PRN Dosing of Geritussin (Dextromethorphan)
The recommended PRN (as needed) dosing of Geritussin (dextromethorphan) is 10-20 mg every 4 hours or 30 mg every 6-8 hours as needed for cough, not to exceed 120 mg in 24 hours.
Dosing Guidelines
Adult Dosing
- Standard PRN dosing: 10-20 mg every 4 hours
- Alternative dosing: 30 mg every 6-8 hours
- Maximum daily dose: 120 mg in 24 hours
Pediatric Dosing
- Children 12 years and older: Same as adult dosing
- Children 6-12 years: 5-10 mg every 4 hours or 15 mg every 6-8 hours (maximum 60 mg/day)
- Children 2-6 years: 2.5-5 mg every 4 hours or 7.5 mg every 6-8 hours (maximum 30 mg/day)
- Not recommended for children under 2 years
Clinical Considerations
Efficacy
- Dextromethorphan is a widely used non-opioid antitussive for treatment of cough associated with upper respiratory tract infections
- However, clinical evidence supporting its efficacy is limited, with studies showing minimal difference between dextromethorphan and placebo for cough suppression 1
Safety Profile
- Generally well-tolerated with infrequent and usually mild adverse effects
- Most common side effects are dose-related and include neurological, cardiovascular, and gastrointestinal disturbances 2
- Safety profile is reassuring, particularly regarding overdose in adults and children 2
Important Precautions
Drug Interactions
- Avoid concomitant use with MAO inhibitors as this combination can lead to serious adverse reactions
- Use caution when combining with other CNS depressants
Abuse Potential
- Recreational abuse has become increasingly common in adolescents and young adults 3
- At high doses (typically >300 mg), dextromethorphan can produce dissociative effects similar to ketamine or PCP due to NMDA receptor antagonism 4, 3
- Monitor for signs of abuse, particularly in younger patients
Special Populations
- Use with caution in elderly patients
- Not recommended during pregnancy unless benefits clearly outweigh risks
- Avoid in patients with severe liver disease
Administration Tips
- Take with food if gastrointestinal upset occurs
- Maintain adequate hydration while using
- Discontinue if no improvement after 7 days or if fever, rash, or persistent headache develops
- Consider alternative treatments if cough persists beyond 1-2 weeks
Remember that dextromethorphan is intended for short-term symptomatic relief of cough and should not be used for chronic cough conditions, which require evaluation of underlying causes.