as needed for pain. Is this a safe dose (standard is 10-15/kg/dose)? How many mls would you administer (Tylenol 160mg/5ml)?

b) A 55 lb child was ordered for ibuprofen 300mg every 6 hours as needed for pain. Is this a safe dose (standard is 5-10mg/kg/dose)? What is the maximum dose that this child should receive per dose in mg and mls?

c) A 55lb child requires a dose of Benadryl and he will only take the chewable tablets. The doctor orders 25mg every 6 hours as needed for hives. How many tablets will the child receive per dose? (Benadryl chewable tablet – 12.5mg)

d) The nurse practitioner orders ampicillin sodium 150mg IV every 6 hours. The medication label reads 1g and reconstitute with 7.4ml of bacteriostatic water. How many mls will you need to draw up for a dose?

Answers (a. Yes a safe dose – 3.6ml b. No – Maximum dose would be 250mg c. 2 tablets d. 1.1ml)

Remember, practice will help you succeed. Take your time and complete as many practice questions as possible. Preparing well for your NCLEX-RN exam will help you pass and prepare you to enter the nursing field with confidence.

About Michelle

Michelle Besmer is dedicated to preparing the next generation of nurses for successful careers. She completed her Bachelors of Nursing and her Masters as a Certified Pediatric Nurse Practitioner at Rutgers University. She has practiced and trained nurses in pediatrics for over 15 years. In her free time, she enjoys spending time with her family, baking and playing trumpet.

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