From the Guidelines
For adults with a persistent dry cough, dextromethorphan is the most effective over-the-counter option, typically taken every 4-6 hours at 10-30 mg per dose, not exceeding 120 mg in 24 hours. This recommendation is based on the evidence from 1, which suggests that dextromethorphan is effective in suppressing cough in patients with chronic bronchitis.
Key Points to Consider
- Cough suppressants should only be used for dry, non-productive coughs; productive coughs that bring up mucus serve a useful purpose in clearing the airways and generally shouldn't be suppressed.
- Codeine-based suppressants are more potent but require a prescription due to their potential for dependence.
- If your cough persists beyond 7 days, is accompanied by fever, or produces discolored phlegm, you should consult a healthcare provider as these may indicate a more serious condition requiring different treatment.
Mechanism of Action
Cough suppressants work by acting on the cough center in the brain or by reducing the sensitivity of cough receptors in the throat. The most common centrally acting drugs deemed to be effective in patients with chronic bronchitis include codeine and dextromethorphan, which can suppress cough counts by 40 to 60% 1.
Important Considerations
- The effects of these drugs on cough can vary depending on the underlying condition, with codeine and dextromethorphan being more effective in chronic bronchitis than in cough due to URI.
- The limited activity of these drugs against cough due to URI is not predictable based on our current understanding of the physiology and pharmacology of the cough reflex 1.
From the FDA Drug Label
Purpose Cough suppressant
Package/Label Principal Display Panel Compare to Delsym® active ingredient Dextromethorphan Polistirex Extended-Release Oral Suspension Cough Suppressant
- Dextromethorphan is used as a cough suppressant 2 2.
- The primary purpose of dextromethorphan is to provide cough relief.
From the Research
Cough Supressant Types
- Centrally acting opioids: morphine, codeine, and dextromethorphan 3
- Peripherally acting antitussives: moguisteine and levodropropizine 3
- Other centrally acting drugs: amitryptiline, paroxetine, gabapentin, and carbamezepine 3
Efficacy of Cough Supressants
- Dextromethorphan and codeine were found to be similarly effective in reducing cough frequency in patients with chronic cough 4
- Dextromethorphan was found to be more effective in reducing cough intensity than codeine 4
- Codeine and dextromethorphan were not found to be more effective than placebo in treating night cough in children 5
- Dextromethorphan was found to attenuate capsaicin-induced cough in healthy volunteers 6