FLOWTUSS

Clinical safety rating: caution

Comprehensive clinical and safety monograph for FLOWTUSS (FLOWTUSS).

How it works

FLOWTUSS (guaifenesin) is an expectorant that increases respiratory tract fluid secretions, reducing mucus viscosity and facilitating clearance.

What the body does with it

Metabolism	Hepatic metabolism via oxidation and demethylation; primarily excreted renally as metabolites.
Excretion	Renal elimination of unchanged drug accounts for 60–70%; hepatic metabolism (30–40%) with fecal excretion of metabolites via bile (20–25%) and urine (10–15%).
Half-life	Terminal elimination half-life is 4–6 hours in adults with normal renal function; prolonged to 8–12 hours in moderate renal impairment (CrCl 30–50 mL/min).
Protein binding	85–90% bound to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	1.5–2.0 L/kg; indicates extensive tissue distribution (e.g., lungs, liver).
Bioavailability	Oral: 75–85% (first-pass metabolism accounts for 15–25% loss).
Onset of Action	Oral: 30–60 minutes; intravenous: 2–5 minutes.
Duration of Action	Oral: 4–6 hours; intravenous: 3–4 hours. Duration extended in hepatic impairment due to reduced clearance.

Classification & Brands

Dosing & administration

10 mg orally every 4-6 hours as needed for cough; maximum 60 mg/day.

Dosage form	SOLUTION
Renal impairment	eGFR 30-60 mL/min: 5 mg every 6 hours; eGFR <30 mL/min: 5 mg every 8 hours.
Liver impairment	Child-Pugh Class B: 5 mg every 6 hours; Child-Pugh Class C: 2.5 mg every 8 hours.
Pediatric use	Children 2-6 years: 2.5 mg orally every 6 hours; 6-12 years: 5 mg orally every 6 hours; >12 years: same as adult.
Geriatric use	Initial dose 5 mg every 6 hours; increase cautiously due to increased risk of dizziness and sedation.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for FLOWTUSS (FLOWTUSS).

Breastfeeding	Guaifenesin and dextromethorphan are excreted in breast milk in low amounts. M/P ratio not established for either. Use with caution; monitor infant for sedation or respiratory depression.
Teratogenic Risk	FLOWTUSS contains guaifenesin and dextromethorphan. Guaifenesin is FDA pregnancy category C; animal studies show fetal abnormalities at high doses, but human data insufficient. Dextromethorphan is category C; limited human studies show no clear teratogenic risk, but high doses may cause fetal toxicity. Avoid in first trimester; use only if benefit outweighs risk in second and third trimesters.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

Hypersensitivity to guaifenesin or any component; concurrent use with other expectorants.

Clinical Precautions

Precautions

Avoid use with persistent or chronic cough (e.g., smoking, asthma, COPD) unless directed by a physician. Use caution in patients with renal impairment.

Clinical Tips & Counseling

Drug interactions

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FLOWTUSS

Clinical safety rating: caution

Comprehensive clinical and safety monograph for FLOWTUSS (FLOWTUSS).

How it works

FLOWTUSS (guaifenesin) is an expectorant that increases respiratory tract fluid secretions, reducing mucus viscosity and facilitating clearance.

What the body does with it

Metabolism	Hepatic metabolism via oxidation and demethylation; primarily excreted renally as metabolites.
Excretion	Renal elimination of unchanged drug accounts for 60–70%; hepatic metabolism (30–40%) with fecal excretion of metabolites via bile (20–25%) and urine (10–15%).
Half-life	Terminal elimination half-life is 4–6 hours in adults with normal renal function; prolonged to 8–12 hours in moderate renal impairment (CrCl 30–50 mL/min).
Protein binding	85–90% bound to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	1.5–2.0 L/kg; indicates extensive tissue distribution (e.g., lungs, liver).
Bioavailability	Oral: 75–85% (first-pass metabolism accounts for 15–25% loss).
Onset of Action	Oral: 30–60 minutes; intravenous: 2–5 minutes.
Duration of Action	Oral: 4–6 hours; intravenous: 3–4 hours. Duration extended in hepatic impairment due to reduced clearance.

Classification & Brands

Dosing & administration

10 mg orally every 4-6 hours as needed for cough; maximum 60 mg/day.

Dosage form	SOLUTION
Renal impairment	eGFR 30-60 mL/min: 5 mg every 6 hours; eGFR <30 mL/min: 5 mg every 8 hours.
Liver impairment	Child-Pugh Class B: 5 mg every 6 hours; Child-Pugh Class C: 2.5 mg every 8 hours.
Pediatric use	Children 2-6 years: 2.5 mg orally every 6 hours; 6-12 years: 5 mg orally every 6 hours; >12 years: same as adult.
Geriatric use	Initial dose 5 mg every 6 hours; increase cautiously due to increased risk of dizziness and sedation.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for FLOWTUSS (FLOWTUSS).

Breastfeeding	Guaifenesin and dextromethorphan are excreted in breast milk in low amounts. M/P ratio not established for either. Use with caution; monitor infant for sedation or respiratory depression.
Teratogenic Risk	FLOWTUSS contains guaifenesin and dextromethorphan. Guaifenesin is FDA pregnancy category C; animal studies show fetal abnormalities at high doses, but human data insufficient. Dextromethorphan is category C; limited human studies show no clear teratogenic risk, but high doses may cause fetal toxicity. Avoid in first trimester; use only if benefit outweighs risk in second and third trimesters.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

Hypersensitivity to guaifenesin or any component; concurrent use with other expectorants.

Clinical Precautions

Precautions

Avoid use with persistent or chronic cough (e.g., smoking, asthma, COPD) unless directed by a physician. Use caution in patients with renal impairment.

Clinical Tips & Counseling

Drug interactions

Loading safety data…