Common Dextromethorphan-Containing Cough Syrups and Their Compositions
Dextromethorphan is the preferred antitussive for dry cough, available in numerous over-the-counter preparations at varying concentrations, though most contain subtherapeutic doses below the optimal 60 mg needed for maximum cough suppression. 1
Common Brand Names and Formulations
Single-Ingredient Dextromethorphan Products
- Delsym (Extended-Release): Contains dextromethorphan polistirex equivalent to 30 mg dextromethorphan hydrobromide per 5 mL, providing 12-hour cough relief 2
- Robitussin for Dry Coughs: Contains dextromethorphan as the primary active ingredient 3
Combination Products with Dextromethorphan
- Benylin Dry Coughs: Contains dextromethorphan in combination formulations 3
- Benylin Tickly Coughs: Contains dextromethorphan 3
- Actifed Multi-Action Dry Coughs: Contains dextromethorphan 3
- Meltus Dry Coughs: Contains dextromethorphan 3
- Day & Night Nurse (GSK): Contains dextromethorphan plus pholcodine 3
- Alex Syrup: Contains chlorpheniramine maleate 4 mg + dextromethorphan 20 mg + phenylephrine 10 mg per dose 4
- Bilastine/Dextromethorphan/Phenylephrine combinations: Contains bilastine 6.6 mg + dextromethorphan 20 mg + phenylephrine 10 mg 4
Critical Dosing Information
Standard Dosing
- Recommended dose: 10-15 mg three to four times daily, with maximum daily dose of 120 mg 5
- Optimal therapeutic dose: 60 mg for maximum cough reflex suppression 1, 5
- Standard over-the-counter preparations are often subtherapeutic, containing doses below the 60 mg needed for optimal effect 1, 6
Important Safety Warnings
- Many combination products contain additional ingredients such as acetaminophen, antihistamines, or decongestants that can cause toxicity at higher doses 1, 7
- Always check combination products carefully to avoid excessive amounts of other ingredients when using higher dextromethorphan doses 5
- Delsym contains sodium metabisulfite, which may cause allergic-type reactions in susceptible individuals 2
Composition Variations by Product Type
Dextromethorphan + Antihistamine Combinations
- First-generation antihistamines (chlorpheniramine) are commonly combined with dextromethorphan for nocturnal cough due to sedative effects 8, 4
- Non-sedating antihistamines (bilastine) provide cough relief without drowsiness 4
Dextromethorphan + Decongestant Combinations
- Phenylephrine is frequently combined with dextromethorphan for cough associated with nasal congestion 4
Glycerol-Based Alternatives
- Sinecod (butamirate citrate): Showed cough reduction in trials, available over-the-counter in some regions 3, 5
- Multiple glycerol-based preparations offer low cost with favorable side effect profiles 5
Geographic Availability Considerations
- Some formulations are not available in the United States and other countries, with regional variations in product availability 3
- Pure dextromethorphan powder is available through internet sources in multiples of 1 gram, though this carries significant abuse potential 7
Key Clinical Pitfall
The most common prescribing error is using subtherapeutic doses of dextromethorphan (less than 60 mg) that provide inadequate cough suppression. 1, 6