MUCINEX DM

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MUCINEX DM (MUCINEX DM).

How it works

Guaifenesin increases respiratory tract fluid secretion to reduce mucus viscosity; dextromethorphan acts on sigma-1 receptors and NMDA receptor antagonism to suppress cough reflex.

What the body does with it

Metabolism	Guaifenesin undergoes hepatic metabolism via oxidation and conjugation; dextromethorphan is metabolized by CYP2D6 to dextrorphan, an active metabolite.
Excretion	Guaifenesin: renal (primarily as inactive metabolites, <1% unchanged). Dextromethorphan: renal (as unchanged drug and metabolites, including dextrorphan). Approximately 80% eliminated in urine as metabolites.
Half-life	Guaifenesin: 1-3 hours. Dextromethorphan: 3-30 hours depending on CYP2D6 phenotype; extensive metabolizers 3-8 hours, poor metabolizers 15-30 hours.
Protein binding	Guaifenesin: approximately 30% to albumin. Dextromethorphan: approximately 50% to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	Guaifenesin: 0.8-1.5 L/kg. Dextromethorphan: 5-10 L/kg (extensive tissue binding).
Bioavailability	Oral: Guaifenesin ~100% (tablet/syrup). Dextromethorphan ~11% (extensive first-pass metabolism; varies with CYP2D6 phenotype).
Onset of Action	Oral: Guaifenesin 30 minutes; Dextromethorphan 15-30 minutes.
Duration of Action	Guaifenesin: 4-6 hours. Dextromethorphan: 3-6 hours for antitussive effect.

Classification & Brands

Dosing & administration

One tablet (guaifenesin 600 mg / dextromethorphan HBr 30 mg) orally every 12 hours, not to exceed 2 tablets in 24 hours.

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	CrCl 30-50 mL/min: administer every 24 hours. CrCl <30 mL/min: not recommended. Hemodialysis: not recommended. Peritoneal dialysis: not recommended.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50% or extend interval to every 24 hours. Child-Pugh C: not recommended.
Pediatric use	Children ≥12 years: same as adult. Children 6-11 years: guaifenesin 300 mg / dextromethorphan 15 mg orally every 12 hours, not to exceed 2 doses in 24 hours. Children <6 years: not recommended.
Geriatric use	Start at lower end of dosing range (e.g., one tablet every 24 hours) due to age-related renal and hepatic decline; monitor for CNS effects and constipation.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MUCINEX DM (MUCINEX DM).

Breastfeeding	Guaifenesin: excreted into breast milk in small amounts; no known adverse effects in infants at maternal therapeutic doses. Dextromethorphan: likely excreted into breast milk in low concentrations; M/P ratio not established. Use caution; monitor infant for sedation, respiratory depression, or constipation.
Teratogenic Risk	FDA Category C for guaifenesin and dextromethorphan. First trimester: limited human data; animal studies show no evidence of teratogenicity at clinically relevant doses. Second and third trimesters: no known fetal risks at recommended doses. Avoid high doses of dextromethorphan due to potential serotonin reuptake inhibition and theoretical risk of fetal serotonin syndrome.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Concomitant use with MAOIs or within 14 days of MAOI therapy","Hypersensitivity to any component"]

Clinical Precautions

Precautions

["Do not use for persistent/chronic cough, cough with excessive phlegm, or cough due to smoking/asthma/COPD/emphysema","Serotonin syndrome risk with MAOIs or other serotonergic drugs","Dextromethorphan abuse potential","Hypersensitivity reactions"]

Clinical Tips & Counseling

Drug interactions

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MUCINEX DM

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MUCINEX DM (MUCINEX DM).

How it works

Guaifenesin increases respiratory tract fluid secretion to reduce mucus viscosity; dextromethorphan acts on sigma-1 receptors and NMDA receptor antagonism to suppress cough reflex.

What the body does with it

Metabolism	Guaifenesin undergoes hepatic metabolism via oxidation and conjugation; dextromethorphan is metabolized by CYP2D6 to dextrorphan, an active metabolite.
Excretion	Guaifenesin: renal (primarily as inactive metabolites, <1% unchanged). Dextromethorphan: renal (as unchanged drug and metabolites, including dextrorphan). Approximately 80% eliminated in urine as metabolites.
Half-life	Guaifenesin: 1-3 hours. Dextromethorphan: 3-30 hours depending on CYP2D6 phenotype; extensive metabolizers 3-8 hours, poor metabolizers 15-30 hours.
Protein binding	Guaifenesin: approximately 30% to albumin. Dextromethorphan: approximately 50% to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	Guaifenesin: 0.8-1.5 L/kg. Dextromethorphan: 5-10 L/kg (extensive tissue binding).
Bioavailability	Oral: Guaifenesin ~100% (tablet/syrup). Dextromethorphan ~11% (extensive first-pass metabolism; varies with CYP2D6 phenotype).
Onset of Action	Oral: Guaifenesin 30 minutes; Dextromethorphan 15-30 minutes.
Duration of Action	Guaifenesin: 4-6 hours. Dextromethorphan: 3-6 hours for antitussive effect.

Classification & Brands

Dosing & administration

One tablet (guaifenesin 600 mg / dextromethorphan HBr 30 mg) orally every 12 hours, not to exceed 2 tablets in 24 hours.

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	CrCl 30-50 mL/min: administer every 24 hours. CrCl <30 mL/min: not recommended. Hemodialysis: not recommended. Peritoneal dialysis: not recommended.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50% or extend interval to every 24 hours. Child-Pugh C: not recommended.
Pediatric use	Children ≥12 years: same as adult. Children 6-11 years: guaifenesin 300 mg / dextromethorphan 15 mg orally every 12 hours, not to exceed 2 doses in 24 hours. Children <6 years: not recommended.
Geriatric use	Start at lower end of dosing range (e.g., one tablet every 24 hours) due to age-related renal and hepatic decline; monitor for CNS effects and constipation.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MUCINEX DM (MUCINEX DM).

Breastfeeding	Guaifenesin: excreted into breast milk in small amounts; no known adverse effects in infants at maternal therapeutic doses. Dextromethorphan: likely excreted into breast milk in low concentrations; M/P ratio not established. Use caution; monitor infant for sedation, respiratory depression, or constipation.
Teratogenic Risk	FDA Category C for guaifenesin and dextromethorphan. First trimester: limited human data; animal studies show no evidence of teratogenicity at clinically relevant doses. Second and third trimesters: no known fetal risks at recommended doses. Avoid high doses of dextromethorphan due to potential serotonin reuptake inhibition and theoretical risk of fetal serotonin syndrome.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Concomitant use with MAOIs or within 14 days of MAOI therapy","Hypersensitivity to any component"]