How does Delsym (dextromethorphan) compare to other cough suppressants?

Dextromethorphan (Delsym) vs. Other Cough Suppressants

Dextromethorphan (Delsym) is the recommended first-line treatment for dry cough with superior efficacy and safety profile compared to other cough suppressants like codeine or pholcodine, which have greater adverse effects despite similar efficacy. 1

Efficacy Comparison

Dextromethorphan (Delsym)

• Acts centrally to suppress the cough reflex 1
• Recommended dosage: 30 mg every 6-8 hours, not exceeding 120 mg in 24 hours 1
• Available in extended-release formulation (Delsym) providing 12-hour cough relief 2
• Shown to reduce cough frequency by 21-25.5% compared to placebo in children 3
• Non-sedating opiate derivative with proven cough suppression in meta-analysis 4
• Maximum cough reflex suppression occurs at 60 mg with prolonged effect 4

Other Cough Suppressants

1. Codeine/Pholcodine

   • No greater efficacy than dextromethorphan 4, 1
   • Much higher adverse side effect profile 4, 1
   • Not recommended due to safety concerns 4, 1

2. Menthol

   • Suppresses cough reflex when inhaled 4
   • Effect is acute and short-lived 4
   • Available as menthol crystals or proprietary capsules 4

3. Sedating Antihistamines

   • First-generation antihistamines suppress cough but cause drowsiness 4
   • May be suitable specifically for nocturnal cough 4
   • Newer non-sedating antihistamines (like bilastine) combined with dextromethorphan show efficacy with less drowsiness 5

Safety Considerations

• Dextromethorphan is generally well-tolerated at recommended doses 3
• Care must be taken with higher doses, especially with combined preparations containing other ingredients like paracetamol 4
• Overdose can be serious, particularly in children - a case report showed life-threatening symptoms with blood concentration exceeding 100 ng/mL 6
• The extended-release polistirex formulation (Delsym) has a duration of action 2-3 times longer than standard formulations 6
• Contains sodium metabisulfite, which may cause allergic-type reactions in sensitive individuals 2

Clinical Application

For dry cough management:

1. First-line: Dextromethorphan 30 mg every 6-8 hours (or extended-release formulation for 12-hour coverage) 4, 1, 2
2. Alternative for nighttime cough: Sedating antihistamines if sleep disruption is a major concern 4
3. Adjunctive therapy: Menthol for short-term relief 4
4. Avoid: Codeine or pholcodine due to poor benefit-risk ratio 4, 1

Special Considerations

• For productive cough, guaifenesin (200-400 mg every 4 hours) is recommended instead of dextromethorphan 1
• Simple home remedies like honey and lemon may be beneficial and cost-effective for mild cases 4, 1
• Voluntary suppression of cough may be sufficient in some cases 4
• Cough lasting more than 8 weeks requires evaluation for underlying causes 1

Common Pitfalls

• Using subtherapeutic doses of dextromethorphan (generally recommended OTC doses may be lower than optimal therapeutic doses) 4
• Failing to recognize that extended-release formulations (Delsym) have different dosing schedules than immediate-release products
• Using opiate-based cough suppressants when dextromethorphan would provide similar efficacy with fewer side effects 4, 1
• Treating productive cough with suppressants rather than expectorants 1