Robitussin Active Ingredients
The primary active ingredient in Robitussin cough suppressant formulations is dextromethorphan, typically present as dextromethorphan hydrobromide or dextromethorphan polistirex (extended-release form). 1
Primary Active Ingredient
- Dextromethorphan is a non-sedating, centrally-acting cough suppressant that works by suppressing the cough reflex in the brainstem 2, 3
- Standard formulations contain dextromethorphan hydrobromide as the active ingredient 1
- Extended-release formulations (such as Delsym-type products) contain dextromethorphan polistirex equivalent to 30 mg dextromethorphan hydrobromide per 5 mL 1
Additional Ingredients in Combination Products
- Some Robitussin formulations combine dextromethorphan with guaifenesin (an expectorant), though guaifenesin has no proven efficacy for treating any form of lung disease 4, 5
- Certain products may contain antihistamines (such as diphenhydramine) or pseudoephedrine (a decongestant) in multi-symptom formulations 6
- Combination products with cough suppressants and expectorants carry potential risk of increased airway obstruction and should be avoided 5
Clinical Efficacy of Dextromethorphan
- Dextromethorphan demonstrates effectiveness in chronic bronchitis and COPD, reducing cough counts by 40-60% 4
- The drug shows limited efficacy (less than 20% suppression) for cough due to upper respiratory infections, requiring larger patient populations to demonstrate significant effects 4
- Maximum cough reflex suppression occurs at 60 mg, which is higher than standard over-the-counter dosing 2, 3
- Standard OTC dosing is often subtherapeutic for optimal cough suppression 2, 3
Safety Profile
- Dextromethorphan has a superior safety profile compared to codeine, with fewer adverse effects and no greater efficacy disadvantage 2, 3
- Adverse reactions are infrequent and usually not severe, predominantly including dose-related neurological, cardiovascular, and gastrointestinal disturbances 7
- Caution is required with higher doses as some combination preparations contain additional ingredients like acetaminophen (paracetamol) 2
- The drug should not be used with monoamine oxidase inhibitors (MAOIs) due to serious drug interactions 7
Important Clinical Caveats
- Dextromethorphan should not be used for productive cough where clearance of secretions is beneficial 2, 8
- Simple home remedies like honey and lemon may be as effective as dextromethorphan for benign viral cough and should be considered first-line 2, 3
- Abuse potential exists, particularly among adolescents and young adults engaging in "Robotripping" to achieve psychoactive effects at supratherapeutic doses 6
- In older adults, the combination of dextromethorphan with quinidine requires caution due to increased fall risk and drug interactions 8