Guaifenesin
Guaifenesin
Brand names:Mucinex, Robitussin, Humibid
The only FDA-approved oral expectorant in the United States, used to thin and loosen respiratory mucus and facilitate productive cough. Guaifenesin is widely available over the counter and is operationally useful in deployment medicine for upper respiratory infections with thick mucus and difficulty clearing secretions.
Pharmacology and Actions
Guaifenesin's mechanism is incompletely understood. The drug appears to increase respiratory tract fluid by stimulating vagal nerve receptors in gastric mucosa, which reflexively increases respiratory secretions. The result is thinning of mucus, reduced viscosity, and easier expectoration. Adequate hydration is essential for guaifenesin to work effectively; the drug cannot thin mucus that is dry from systemic dehydration.
Indications
- Productive cough with thick or tenacious mucus
- Acute bronchitis and upper respiratory infection symptom relief
- Adjunct to antibiotic therapy for productive infections
- Chronic obstructive pulmonary disease exacerbations (symptom relief)
Absolute Contraindications
- Known guaifenesin allergy
- Persistent or chronic cough with smoking, asthma, chronic bronchitis, or emphysema without medical evaluation
- Cough accompanied by excessive secretions in patients unable to clear them effectively
Precautions and Side Effects
Generally well tolerated. GI upset, nausea, vomiting, and headache can occur. Drowsiness is uncommon. Kidney stones have been associated with high doses in chronic use. The drug requires adequate hydration to work; advise patients to drink fluids. Some combination products with codeine or pseudoephedrine carry additional precautions related to those ingredients.
Adult Dosing
Pediatric Dosing
Pediatric dosing: 2 to 6 years, 50 to 100 mg PO every 4 hours. 6 to 12 years, 100 to 200 mg PO every 4 hours. 12 years and older, adult dosing. Avoid in children under 2.
Pharmacokinetics
Peak Effect: PO: 2 to 3 hours
Duration: 4 to 6 hours (IR); 12 hours (ER)
Storage and Handling
Store tablets, capsules, and liquid at controlled room temperature (15 to 30 degrees Celsius). Protect from moisture.
Reconstitution:
Tablets, capsules, and liquid require no reconstitution.
TCCC and TECC Role
Guaifenesin is not a TCCC trauma management agent but is useful in deployment medicine for managing productive cough from upper respiratory infection. The drug pairs with hydration to thin tenacious mucus and facilitate clearance. For operators with productive cough, guaifenesin supports the clearing of secretions rather than suppressing the cough reflex, which is the clinically appropriate approach when mucus must be cleared. The drug is non-sedating and does not impair operational capability.
Guaifenesin is the expectorant carried for the URI with productive cough that is not clearing effectively. The pairing with hydration is critical; without adequate water intake, guaifenesin cannot thin mucus. The drug works best when continued for a full course (3 to 7 days) rather than single doses. Combination products with dextromethorphan (Mucinex DM, Robitussin DM) are useful when both expectorant and antitussive effects are needed for mixed productive and nonproductive cough, but match the drug to the cough type before choosing.
Suppressing a productive cough with antitussives like dextromethorphan when guaifenesin and hydration would be more appropriate. Productive coughs serve a clearing function and should generally be supported, not suppressed. The other common error is administering guaifenesin without ensuring adequate hydration; the drug cannot thin dry mucus, and the patient must drink fluids for the expectorant effect to work.
This drug profile is provided as educational reference material for trained medical providers. It is not medical advice, not a substitute for formal training, and not a substitute for current published guidelines or medical direction.
Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances are subject to additional handling, accountability, and documentation requirements per DEA and state law. Always verify dosing, indications, contraindications, and route of administration against current published guidelines and your local protocols before administration.
If this content is being viewed during a medical emergency, call 911 immediately and follow the direction of your local emergency dispatch and medical control. Do not use this reference as a substitute for emergency medical services.
Drug information evolves. Last reviewed dates and source citations are provided for each entry. Confirm currency against the cited source before clinical use.
Penn Tactical Solutions publishes this reference for educational purposes. PTS does not provide medical direction and does not assume responsibility for clinical decisions made in the field. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Educational reference for trained medical providers. Not medical advice. Not a substitute for formal training, current published guidelines, or medical direction. Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances require additional storage, accountability, and documentation per DEA and state law.
In a medical emergency, call 911. This reference is not a substitute for emergency medical services.
Verify dosing, indications, and contraindications against current published guidelines and your local protocols before administration. Confirm content currency against the source citation. Penn Tactical Solutions does not provide medical direction. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Guaifenesin
| PO | Immediate release: 200 to 400 mg PO every 4 hours, maximum 2.4 g/day. Extended release (Mucinex): 600 to 1200 mg PO every 12 hours. (15 to 30 minutes) |