Rescue Dose of Dexamethasone
For breakthrough nausea and vomiting despite prophylaxis, administer 12 mg of dexamethasone orally or intravenously daily as rescue therapy. 1
Context and Dosing Framework
The rescue dose differs significantly from prophylactic dosing and depends on the clinical indication:
Chemotherapy-Induced Nausea/Vomiting (CINV)
- Breakthrough CINV: 12 mg oral or IV dexamethasone daily when prophylaxis fails 1
- This is higher than standard prophylactic doses (8 mg for moderate risk, 12 mg for high risk on day 1) 1
- When rescue therapy is needed, use a different class of antiemetic than what was given for prophylaxis 2
Postoperative Nausea/Vomiting (PONV)
- Rescue PONV: Administer a different class of antiemetic than the one used for prophylaxis 2
- If dexamethasone was not used prophylactically, 8 mg is the typical rescue dose based on the DREAMS trial 2
- The 4-5 mg dose has similar clinical effects to 8-10 mg for PONV, though 8 mg showed efficacy in reducing rescue antiemetic needs for up to 72 hours 2
Acute Severe Asthma
- Adults: 10 mg IV as initial dose in severe exacerbations 2
- Pediatric rescue: Single dose of 0.3 mg/kg orally (maximum practical dose ~12 mg) has been studied as an alternative to multi-day prednisolone 3, 4
Other Critical Situations
- Cerebral edema: 10 mg IV initially, followed by 4 mg every 6 hours intramuscularly 5
- Shock/life-threatening situations: Doses may be in multiples of usual dosing, ranging from 20-40 mg IV initially 5
Administration Considerations
Route equivalency: Oral and IV dexamethasone are bioequivalent with 1:1 conversion, allowing flexible administration 1, 5
IV administration technique:
- Administer slowly over several minutes to avoid perineal burning 6
- If burning occurs, slow or pause the infusion temporarily 6
Important Caveats
Dose adjustment with aprepitant: When NK1 antagonists are used concurrently, dexamethasone doses should be reduced due to drug interactions that increase dexamethasone exposure approximately twofold 2
Monitoring requirements: Watch for hyperglycemia (especially in diabetics), GI symptoms requiring PPI prophylaxis, and sleep disturbances 6
Infection prophylaxis: Consider antifungal prophylaxis if steroids are required beyond 48-72 hours 6
Tapering: Never abruptly discontinue after more than a few days of treatment; taper gradually to prevent adrenal insufficiency 6