Maximum Dose of Guaifenesin
The maximum recommended dose of guaifenesin is 2,400 mg per day, administered as 400 mg every 4 hours (up to 6 times daily) for immediate-release formulations, or 1,200 mg every 12 hours for extended-release formulations. 1
Dosing Regimens
Immediate-Release Formulations
- Standard dosing: 200-400 mg every 4 hours 1
- Maximum daily dose: 2,400 mg (400 mg × 6 doses) 1
- Multiple daily doses are required to maintain 24-hour therapeutic effect due to guaifenesin's short half-life 1
Extended-Release Formulations
- Standard dosing: 600-1,200 mg every 12 hours 2
- Maximum single dose: 1,200 mg 2
- Maximum daily dose: 2,400 mg (1,200 mg × 2 doses) 2, 3
- Extended-release formulations provide convenience with 12-hourly dosing compared to immediate-release products 1
Clinical Context
The dosing range allows flexible dose titration to increase plasma concentrations as needed for symptom control 1. Extended-release guaifenesin has been demonstrated to be bioequivalent to corresponding over-the-counter monograph doses of immediate-release guaifenesin at steady state 2.
Safety Considerations
- Guaifenesin has a well-established and favorable safety profile in adult and pediatric populations 1
- In a post-marketing surveillance study of 552 adults taking extended-release guaifenesin 1,200 mg every 12 hours for 7 days, all adverse events were mild in severity with no serious adverse events or deaths 3
- Critical warning: One case report documented a fatal overdose with guaifenesin at 25.0 μg/mL in femoral blood, resulting in central nervous system depression and asystole approximately 2 hours after ingestion 4