Guaifenesin
Guaifenesin is an expectorant medication that helps relieve chest congestion by thinning and loosening mucus in the airways, making it easier to clear through coughing. It is commonly used to treat symptoms of colds, flu, bronchitis, and other respiratory conditions where excess mucus causes discomfort.
Guaifenesin is an over-the-counter expectorant that helps clear chest congestion by loosening and thinning mucus.
Key facts at a glance
- ATC
- R05CA03
- RxNorm
- 5032
- Generic
- Guaifenesin
- Class
- atc-r05
- Brands
- Refenesen, Cough Out, Kids-Eeze Chest Relief, Rompe Pecho, Lortuss EX, Zodryl DEC, Ninjacof XG, Obredon, Hycofenix, Bidex, Bronkaid, Brontex, Liquibid, Robafen, Scot-Tussin
- Availability
- otc
- Pregnancy
- C
- Lactation
- caution
- Half-life (h)
- 1
- Onset (min)
- 30
- Duration (h)
- 6
- Routes
- oral
- Forms
- tablet, extended-release tablet, capsule, syrup, oral solution, granules
- Regions
- United States, Canada, United Kingdom, European Union, Australia, Japan, India, Brazil
- Monitoring
- none
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
8 groupspregnancy
first trimesteravoid if possible
avoid use during first trimester unless benefits outweigh risks
regular prenatal monitoring
Use with caution and monitor for adverse effects.
pregnancy
second trimesteruse lowest effective dose
use only if clearly needed
standard prenatal care
Use with caution and monitor for adverse effects.
pregnancy
third trimesteravoid close to delivery
avoid use near term unless necessary
fetal monitoring in late pregnancy
Use with caution and monitor for adverse effects.
lactation
breastfeedingno adjustment needed
generally considered compatible with breastfeeding
monitor infant for unusual drowsiness
geriatric
elderlyno adjustment needed
use standard adult dosing, monitor for dizziness
standard geriatric monitoring
pediatric_age
children 2 12 yearsweight-based dosing required
use pediatric formulation, do not exceed recommended dose
monitor for side effects
Use with caution and monitor for adverse effects.
renal_impairment
mild to moderateno adjustment needed
standard dosing acceptable
standard renal function monitoring
hepatic_impairment
mild to moderateno adjustment needed
standard dosing acceptable
standard hepatic function monitoring
Statistics and clinical data
Commonly prescribed since
General prescribing information
Drug class
Drug class information
Common uses
Common therapeutic uses
Mechanism of action
Pharmacological action
Used to temporarily relieve chest congestion and cough due to the common cold, flu, bronchitis, and other respiratory infections. It helps break up mucus so it can be more easily expelled.
Guaifenesin works by increasing the water content in respiratory secretions, which thins and loosens thick mucus in the airways. This makes it easier to cough out congestion.
Should be taken with plenty of water. Not recommended for persistent cough due to smoking, asthma, or emphysema unless directed by a physician. Consult a healthcare provider before use if pregnant, breastfeeding, or giving to children under 4 years old.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
WellAlly may earn a referral fee from linked resources at no extra cost to you. Editorial content is never influenced by commercial relationships.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 26, 2026. · Read our editorial policy