Dexamethasone – Uses, Effects & Side Effects

What is Dexamethasone?

Dexamethasone is a synthetic glucocorticoid (corticosteroid) that closely resembles the naturally occurring hormone cortisol. It is one of the most potent and widely used anti-inflammatory drugs in modern medicine. Dexamethasone is included on the World Health Organization (WHO) Model List of Essential Medicines, reflecting its global medical importance.

Mechanism of Action

Dexamethasone works by binding to intracellular glucocorticoid receptors. The resulting receptor-drug complex enters the cell nucleus and modulates gene expression, producing several pharmacological effects:

• Anti-inflammatory action: Inhibition of inflammatory mediators such as prostaglandins, leukotrienes, and cytokines (e.g., interleukin-1, TNF-alpha).
• Immunosuppression: Suppression of T-lymphocyte activity and other immune cells.
• Antiallergic effect: Inhibition of histamine and other allergic mediator release.
• Edema reduction: Decreased vascular permeability, reducing tissue swelling, particularly in the brain.

Indications and Uses

Dexamethasone is used across many medical specialties. Key indications include:

Inflammatory and Allergic Conditions

• Severe allergic reactions and anaphylactic shock
• Acute asthma attacks
• Rheumatoid arthritis and other autoimmune diseases
• Inflammatory bowel diseases (e.g., Crohn's disease, ulcerative colitis)

Neurological Conditions

• Cerebral edema (e.g., related to brain tumors or neurosurgery)
• Bacterial meningitis, to reduce inflammatory complications

Oncology

• Supportive therapy during chemotherapy to reduce nausea and vomiting
• Treatment of certain blood cancers (e.g., multiple myeloma, leukemia, lymphoma)
• Reduction of tumor-related edema

Critical Care and COVID-19

• Treatment of severe COVID-19 requiring oxygen support (as demonstrated by the RECOVERY trial)
• Septic shock with relative adrenal insufficiency

Other Applications

• Prevention and treatment of postoperative nausea and vomiting
• Acceleration of fetal lung maturity in premature birth (antenatal corticosteroid therapy)
• Dexamethasone suppression test for diagnosing Cushing's syndrome

Dosage and Administration

Dexamethasone is available in several forms: tablets, injectable solution (intravenous or intramuscular), eye drops, and ear drops. Dosing varies considerably depending on the indication, ranging from low doses (e.g., 0.5 to 4 mg/day orally) to very high doses (e.g., 10 to 20 mg/day or more in severe conditions). Treatment should always be supervised by a physician. After prolonged use, the dose must be tapered gradually to prevent adrenal insufficiency.

Side Effects

Dexamethasone is a highly effective drug that can cause significant side effects, especially with prolonged or high-dose use:

• Short-term: Sleep disturbances, mood changes (euphoria or depression), elevated blood sugar (especially in diabetic patients), increased appetite, fluid retention
• Long-term: Osteoporosis, muscle weakness, weight gain, Cushing's syndrome (moon face, central obesity), skin thinning (atrophy), increased susceptibility to infections, cataracts, peptic ulcers
• Abrupt discontinuation: Risk of adrenal insufficiency due to suppression of the body's natural cortisol production

Contraindications and Interactions

Dexamethasone should be avoided or used with extreme caution in:

• Active infections (viral, bacterial, or fungal) without concurrent specific treatment
• Peptic ulcer disease
• Severe osteoporosis
• Uncontrolled diabetes mellitus
• Pregnancy (only when clearly indicated)

Important drug interactions exist with non-steroidal anti-inflammatory drugs (NSAIDs, increased risk of gastrointestinal bleeding), anticoagulants (altered clotting), antidiabetic agents (reduced glucose-lowering effect), and live vaccines (risk of vaccine failure or infection).

References

1. World Health Organization (WHO): WHO Model List of Essential Medicines, 23rd Edition, 2023. Available at: https://www.who.int/publications/i/item/WHO-MHP-HPS-EML-2023.02
2. RECOVERY Collaborative Group: Dexamethasone in Hospitalized Patients with Covid-19. New England Journal of Medicine, 384(8):693-704, 2021.
3. Brunton L., Knollmann B. (Eds.): Goodman & Gilman's - The Pharmacological Basis of Therapeutics. 14th Edition. McGraw Hill, 2023.