[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/) › Dexamethasone

[Pharmacology](https://durgical.com/en/pharmacology/) · [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)

# Dexamethasone

A potent, long-acting corticosteroid with almost no salt retention, used for severe inflammation, brain oedema and adrenal testing.

Updated 2026-11-01

- Class: [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)
- Receptor: Glucocorticoid receptor (GR), a nuclear receptor
- ATC code: H02AB02
- WHO Model List of Essential Medicines

◎**Glucocorticoid receptor (GR), a nuclear receptor**Dexamethasone

ⓘ The figure shows dexamethasone itself in the ligand-binding domain of the human glucocorticoid receptor, with a coactivator peptide.

**Target in 3D:** Glucocorticoid receptor (GR), a nuclear receptor. PDB structure 1M2Z (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1M2Z) · Drag to rotate · pinch to zoom

## Mechanism of action

Dexamethasone is a fluorinated glucocorticoid that binds the glucocorticoid receptor strongly. The complex enters the nucleus, switches on anti-inflammatory genes and represses NF-κB and AP-1, so cytokines and inflammatory mediators fall. It has practically no mineralocorticoid action and a long biological duration, and it suppresses ACTH, the basis of the dexamethasone suppression test.

- Dexamethasone binds the glucocorticoid receptor in the cytoplasm
- The drug-receptor complex moves into the nucleus
- It switches on anti-inflammatory genes and represses NF-κB and AP-1
- Fewer cytokines, prostaglandins and immune cells reach the tissue

## Pharmacokinetics

**Absorption**
Well absorbed by mouth; injectable, eye and ear forms also exist

**Metabolism**
In the liver by CYP3A4, so inducers and inhibitors change its levels

**Half-life**
Long-acting: its biological effect lasts much longer than hydrocortisone's

## Indications

- Cerebral oedema from brain tumours, craniotomy or head injury
- Dexamethasone suppression test in the study of Cushing syndrome [Cushing syndrome →](https://durgical.com/en/conditions/cushing-syndrome/)
- Severe asthma exacerbations and other allergic states [Asthma →](https://durgical.com/en/conditions/asthma/)
- Rheumatic diseases such as rheumatoid arthritis [Rheumatoid arthritis →](https://durgical.com/en/conditions/rheumatoid-arthritis/)
- Acute exacerbations of multiple sclerosis [Multiple sclerosis →](https://durgical.com/en/conditions/multiple-sclerosis/)
- Palliative care of leukaemias and lymphomas

## Adverse effects

### Common

- Insomnia and restlessness
- Increased appetite and weight gain
- Hyperglycaemia
- Stomach upset
- Acne and easy bruising

### Serious (rare, important)

- Infections, which the drug can also mask
- Adrenal suppression: adrenal insufficiency if stopped abruptly after prolonged use
- Osteoporosis and fractures with long use
- Peptic ulcer and gastrointestinal bleeding, especially with NSAIDs
- Posterior subcapsular cataract and glaucoma
- Psychiatric reactions (euphoria, depression, psychosis)

## Contraindications

- Systemic fungal infections
- Hypersensitivity to the product
- Live or live attenuated vaccines during immunosuppressive doses

## Key interactions

**CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, barbiturates)**
Faster clearance and a weaker corticosteroid effect

**Strong CYP3A4 inhibitors (ketoconazole)**
Higher corticosteroid levels and more side effects

**Aspirin and other NSAIDs**
Higher risk of gastrointestinal ulcer and bleeding

**Potassium-depleting drugs (loop or thiazide diuretics, amphotericin B)**
Hypokalaemia; with digoxin, more risk of arrhythmia

**Warfarin**
The anticoagulant response changes; INR is checked more often

## What is monitored

- Blood glucose
- Blood pressure and weight
- Potassium
- Signs of infection
- Eye pressure and bone density with long use

## Administration and safety

- Comes as tablets, oral solution and injection (sodium phosphate); the routes are not interchangeable without an order
- Oral forms are usually given with food to reduce stomach upset
- After prolonged use the drug is tapered, never stopped suddenly

## Nursing care

- Check glucose, especially in people with diabetes; corticosteroids raise it
- Watch for infection: fever and other signs may be blunted
- Watch mood and sleep; report agitation, depression or confusion
- Teach that a long course is not stopped suddenly; it is tapered under medical supervision
- Ask about black or tarry stools, a sign of digestive bleeding

## Pregnancy and breastfeeding

Used in pregnancy when the benefit justifies it; newborns of mothers on substantial doses are watched for adrenal insufficiency.

## Memory aid

DEXA = Dry and EXtra-strong: no salt retention, long action, suppresses ACTH (the overnight suppression test).

## Test yourself

Think of the answer, then tap the question to see it.

## Why is dexamethasone, and not hydrocortisone, used in the suppression test for Cushing syndrome?

It suppresses ACTH strongly but is not measured by standard cortisol assays, so a fall in measured cortisol reflects the patient's own adrenal output.

## Why is dexamethasone preferred for cerebral oedema around a brain tumour?

It is potent and long-acting with practically no salt and water retention, so it reduces vasogenic oedema without adding fluid load.

## A patient on dexamethasone starts rifampicin. What happens to the steroid effect?

It weakens: rifampicin induces CYP3A4 and speeds dexamethasone clearance.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/dexamethasone/)

## Related drugs

- [Betamethasone](https://durgical.com/en/pharmacology/betamethasone/)
- [Prednisone](https://durgical.com/en/pharmacology/prednisone/)
- [Hydrocortisone](https://durgical.com/en/pharmacology/hydrocortisone/)

## Related conditions

- [Cushing syndrome](https://durgical.com/en/conditions/cushing-syndrome/)
- [Asthma](https://durgical.com/en/conditions/asthma/)
- [Rheumatoid arthritis](https://durgical.com/en/conditions/rheumatoid-arthritis/)
- [Multiple sclerosis](https://durgical.com/en/conditions/multiple-sclerosis/)

[← Back to the class: Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Dexamethasone: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682792.html) (MedlinePlus (U.S. National Library of Medicine), 2017); [DailyMed - DEXAMETHASONE tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=62b1cf42-c53a-40fa-a39c-fa5d90dc065a) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=H02AB02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025).

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Representative model, for educational purposes only.

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