Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
HY-PHEN vs FLOWTUSS
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
HY-PHEN is a combination of hydrocodone (a mu-opioid receptor agonist) and acetaminophen (an analgesic and antipyretic). Hydrocodone binds to mu-opioid receptors in the CNS, altering pain perception and emotional response to pain. Acetaminophen inhibits cyclooxygenase (COX) enzymes, particularly in the CNS, reducing prostaglandin synthesis.
FLOWTUSS (guaifenesin) is an expectorant that increases respiratory tract fluid secretions, reducing mucus viscosity and facilitating clearance.
Management of moderate to moderately severe pain,Off-label: Acute pain, postoperative pain, chronic pain (limited use due to acetaminophen toxicity risk)
Relief of productive cough associated with respiratory tract infections,Chronic obstructive pulmonary disease (COPD) exacerbations,Cystic fibrosis (off-label)
1-2 tablets (acetaminophen 500 mg/hydrocodone 5-10 mg) orally every 4-6 hours as needed for pain; maximum 8 tablets per day.
10 mg orally every 4-6 hours as needed for cough; maximum 60 mg/day.
2-3 hours (terminal elimination half-life). Clinical context: Short half-life requires frequent dosing (every 4-6 hours) for sustained analgesic effect.
Terminal elimination half-life is 4–6 hours in adults with normal renal function; prolonged to 8–12 hours in moderate renal impairment (Cr Cl 30–50 m L/min).
Hydrocodone is metabolized via CYP3A4 to hydromorphone (active) and via CYP2D6 to norhydrocodone. Acetaminophen is primarily metabolized via glucuronidation and sulfation; a minor pathway via CYP2E1 produces a hepatotoxic metabolite (NAPQI) that is normally detoxified by glutathione.
Hepatic metabolism via oxidation and demethylation; primarily excreted renally as metabolites.
Renal (primarily as glucuronide conjugates and unchanged drug). Approximately 90-95% eliminated in urine within 24 hours; fecal excretion <5%.
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%).
25-35% bound to plasma proteins (mainly albumin).
85–90% bound to albumin and alpha-1-acid glycoprotein.
0.9-1.5 L/kg. Clinical meaning: Moderate Vd indicates distribution into total body water; does not extensively accumulate in tissues.
1.5–2.0 L/kg; indicates extensive tissue distribution (e.g., lungs, liver).
Oral: 60-90% (first-pass metabolism reduces systemic availability); Rectal: 70-80%; IV/IM: 100%.
Oral: 75–85% (first-pass metabolism accounts for 15–25% loss).
GFR 30-50 m L/min: administer at 75% of usual dose every 6 hours; GFR <30 m L/min: administer at 50% of usual dose every 8 hours. Avoid in severe renal impairment.
e GFR 30-60 m L/min: 5 mg every 6 hours; e GFR <30 m L/min: 5 mg every 8 hours.
Child-Pugh Class A: no adjustment; Class B: reduce dose by 50% and extend interval to every 8 hours; Class C: contraindicated.
Child-Pugh Class B: 5 mg every 6 hours; Child-Pugh Class C: 2.5 mg every 8 hours.
Not recommended for children under 18 years due to risk of opioid-related adverse effects; alternative analgesics preferred.
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.
Initiate with lowest effective dose (e.g., acetaminophen 500 mg/hydrocodone 5 mg) every 6 hours; monitor for respiratory depression, constipation, and falls; may require dose reduction by 25-50% compared to younger adults.
Initial dose 5 mg every 6 hours; increase cautiously due to increased risk of dizziness and sedation.
Addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion of acetaminophen (especially in children) can cause hepatotoxicity; neonatal opioid withdrawal syndrome with prolonged use during pregnancy; risks from concomitant use with benzodiazepines or other CNS depressants (additive respiratory depression).
None.
Hepatotoxicity due to acetaminophen (dose-dependent); respiratory depression (especially in elderly, debilitated, or COPD); opioid-induced hyperalgesia; adrenal insufficiency; severe hypotension; seizures; serotonin syndrome with serotonergic drugs; urinary retention; bile duct spasm; use in patients with head injury or increased intracranial pressure (risk of masking neurological signs); neonatal withdrawal syndrome.
Avoid use with persistent or chronic cough (e.g., smoking, asthma, COPD) unless directed by a physician. Use caution in patients with renal impairment.
Significant respiratory depression; acute or severe bronchial asthma; known or suspected gastrointestinal obstruction (e.g., paralytic ileus); severe hepatic impairment; hypersensitivity to hydrocodone, acetaminophen, or any component; use of MAO inhibitors within 14 days (hypertensive crisis).
Hypersensitivity to guaifenesin or any component; concurrent use with other expectorants.
