Definition/Introduction

Young's Rule is an equation used to calculate pediatric medication dosage based on the patient's age and the known recommended adult dose. The definition of Young's Rule is the age of the patient, divided by the age added to twelve, all multiplied by the recommended adult dose. This formula appears below:

[Age / (Age + 12)] x Recommended Adult Dose = Pediatric Dose

Young's Rule can be applied to quickly approach a situation in which the patient's weight is unknown. Other approaches to pediatric dosing that also use age include Webster's Rule and Fried's Rule. 

If the weight of the patient is known, Clark's Rule or the Body Surface Area rule can be implemented.[1]

Issues of Concern

Pediatric dosing based on one's age has the potential for suboptimal therapeutic levels due to the broad range of potential weight, especially with increasing childhood obesity.[2][3]

Clinical Significance

In situations where the pediatric patient's weight is unknown, for instance, at the point of injury, then Young's Rule can be safely implemented if their age and the recommended adult dosing are known. Additionally, certain classes of medications require weight-based dosing, such as antibiotics and antiepileptics. Ultimately, age-based dosing has been demonstrated to be a safe and effective approach. However, caution should be used depending on the class of the drug.[4][5]

Nursing, Allied Health, and Interprofessional Team Interventions

Knowledge of Young's RUle can serve several purposes in pediatric drug dosing, and members of the interprofessional healthcare team would do well to be familiar with the rule. The most obvious use is for the clinician when calculating the dose for a pediatric patient. A secondary use can be to verify that the dose ordered or prescribed is not outside of the parameters for the child. This is where nurses, during administration or pharmacists, when filling an order or prescription, can apply the rule and potentially stop a toxic dose or a therapeutically insufficient dose. In an open, interprofessional team environment, this can improve patient outcomes and prevent adverse events. [Level 5]