Guaifenesin

MUCINEX

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Pronunciation: gwye-FEN-e-sin

Guaifenesin ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Guaifenesin ballicule

Guaifenesin MUCINEX mascot mnemonic cartoon — Visual mnemonic: Guaifenesin mascot
**“Mucin, next Guy fencin’”**

What it isExpectorant with incidental NMDA antagonism and an otherwise uncertain target; cough with thick secretions.

Why this oneThe only widely used oral expectorant, but its popularity greatly exceeds the strength of its evidence.

What limits itBenefit is often indistinguishable from hydration; stop if there is no clear response rather than escalating combination products.

Guaifenesin molecular structure (skeletal formula) — Molecular structure: Guaifenesin

FDA-approved for

cough (expectorant) (~1952)

Principal riskLittle

Classes and tags

Clinical profile

Therapeutic safety burden1 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryNot assigned — OTC/monograph

Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.

FDA label

Read the full label on DailyMed ↗

NO BOXED WARNINGS

FDA dosing	Population	Start	Target	Max
Expectorant (OTC Uses): helps loosen phlegm (mucus) and thin bronchial secretions to rid the bronchial passageways of bothersome mucus and make coughs more productive	Adults and children >=12 y	1 or 2 ER tablets (600 mg each) q12h	1 or 2 ER tablets (600 mg each) q12h	4 ER tablets per 24 h
Expectorant (OTC Uses): helps loosen phlegm (mucus) and thin bronchial secretions to rid the bronchial passageways of bothersome mucus and make coughs more productive	Children <12 y	Do not use	Do not use	Do not use

Renal Undefined

Hepatic Undefined

Do not exceed 4 tablets in 24 hours.

Instructions

Do not crush, chew, or break the tablet.
Take with a full glass of water.
May be taken with or without meals.
Do not use in children under 12 years.

Available strengths

ER tab 600, 1200 mg
tab 200, 400, 600, 1200 mg
sol 200, 400 mg/10 mL
sol 300 mg/15 mL
sol 50 mg/2.5 mL
sol 100 mg/5 mL

Pregnancy Undefined

Lactation Undefined

Cost

Guaifenesin (MUCINEX)

What pharmacies pay · NADAC 9/30/26 · OTC

Strength		#/mo	generic $/mo	CostPlus
600 mg	ER tab	60 BID	$17.04	out of stock
1200 mg	ER tab	60 BID	$25.90	not offered

Generic entryPre-1982

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Self-check

How does guaifenesin’s popularity compare with its evidence?
Popularity greatly exceeds evidence strength.
What should happen if guaifenesin has no clear benefit?
Stop it.