Dexamethasone Dosing for Bacterial Meningitis in Adults
The typical adult dose of dexamethasone for bacterial meningitis is 10 mg IV every 6 hours for 4 days, started either shortly before or simultaneously with the first dose of antibiotics. 1
Dosing Regimen
- Dose: 10 mg IV every 6 hours 1
- Duration: 4 days total 1
- Total daily dose: 40 mg/day divided into four doses 1
Critical Timing Considerations
Dexamethasone must be initiated before or with the first antibiotic dose to maximize benefit. 1, 2 The drug works by preventing the inflammatory response that results from bacteriolysis when antibiotics kill bacteria in the CSF. 1
If Antibiotics Already Started:
- Can still initiate dexamethasone up to 12 hours after the first antibiotic dose according to UK guidelines 1
- European guidelines are more conservative, recommending initiation within 4 hours of antibiotic start 1
- The UK guideline provides the more permissive 12-hour window based on expert consensus, though earlier is always better 1
When to Continue vs. Stop Dexamethasone
Continue for full 4 days if:
- Pneumococcal meningitis is confirmed or highly probable based on CSF parameters 1
- Haemophilus influenzae meningitis is confirmed 1
Stop dexamethasone if:
- Bacterial meningitis is ruled out entirely 1
- Another bacterial cause (not S. pneumoniae or H. influenzae) is confirmed, though some experts continue regardless 1
- Meningococcal meningitis is confirmed (though this remains somewhat controversial) 1
Evidence Supporting This Regimen
The landmark European Dexamethasone Study (2002) demonstrated that this regimen reduced unfavorable outcomes from 25% to 15% in adults with bacterial meningitis. 3, 2 Specifically for pneumococcal meningitis, unfavorable outcomes decreased from 52% to 26% with dexamethasone treatment. 2
The benefit is most pronounced in high-income countries with advanced medical care. 1 A Cochrane meta-analysis showed dexamethasone reduces hearing loss and neurologic sequelae, with particular mortality benefit in pneumococcal meningitis. 1
Important Caveats
- Not recommended for neonatal meningitis due to insufficient evidence 1
- Use with caution in meningococcal sepsis with shock - the benefit is less clear in patients with severe sepsis, though lower doses may be reasonable 3
- Monitor for gastrointestinal bleeding, though the European study found no increased risk (2 cases in dexamethasone group vs. 5 in placebo) 2
- The 10 mg every 6 hours regimen is specific to adults; pediatric dosing is 0.15 mg/kg every 6 hours 1, 4