guaifenesin
Brand: Mucinex, Robitussin, Organidin NR
Prototype Drug
Drug Class: expectorant
Drug Family: mucolytic/expectorant
Subclass: mucokinetic agent
Organ Systems: respiratory
Mechanism of Action
Reduces surface tension of respiratory tract secretions and stimulates the ciliary and secretory cells of the respiratory tract by reflex action; increases the volume and decreases the viscosity of respiratory secretions, facilitating mucociliary clearance; the precise molecular mechanism remains incompletely characterized.
airway mucus viscosity (indirect)
Indications
- productive cough (expectorant)
- loosening and thinning respiratory secretions
- chest congestion associated with upper respiratory infections, bronchitis, influenza
Contraindications
- hypersensitivity to guaifenesin
Adverse Effects
Common
- nausea
- vomiting
- dizziness
- headache
- rash
Serious
- kidney stones (rare — uricosuric effect may rarely be relevant)
- hypersensitivity (rare)
Pharmacokinetics (ADME)
| Absorption | oral; well absorbed; rapidly distributed |
| Distribution | widely distributed |
| Metabolism | hepatic hydrolysis and oxidation |
| Excretion | renal |
| Half-life | approximately 1 hour |
| Onset | 30 minutes |
| Peak | 30-60 minutes |
| Duration | 4-6 hours (immediate-release); 12 hours (extended-release) |
| Protein Binding | unknown |
| Vd | not well characterized |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| no significant pharmacokinetic interactions known | no known CYP involvement; minimal protein binding; low interaction potential | minor |
Nursing Considerations
- Encourage adequate fluid intake (8 or more glasses of water daily) with guaifenesin therapy to maximize its mucokinetic effect — hydration is as important as the drug itself for thinning secretions.
- Extended-release tablets (Mucinex) should not be crushed or chewed; immediate-release liquid or tablets may be more suitable for patients with dysphagia or pediatric patients.
- Advise patients that guaifenesin can cause nausea, particularly at higher doses; taking with food may reduce nausea.
- Counsel patients that guaifenesin treats cough productively by loosening secretions but does not suppress cough; it should not be combined with antitussives if the goal is productive expectoration.
Clinical Pearls
- Guaifenesin is the only FDA-approved expectorant in the United States, though its clinical efficacy over placebo in controlled trials has been modest; strong clinical evidence for meaningful benefit in most respiratory conditions remains limited.
- High-dose guaifenesin (2400 mg/day) has been used investigationally for fibromyalgia (the 'guaifenesin protocol') — this use is not supported by controlled clinical evidence and should not be recommended by healthcare professionals.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.