What are the recommended treatments and dosages for cough medicine, including dextromethorphan (cough suppressant) and guaifenesin (expectorant)?

Recommended Cough Medicine Treatments

For acute viral cough, start with honey and lemon as first-line therapy, and if pharmacological treatment is needed, use dextromethorphan 30-60 mg (not the standard OTC dose of 10-15 mg which is subtherapeutic) for optimal cough suppression; guaifenesin is ineffective and not recommended. 1

First-Line Approach: Non-Pharmacological

• Simple home remedies like honey and lemon are as effective as pharmacological treatments for benign viral cough and should be tried first 1, 2
• The mechanism appears to be central modulation of the cough reflex through voluntary suppression 1
• Honey acts as a demulcent, coating the irritated pharynx and reducing mechanical triggers 1

Pharmacological Treatment: Dextromethorphan

Optimal Dosing Strategy

• Standard OTC dosing of dextromethorphan (10-15 mg) is subtherapeutic and inadequate 1
• Maximum cough reflex suppression occurs at 60 mg, which can provide prolonged relief 1
• For routine use, 30-60 mg provides optimal suppression with dosing every 4-6 hours as needed 1
• Maximum daily dose should not exceed 120 mg 1

Clinical Evidence

• Dextromethorphan reduces cough frequency by 19-36% in adults with upper respiratory infections at 30 mg doses 1
• It has superior safety compared to codeine, with fewer adverse effects including no risk of physical dependence 1, 3
• In head-to-head comparison, dextromethorphan lowered cough intensity more effectively than codeine and was preferred by patients 3

Important Safety Caveat

• Check combination products carefully - many contain acetaminophen or other ingredients that can reach toxic levels at higher dextromethorphan doses 1
• Use pure dextromethorphan formulations when prescribing 60 mg doses 1

Guaifenesin: Not Recommended

• Guaifenesin is ineffective for cough suppression in patients with bronchitis based on randomized controlled trials 4
• Despite being marketed as an expectorant, evidence shows no benefit for cough clearance 4
• The ACCP guidelines give it a Grade D recommendation (good evidence, no benefit) 4

While one industry-supported review suggests potential utility 5, the higher-quality ACCP evidence-based guidelines from controlled trials demonstrate lack of efficacy 4. Do not prescribe guaifenesin for cough management.

Alternative Options for Specific Situations

For Nocturnal Cough

• First-generation sedating antihistamines (like diphenhydramine or chlorpheniramine) can suppress cough while providing sedation beneficial for sleep 1, 6
• The sedation is actually therapeutic when cough disrupts sleep 1

For Acute Short-Term Relief

• Menthol inhalation provides rapid but brief cough suppression through direct reflex inhibition 1
• Can be prescribed as menthol crystals or proprietary capsules 1

For Chronic Bronchitis

• Ipratropium bromide inhaled is the only recommended anticholinergic for cough in chronic bronchitis (Grade A recommendation) 4
• Codeine may be considered for chronic bronchitis specifically (Grade B), but NOT for upper respiratory infections 4, 7
• Codeine has no greater efficacy than dextromethorphan but significantly more adverse effects including drowsiness, constipation, nausea, and physical dependence 4, 1

For Postinfectious Cough

• Try inhaled ipratropium first before central antitussives 1
• If ipratropium fails, then consider dextromethorphan 1
• For severe paroxysms unresponsive to the above, prednisone 30-40 mg daily for a short course may be indicated 1

Clinical Algorithm

1. Start with honey and lemon for all acute viral cough 1, 2
2. Add dextromethorphan 30-60 mg if additional relief needed (use pure formulation at higher doses) 1
3. For nighttime cough, use sedating antihistamine instead of or in addition to dextromethorphan 1
4. For chronic bronchitis, use ipratropium bromide as first-line pharmacological agent 4
5. Avoid codeine except in chronic bronchitis where other options have failed 4, 7
6. Never use guaifenesin - it is ineffective 4

Common Pitfalls to Avoid

• Prescribing standard 10-15 mg dextromethorphan doses - these are inadequate for meaningful cough suppression 1
• Using combination products at higher dextromethorphan doses - risk of acetaminophen or other ingredient toxicity 1
• Prescribing codeine for URI-related cough - no evidence of benefit and significant adverse effects 4, 7
• Recommending guaifenesin as an expectorant - controlled trials show no efficacy 4
• Continuing antitussive therapy beyond 3 weeks - cough persisting this long requires diagnostic workup, not continued symptomatic treatment 1