Dexamethasone — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Dexamethasone?
Dexamethasone is a potent synthetic glucocorticoid used for a wide range of inflammatory, allergic, oncological, and neurological conditions. This medication is funded by Pharmac for various indications including COVID-19, croup, and cerebral oedema.
What is Dexamethasone Used For?
Dexamethasone is used for cerebral oedema (brain swelling), severe acute allergic reactions and anaphylaxis, COVID-19 in patients requiring supplemental oxygen (as per RECOVERY trial), croup in children, chemotherapy-induced nausea and vomiting, and adrenal insufficiency (as replacement therapy).
How Does Dexamethasone Work?
Dexamethasone is approximately 25 times more potent than cortisol and 7 times more potent than prednisolone. It binds to glucocorticoid receptors and powerfully suppresses the inflammatory and immune cascade. It has minimal mineralocorticoid activity compared to prednisolone.
How to Take Dexamethasone
Dosage varies widely by indication. For COVID-19: 6 mg once daily for up to 10 days. For croup: single dose of 0.15–0.6 mg/kg. For cerebral oedema: 10–20 mg IV initially, then 4–8 mg every 6 hours. For nausea with chemotherapy: 8–20 mg IV. Take oral form with food.
Common Side Effects of Dexamethasone
- Insomnia
- Hyperglycaemia
- Increased appetite and weight gain
- Mood changes (euphoria, irritability)
- Fluid retention
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Adrenal suppression (with prolonged use)
- Avascular necrosis of bone
- Severe infections
- Psychiatric disturbances (psychosis — particularly at high doses)
- Osteoporosis (long-term use)
- Steroid-induced diabetes
Drug Interactions
Dexamethasone may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Same as prednisolone — NSAIDs, rifampicin, carbamazepine, live vaccines, antidiabetic medicines
New Zealand Prescribing Information
Dexamethasone tablets (0.5 mg, 4 mg) and injection (4 mg/mL) are funded by Pharmac. Dexamethasone 6 mg once daily became internationally established for COVID-19 requiring oxygen after the RECOVERY trial demonstrated a significant reduction in 28-day mortality. It is one of the most cost-effective treatments for severe COVID-19.
Frequently Asked Questions
How does dexamethasone help in COVID-19?
The RECOVERY trial showed dexamethasone 6 mg once daily for up to 10 days reduced 28-day mortality by approximately one-third in patients requiring mechanical ventilation, and by one-fifth in those requiring supplemental oxygen. It works by suppressing the harmful “cytokine storm” inflammatory response in severe COVID-19. It is NOT beneficial in patients who do not require oxygen.
Is dexamethasone stronger than prednisone?
Yes — dexamethasone is approximately 7 times more potent than prednisolone. 6 mg dexamethasone is roughly equivalent to 40 mg prednisolone in anti-inflammatory terms. It also has a longer duration of action (36–72 hours).
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: