Drug reference

Guaifenesin

Expectorant (mucolytic) · Cough medicine

START

200–400 mg PO every 4 h (or ER 600–1200 mg q12h)

TYPICAL MAX

2400 mg/day

STOP IF

Allergic reaction or persistent cough beyond 1 week

WATCH

Re-evaluate persistent cough beyond 1 week

CDSCO approvedOTCATC R05CA03

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 15min · absorption
PEAK: 30min · Tmax
t½: 1h · t½
DURATION: 4h · per dose

EXCRETION

Renal — metabolites

route + CYP

INTERACTIONS

—

none in our sources

PREGNANCY

Considered acceptable in pregnancy.

FDA category + note

Mechanism

Reduces respiratory secretion viscosity by stimulating gastric reflex secretion of bronchial fluid; mild mucolytic action thins mucus and facilitates expectoration in productive cough.

Indications

Symptomatic relief of productive cough associated with respiratory infections

Dosing

Adult: 200–400 mg PO every 4 h; ER 600–1200 mg PO every 12 h. Max 2400 mg/day.
Pediatric: 2–6 y: 50–100 mg every 4 h. 6–12 y: 100–200 mg every 4 h.
Renal adjustment: No fixed adjustment.
Hepatic adjustment: No fixed adjustment.
Geriatric: Standard dose.
Max dose: 2400 mg/day

Pharmacokinetics

Onset

Expectorant effect within hours

Peak effect

~15–30 min (Tmax)

Duration

~4 h (IR); ~12 h (ER)

Half-life

~1 h

Bioavailability

Well absorbed orally

Protein binding

Low

Metabolism

Hepatic

Excretion

Renal (metabolites)

Contraindications

Hypersensitivity
Caution: persistent cough (chronic, smoking, asthma) — evaluate cause

Side effects

Common

Generally well toleratedNausea / vomiting (high dose)HeadacheDrowsinessRash (rare)

Serious

Allergic reactions (rare)
Renal calculi (rare, with extensive use)

Pregnancy & lactation

Pregnancy

Considered acceptable in pregnancy.

Lactation

Compatible at recommended doses.

Drug interactions

Mao Inhibitors

Moderate

Database

MAOI + decongestant (if combo product)

Avoid combo cold products with sympathomimetics + MAOI