Avoid alcohol consumption due to increased risk of hepatotoxicity and CNS depression. Grapefruit juice may inhibit CYP2D6 metabolism of hydrocodone, potentially altering analgesic effect; avoid concurrent use. High-fat meals may increase absorption of hydrocodone; take consistently with or without food.
No specific food interactions. Alcohol may increase CNS depressant effects (dizziness, sedation).
Pregnancy Category C. First trimester: No well-controlled studies; potential for fetal harm based on animal studies (cleft palate, skeletal anomalies). Second and third trimesters: Prolonged use may cause neonatal withdrawal syndrome (irritability, hypertonia, respiratory depression) if used near term. Avoid use in pregnancy unless benefit outweighs 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.
HY-PHEN (hydrocodone/acetaminophen) is excreted into breast milk in low concentrations. M/P ratio for hydrocodone is approximately 2.0, for acetaminophen ~1.0. Use caution; monitor infant for sedation, respiratory depression, and poor feeding. Consider risk of neonatal withdrawal if maternal use is chronic.
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.
No specific dose adjustments established for pregnancy. Increased plasma volume and enhanced hepatic metabolism in pregnancy may reduce drug concentrations, potentially requiring higher doses to achieve analgesic effect. However, avoid high doses due to risk of acetaminophen hepatotoxicity and fetal opioid exposure. Use lowest effective dose for shortest duration.
No standard dose adjustment recommended during pregnancy. Use lowest effective dose for shortest duration. Consider pharmacokinetic changes in pregnancy (increased clearance of dextromethorphan may require higher doses for efficacy, but safety limits apply).
HY-PHEN is a combination of hydrocodone and acetaminophen. Monitor for acetaminophen hepatotoxicity; maximum daily acetaminophen dose should not exceed 4 g from all sources. Hydrocodone is a prodrug metabolized by CYP2D6 to hydromorphone; poor metabolizers may have reduced analgesia while ultra-rapid metabolizers risk toxicity. Avoid concurrent use with other CNS depressants including alcohol due to additive respiratory depression. Taper dose when discontinuing after prolonged use to prevent withdrawal.
FLOWTUSS (guaifenesin) is an expectorant that increases respiratory tract fluid secretion, reducing mucus viscosity. Onset of action is 30-60 minutes. Maximum effect requires adequate hydration (8-10 glasses of water daily). Not recommended for chronic cough due to smoking, asthma, or emphysema. Avoid use in patients with persistent cough lasting >1 week or accompanied by fever, rash, or headache. May cause dizziness; caution when driving.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Do not take other products containing acetaminophen (e.g., Tylenol, cold medicines) while using this medication to avoid liver damage.,Avoid alcohol completely while taking this drug; it increases the risk of liver damage and severe drowsiness.,Do not drive or operate heavy machinery until you know how this medication affects you; it may cause dizziness or drowsiness.,Store securely away from children and others; misuse can cause addiction, overdose, or death.,Do not stop taking suddenly after long-term use; your doctor will help you taper off to prevent withdrawal symptoms.
Drink plenty of water to help loosen mucus.,Do not take more than 6 doses in 24 hours.,Discontinue and consult doctor if cough persists >7 days or if fever, rash, or headache develop.,Avoid alcohol; may increase dizziness.,Do not use for chronic cough from smoking or asthma without medical advice.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about HY-PHEN vs FLOWTUSS, answered by our medical review team.
HY-PHEN is a Opioid Antitussive Combination that works by HY-PHEN is a combination of hydrocodone (a mu-opioid receptor agonist) and acetaminophen (an analgesic and antipyretic). Hydrocodone binds to mu-opioid receptors in the CNS, altering pain perception and emotional response to pain. Acetaminophen inhibits cyclooxygenase (COX) enzymes, particularly in the CNS, reducing prostaglandin synthesis.. FLOWTUSS is a Expectorant that works by FLOWTUSS (guaifenesin) is an expectorant that increases respiratory tract fluid secretions, reducing mucus viscosity and facilitating clearance.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between HY-PHEN and FLOWTUSS depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of HY-PHEN is: 1-2 tablets (acetaminophen 500 mg/hydrocodone 5-10 mg) orally every 4-6 hours as needed for pain; maximum 8 tablets per day.. The standard adult dose of FLOWTUSS is: 10 mg orally every 4-6 hours as needed for cough; maximum 60 mg/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between HY-PHEN and FLOWTUSS in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. HY-PHEN is classified as Category C. Pregnancy Category C. First trimester: No well-controlled studies; potential for fetal harm based on animal studies (cleft palate, skeletal anomalies). Second and third trimesters:. FLOWTUSS is classified as Category C. FLOWTUSS contains guaifenesin and dextromethorphan. Guaifenesin is FDA pregnancy category C; animal studies show fetal abnormalities at high doses, but human data insufficient. Dex. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.