Is Guaifenesin a Controlled Substance?
No, guaifenesin is not a controlled substance—it is an over-the-counter (OTC) expectorant available without prescription in the United States and Canada. 1
Regulatory Status
Guaifenesin remains the only legally marketed expectorant in the United States per OTC Monograph, meaning it is approved for sale without prescription and without controlled substance restrictions. 1
The medication is available in numerous OTC cough/cold formulations, both as a single-ingredient product and in combination with antihistamines, cough suppressants, and decongestants. 2
No special prescribing, dispensing, or tracking requirements exist for guaifenesin, unlike controlled substances (Schedule II-V medications) which require DEA registration, special prescription forms, and inventory controls. 1
Clinical Context
Guaifenesin works as a mucoactive drug by loosening mucus in airways and making coughs more productive, with a mechanism fundamentally different from controlled substances like opioid antitussives (codeine) or stimulants. 1
The drug has a well-established and favorable safety profile in both adult and pediatric populations, with generally mild documented side effects under normal use. 1, 2
Standard dosing is 200-400 mg every 4 hours (up to 6 times daily) for immediate-release formulations, or 600-1200 mg every 12 hours for extended-release products, all available without prescription. 1, 3
Important Safety Note
While not a controlled substance, one case report documented a fatal overdose with guaifenesin at 25.0 μg/mL in femoral blood following intentional ingestion, demonstrating that even OTC medications can be lethal in massive overdose. 2 However, this does not change its non-controlled regulatory status.