Guaifenesin Pediatric Dosing
Guaifenesin is not recommended for children under 12 years of age according to FDA labeling, which only approves dosing for adolescents 12 years and older at 600-1200 mg every 12 hours (extended-release formulation). 1
FDA-Approved Dosing (Extended-Release Formulation)
- Children under 12 years: Do not use 1
- Adolescents ≥12 years: 600 mg (1 tablet) every 12 hours, maximum 1200 mg in 24 hours 1
- Administration: Take with a full glass of water; do not crush, chew, or break tablet; can be given without regard to meals 1
Off-Label Dosing Considerations
While the FDA label restricts use to children ≥12 years, pharmacokinetic studies have evaluated guaifenesin in younger children:
Age-Based Dosing from Research Studies
- Children 2-11 years: 100-200 mg per dose has been studied, with dosing typically every 4 hours for immediate-release formulations 2
- Adolescents 12-17 years: 200-400 mg per dose every 4 hours for immediate-release formulations 2
The pharmacokinetic data demonstrate that oral clearance and volume of distribution increase with age due to body size, but no maturation-related changes in drug handling occur beyond allometric scaling 2. When comparing upper doses for children (2-11 years) with lower doses for adolescents (12-17 years), similar systemic exposure was observed 2.
Practical Dosing Guidance
For immediate-release formulations (if used off-label):
- Dosing range: 200-400 mg every 4 hours, up to 6 times daily 3
- The American Academy of Pediatrics notes that guaifenesin doses can be rounded by up to 15% for ease of home administration 4
- When using combination products, ensure the guaifenesin component does not exceed maximum daily limits 4
Important Clinical Caveats
- Limited pediatric evidence: The efficacy of guaifenesin as an antitussive has not been convincingly demonstrated in controlled trials, even in adults 5
- Formulation matters: Extended-release formulations provide 12-hour dosing convenience but are only FDA-approved for ages ≥12 years 1, 6
- Multiple daily doses required: Immediate-release formulations require dosing every 4 hours to maintain therapeutic effect due to guaifenesin's short half-life 3, 6
- Food effects: For extended-release formulations, food delays time to maximum concentration but does not affect overall exposure 6
The safest approach is to follow FDA labeling and avoid guaifenesin in children under 12 years unless specifically directed by a physician for off-label use, recognizing the limited evidence for efficacy in pediatric populations.