From the Guidelines
For most adults with a cough, dextromethorphan is generally the most effective over-the-counter cough suppressant, as it has been shown to suppress acute cough in a single meta-analysis 1. The typical adult dose is 60 mg, as this is the dose at which maximum cough reflex suppression occurs, and it can be prolonged 1. It is essential to be cautious when recommending dextromethorphan at higher doses, as some combined preparations contain other ingredients such as paracetamol 1. Some key points to consider when choosing an over-the-counter cough medication include:
- Dextromethorphan works by suppressing the cough center in the brain
- It is crucial to match the medication to your specific cough type - suppressants for dry, hacking coughs and expectorants for productive coughs with phlegm
- If your cough persists beyond 7 days, is severe, or is accompanied by fever, seek medical attention
- Care must be taken in recommending dextromethorphan at higher doses since some combined preparations contain other ingredients such as paracetamol 1
From the Research
Efficacy of OTC Cough Medications
- The efficacy of over-the-counter (OTC) cough medications has been studied in various clinical trials 2, 3, 4.
- A study published in 1993 found that codeine, dextromethorphan, and guaifenesin are equally effective in relieving cough symptoms 2.
- Another study published in 2018 reported improved lung function and quality of life in a patient with chronic obstructive pulmonary disease (COPD) following treatment with guaifenesin/dextromethorphan 3.
- A 2009 study found that guaifenesin inhibited cough-reflex sensitivity in acute viral cough, and the combination of benzonatate and guaifenesin suppressed capsaicin-induced cough to a greater degree than either agent alone 4.
Comparison of Active Ingredients
- Dextromethorphan is a safe and effective antitussive agent present in several OTC cough and cold medications 5.
- Guaifenesin is an expectorant that helps thin and loosen mucus, making it easier to cough up 2, 3, 4.
- The combination of guaifenesin and dextromethorphan may be an effective therapy for acute cough due to the common cold (URI) 4.
Analytical Methods
- A high-performance liquid chromatography (HPLC) method has been developed and validated for the simultaneous determination of pseudoephedrine, pheniramine, guaifenesin, pyrilamine, chlorpheniramine, and dextromethorphan in cough and cold medicines 6.
- The HPLC method is simple, rapid, and sensitive, with a linear concentration-response relationship and good precision and accuracy 6.