Over-the-Counter Brompheniramine + Sustained-Release Pseudoephedrine Products
For adults without contraindications, the recommended regimen is brompheniramine 12 mg combined with sustained-release pseudoephedrine 120 mg taken twice daily (every 12 hours). 1
Available Formulations
Brompheniramine 12 mg + sustained-release pseudoephedrine 120 mg is the evidence-based combination specifically studied and recommended by the American College of Chest Physicians for upper airway cough syndrome and allergic rhinitis. 1
This combination is available as a sustained-release tablet formulation designed for twice-daily dosing (morning and evening, approximately 12 hours apart). 1, 2
Common brand names include various generic formulations; the specific product "Dimetapp DM" mentioned in your question typically contains dextromethorphan (a cough suppressant) rather than the pure brompheniramine-pseudoephedrine combination, so verify the exact formulation on the label. 3
Adult Dosing Schedule
Standard adult dose: One tablet (brompheniramine 12 mg + pseudoephedrine 120 mg sustained-release) every 12 hours. 1
Maximum duration: Limit use to the shortest necessary period, typically 3–7 days for acute symptoms; chronic use beyond 2 weeks without medical supervision is not recommended. 1, 4
Initiation strategy to minimize sedation: Start with once-daily dosing at bedtime for 2–3 days, then advance to twice-daily dosing if tolerated. 1
Absolute Contraindications
Before recommending this combination, screen for the following conditions that prohibit use:
Severe or uncontrolled hypertension – pseudoephedrine raises systolic blood pressure by approximately 1 mmHg on average, but individual responses vary widely and can trigger dangerous hypertensive spikes. 5
Symptomatic benign prostatic hypertrophy or urinary retention – the anticholinergic properties of brompheniramine worsen these conditions. 1
Narrow-angle glaucoma – anticholinergic effects increase intraocular pressure. 1, 4
Congestive heart failure or severe coronary artery disease – pseudoephedrine's vasoconstrictive effects can precipitate cardiac decompensation. 5
Concurrent monoamine oxidase inhibitor (MAOI) therapy – this combination can trigger hypertensive crisis. 5
Children younger than 6 years – serious adverse events including 69 antihistamine-related deaths (41 in children under 2 years) and 54 decongestant-related deaths were documented between 1969 and 2006; the FDA advises against use in this age group. 4
Relative Contraindications Requiring Monitoring
Controlled hypertension: May use with caution if blood pressure is monitored within 24–48 hours of initiation; discontinue immediately if systolic BP rises >20 mmHg or new symptoms develop. 5
Concurrent stimulant medications (e.g., methylphenidate for ADHD): The combination creates additive cardiovascular burden; if unavoidable, monitor BP and heart rate closely and limit decongestant use to 3–5 days maximum. 4
Hyperthyroidism, arrhythmias, or cerebrovascular disease: Use only if safer alternatives (intranasal corticosteroids, saline irrigation) are ineffective. 5, 4
Common Pitfalls to Avoid
Do not substitute second-generation antihistamines (cetirizine, loratadine, fexofenadine) for brompheniramine in this indication; they lack the anticholinergic properties necessary to reduce secretions and suppress cough in upper airway cough syndrome. 1
Do not combine with other sympathomimetic agents (caffeine, energy drinks, additional decongestants, or stimulants) because this substantially increases the risk of hypertensive crisis. 5, 4
Do not use for viral upper respiratory infections in otherwise healthy adults—European and American guidelines explicitly advise against antihistamines for post-viral rhinosinusitis because viral infections are not histamine-mediated; safer alternatives include analgesics, high-volume saline irrigation (≥150 mL), and intranasal corticosteroids. 1
Avoid NSAIDs (ibuprofen, naproxen) in combination products if the patient has hypertension, as NSAIDs can raise BP by an additional 3 mmHg systolic and blunt antihypertensive medications. 5
Safer Alternatives When Contraindications Exist
Intranasal corticosteroids (e.g., fluticasone 100–200 µg daily) have no cardiovascular effects and are the preferred first-line option for patients with hypertension or cardiac disease. 1, 5
High-volume nasal saline irrigation (≥150 mL) provides mechanical clearance with no systemic absorption. 1, 5
Second-generation antihistamines alone (loratadine, cetirizine, fexofenadine) are safe in hypertensive patients but are ineffective for upper airway cough syndrome; reserve them for allergic rhinitis without cough. 1, 5
Expected Clinical Response
Symptom improvement typically occurs within a few days to 2 weeks of starting therapy. 1
If no improvement after 2 weeks of adequate therapy, obtain sinus imaging (CT or radiographs) to evaluate for chronic sinusitis, and consider alternative diagnoses such as asthma, non-asthmatic eosinophilic bronchitis, or gastroesophageal reflux disease. 1