[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Cough and cold medicines](https://durgical.com/en/pharmacology/classes/cough-and-cold-medicines/) › Guaifenesin

# Guaifenesin

## Cough and cold medicines?

Cough and cold medicines

An expectorant that thins mucus so it is easier to cough up; it relieves chest congestion but does not treat the cause.

Updated Nov 1, 2026

Also called: Glyceryl guaiacolate

## Quick facts

**Group**
[Cough and cold medicines](https://durgical.com/en/pharmacology/classes/cough-and-cold-medicines/)

**Target**
Airway secretions (expectorant action)

**Used for**
Loosening mucus · Productive cough of acute bronchitis

**Key effects**
Nausea and vomiting · Dizziness and headache · Rash

**Monitor**
Character of sputum and ease · Fever or breathlessness

**ATC**
R05CA03

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

Guaifenesin is thought to increase the volume and reduce the stickiness of airway secretions, partly through a reflex from the stomach that increases bronchial gland secretion. Thinner mucus is moved more easily by cilia and cough. It does not suppress cough, and the evidence for clinical benefit is modest.

- Guaifenesin stimulates a reflex from the stomach
- Bronchial glands secrete more watery fluid
- Mucus becomes thinner and less sticky
- Cough and cilia clear it more easily

## Indications

- Loosening mucus in chest congestion from colds and acute bronchitis [Common cold (acute viral rhinopharyngitis) →](https://durgical.com/en/conditions/common-cold/)
- Productive cough of acute bronchitis [Acute bronchitis →](https://durgical.com/en/conditions/acute-bronchitis/)

## Adverse effects

### Common

- Nausea and vomiting
- Dizziness and headache
- Rash (rare)

### Serious (rare, important)

- Serious effects or death in young children with cough and cold products
- Kidney stones with heavy misuse

## Contraindications

- Hypersensitivity to guaifenesin
- Children under 4 years with non-prescription products
- Cough lasting more than a week, or with fever, rash or headache, needs medical review rather than self-treatment

## Key interactions

**Combination products with dextromethorphan or decongestants**
Each added ingredient brings its own interactions and duplication risk

## What is monitored

- Character of sputum and ease of coughing it up
- Fever or breathlessness that suggest pneumonia

## Administration and safety

- Oral tablets (including extended-release, swallowed whole) and syrups
- Taken with a full glass of water; good hydration helps thin mucus

## Pregnancy and breastfeeding

Data are limited, especially for the first trimester; use is decided with the clinician.

## Nursing care

- Encourage fluids
- Teach that a cough with fever, rash or headache, or lasting more than a week, needs review
- Check combination products for duplicated ingredients

## Pharmacokinetics

**Absorption**
Well absorbed by mouth

**Metabolism**
Liver

**Elimination**
Urine, as metabolites

## Memory aid

GUAIfenesin: Gets Up All the phlegm: thins mucus, does not stop cough.

## Test yourself

Think of the answer, then tap the question to see it.

## Is guaifenesin a cough suppressant?

No; it is an expectorant that thins mucus.

## Below which age are non-prescription guaifenesin products not given?

Under 4 years.

## Which simple measure supports the effect of an expectorant?

Good fluid intake.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/guaifenesin/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 2

- [Dextromethorphan](https://durgical.com/en/pharmacology/dextromethorphan/)
- [Benzonatate](https://durgical.com/en/pharmacology/benzonatate/)

## Related conditions 2

- [Common cold (acute viral rhinopharyngitis)](https://durgical.com/en/conditions/common-cold/)
- [Acute bronchitis](https://durgical.com/en/conditions/acute-bronchitis/)

[← Back to the class: Cough and cold medicines](https://durgical.com/en/pharmacology/classes/cough-and-cold-medicines/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Guaifenesin: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682494.html) (MedlinePlus (U.S. National Library of Medicine), 2022); [Use Caution When Giving Cough and Cold Products to Kids | FDA](https://www.fda.gov/drugs/safe-use-over-counter-otc-medicines-children/use-caution-when-giving-cough-and-cold-products-kids) (U.S. Food and Drug Administration, 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=R05CA03) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/guaifenesin/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/guaifenesin/