Dexamethasone

Key facts

• Dexamethasone is a potent, long-acting corticosteroid taken by mouth, injection, eye drops, or other topical forms to reduce severe inflammation, allergic reactions, swelling in the brain, croup, and chemotherapy-related nausea, and to treat severe COVID-19 in people who need oxygen.
• Doses and course length vary widely by condition, from a single dose to months of daily treatment.
• Taken for more than a few weeks, dexamethasone suppresses the body's own cortisol production. Stopping suddenly can cause adrenal crisis (dangerously low blood pressure, vomiting, collapse), so long courses are tapered down gradually and never stopped abruptly.
• Seek urgent care for severe stomach pain, vomiting blood, sudden vision changes, or signs of infection such as a fever with a fast heartbeat.

What dexamethasone treats

Dexamethasone treats severe allergic reactions and inflammation, autoimmune flares, croup, and swelling in the brain from tumors or injury. It is part of chemotherapy regimens to prevent nausea and vomiting, and is given to hospitalized patients with severe COVID-19 who need oxygen or ventilation. Eye and ear drop forms treat local inflammation. It does not treat the infections that sometimes cause inflammation, only the swelling itself, so it is combined with antimicrobial treatment when an infection is present.

How dexamethasone works

Dexamethasone enters cells and switches off genes that produce inflammatory chemicals, while switching on genes that calm the immune response. This lowers swelling, redness and immune activity throughout the body, but the same suppression is why it can hide the usual signs of infection and raise blood sugar.

Before you take it

• Tell your prescriber about diabetes, high blood pressure, peptic ulcers, osteoporosis, glaucoma, or a current or recent infection, including tuberculosis.
• Avoid live vaccines while on a significant dose; dexamethasone suppresses the immune response those vaccines need to work safely.
• NSAIDs, such as ibuprofen, taken alongside dexamethasone raise the risk of stomach ulcers and bleeding.
• Tell your prescriber if you are pregnant. Short courses are sometimes used deliberately in pregnancy, for example to mature a baby's lungs before an early delivery, but this needs specialist input.

Side effects

Common effects include increased appetite and weight gain, indigestion, mood changes, difficulty sleeping, and raised blood sugar.

Stop and seek urgent medical care for any of these:

• Severe stomach pain or vomiting blood.
• Sudden vision changes.
• Signs of infection, such as fever or chills, appearing without an obvious cause.
• Extreme thirst, frequent urination, marked swelling, or confusion.

Safety essentials

• Never stop a course of more than two to three weeks abruptly. Taper the dose as instructed; untapered withdrawal can cause adrenal crisis, a medical emergency.
• Long-term use needs monitoring of blood sugar, blood pressure, bone density and eyes, since dexamethasone raises the risk of diabetes, high blood pressure, osteoporosis and cataracts.
• Because it dampens the immune system, it can mask the usual signs of a serious infection; report any new fever or feeling unwell promptly rather than waiting for it to worsen.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.