Please write a prescription order for Mucinex DM (guaifenesin 600 mg + dextromethorphan 30 mg) for a patient aged 12 years or older with a productive cough.

Prescription Order for Mucinex DM

For a patient aged 12 years or older with productive cough, prescribe Mucinex DM (guaifenesin 600 mg + dextromethorphan 30 mg extended-release tablets): Take 1 tablet by mouth every 12 hours with a full glass of water, not to exceed 2 tablets in 24 hours, for up to 7 days. 1

Dosing Instructions

• One tablet every 12 hours (maximum 2 tablets per 24 hours)
• Swallow whole—do not crush, chew, or break the tablet
• Take with a full glass of water
• Can be taken without regard to meals
• Duration: Maximum 7 days—if cough persists beyond this, patient must return for re-evaluation 1

Age Restrictions

• Only for patients 12 years and older
• Do not use in children under 12 years of age 1

Contraindications and Warnings

Absolute contraindications:

• Current use of MAO inhibitors (MAOIs) or within 2 weeks of stopping MAOI therapy 1
• Age under 12 years 1

Relative contraindications—consult before prescribing:

• Persistent or chronic cough from smoking, asthma, chronic bronchitis, or emphysema
• Cough with excessive phlegm production 1

Stop Medication and Seek Medical Attention If:

• Cough lasts more than 7 days
• Cough returns after improvement
• Fever, rash, or persistent headache develops (may indicate serious illness) 1

Clinical Context

The dextromethorphan component (30 mg) provides cough suppression. Guidelines indicate that maximum cough reflex suppression occurs at 60 mg, and standard OTC dosing may be subtherapeutic 2. However, the extended-release formulation in Mucinex DM provides sustained therapeutic levels over 12 hours 1.

Important caveat: While dextromethorphan has demonstrated cough suppression in meta-analyses 2, the evidence for guaifenesin as an expectorant remains limited. Recent reviews question its efficacy over placebo 3, and when combined with cough suppressants like dextromethorphan, there is theoretical risk of increased airway obstruction if secretions are retained 4. Despite this, the combination remains widely used and FDA-approved 1.

Safety Profile

Both components have well-established safety profiles in adults and pediatric populations (≥12 years) 5, 6. The extended-release formulation provides convenience with twice-daily dosing 6.

Pregnancy/breastfeeding: Advise patient to consult healthcare professional before use 1