Pediatric Medication Dosing: Parent's Complete Safety Guide

Why Pediatric Dosing Is Different

The phrase "children are not small adults" is foundational in pediatric pharmacology. Medicine metabolism, distribution, and elimination differ dramatically across developmental stages — and dosing errors are among the most dangerous medication errors in pediatrics.

Key physiological differences:

• Body composition: Higher total body water in neonates (80% vs 60% in adults); lower fat stores; lower protein binding
• Liver enzymes: CYP enzyme expression develops gradually; CYP3A4 peaks at age 1-5, then decreases to adult levels; neonates cannot metabolize many medicines efficiently
• Kidney function: Neonatal GFR is 2-4 mL/min/1.73m² (vs 120 in adults); reaches adult levels by age 1-2
• Blood-brain barrier: Less complete in young infants; medicines enter CNS more readily (opioid sensitivity)
• Absorption: Gastric pH higher in infants (affects acid-labile medicine stability); slower gastric emptying

---

Weight-Based Dosing: The Foundation

Most pediatric medicines are dosed by mg/kg up to a maximum adult dose. Weight-based dosing accounts for children's smaller body mass and higher metabolic rate.

Critical rule: Always use current weight, not age, as primary dosing parameter.

Example: Amoxicillin for otitis media

• Dose: 40-90 mg/kg/day divided every 8-12 hours
• Child weighs 20 kg
• Dose range: 800-1800 mg/day
• If given TID: 267-600 mg per dose
• Maximum: Adult dose (usually 500-875 mg TID) — do not exceed

Practical tip: Keep your child's weight in pounds AND kilograms. 1 kg = 2.2 lbs. A 44-lb child = 20 kg.

---

OTC Medications: Common Parent Questions

Acetaminophen (Tylenol)

• Dose: 10-15 mg/kg every 4-6 hours (max 5 doses/24 hours)
• Max daily dose: 75 mg/kg/day or 4000 mg/day (whichever is less)
• Product concentration: Infant drops (160 mg/5 mL) and children's liquid (160 mg/5 mL) are now the SAME concentration — reduces dosing confusion
• Not for: Neonates under 2 months without medical guidance
• Danger: Acetaminophen is the leading cause of acute liver failure in the US — overwhelmingly from unintentional overdose (multiple combination products taken simultaneously)

Ibuprofen (Advil, Motrin)

• Dose: 5-10 mg/kg every 6-8 hours
• Not for: < 6 months of age; dehydration (renal risk); bleeding or platelet disorders
• Reye's syndrome note: Ibuprofen does NOT cause Reye's syndrome (aspirin does) — it is safe for viral illnesses

Aspirin

• Avoid in children under 18 with viral illness — risk of Reye's syndrome (rare but potentially fatal liver/brain toxicity)
• Exception: Kawasaki disease treatment under physician direction

Cough and Cold Medications

• FDA guidance: OTC cough/cold products should NOT be used in children under 4 years (some say under 6)
• No efficacy evidence in young children
• Risk of serious adverse events: convulsions, rapid heart rate, death (particularly antihistamines and decongestants)

Antihistamines

• Diphenhydramine (Benadryl): Not recommended under 2; sedating; cognitive impairment
• Cetirizine (Zyrtec), loratadine (Claritin): 2nd generation; safer; approved age 2+

---

Prescription Pediatric Medications: Key Points

Antibiotics

• Never use leftover antibiotics — incomplete courses promote resistance; dosing may be wrong for current illness
• Amoxicillin: First-line for otitis media, strep pharyngitis, most community pneumonia
• Azithromycin (Z-pack): Convenient but overused; resistance concerns; cardiac risk in patients with prolonged QT
• Fluoroquinolones: Generally avoided in children under 18 — concerns about cartilage toxicity (though increasingly used when benefit outweighs risk)
• Tetracyclines: Avoid under 8 — permanent tooth discoloration

Compounding

When commercial formulations are unavailable, compounding pharmacies prepare custom concentrations. Verify compounded preparations from a state-licensed pharmacy for quality assurance.

---

Medication Administration Tips

Oral liquids:

• Use the measuring device that comes with the medication (oral syringe, dosing cup)
• Never use kitchen spoons — teaspoon varies by 2-7 mL
• Place oral syringe inside cheek (buccal mucosa) — not back of throat

Tablets:

• Children 6+ can often swallow small tablets with practice
• Check if tablets can be crushed or capsules opened (not all can)
• Mix in small amount of food if needed — verify with pharmacist for specific medicine

Eye/ear drops:

• Warm to body temperature (hold in hands 2 minutes) — reduces discomfort
• Eye drops: pull down lower lid; don't touch dropper to eye