Dexamethasone: what it treats, how to take it, side effects
Last updated September 3, 2026.
Dexamethasone is a corticosteroid - a version of a hormone your adrenal glands make naturally. It is one of the most potent anti-inflammatories in the pharmacy, used for everything from arthritis flares to severe allergies to certain cancers, and its rulebook is simple: never stop it abruptly.
What does it treat?
Replacing the natural hormone when the body does not make enough, and relieving inflammation across a long list: certain forms of arthritis; skin, blood, kidney, eye, thyroid, and intestinal disorders like colitis; severe allergies; asthma; and certain types of cancer.
How do you take it?
Tablet or liquid, on the schedule your doctor writes - dosing varies widely by condition. When you start, ask your doctor what to do about a missed dose and write it down; for once-a-day schedules, take it when you remember unless the next one is close, and never double up. The standing rule: do not stop without your doctor. Stopping abruptly can cause loss of appetite, upset stomach, vomiting, drowsiness, confusion, headache, fever, joint and muscle pain, peeling skin, and weight loss - after long or high-dose use, the exit is a gradual taper, and withdrawal symptoms during the taper mean calling, because you may need to slow down or step back up.
Side effects to know
- Common: upset stomach, vomiting, headache, dizziness, insomnia, restlessness, depression, anxiety, acne, increased hair growth, easy bruising, and irregular or absent periods.
- Serious - call your doctor immediately: skin rash; a swollen face, lower legs, or ankles; vision problems; a cold or infection that lasts a long time; muscle weakness; and black or tarry stools.
Who should not take it?
A fungal infection anywhere but the skin means a doctor conversation first - steroids and fungi do not mix. Flag liver, kidney, intestinal, or heart disease; diabetes; an underactive thyroid; high blood pressure; mental illness; myasthenia gravis; osteoporosis; herpes eye infections; seizures; tuberculosis; and ulcers. Aspirin, NSAIDs like ibuprofen and naproxen, and ephedrine interact - and with an ulcer history or regular aspirin use, alcohol needs limiting because dexamethasone makes the stomach more vulnerable to it. Report every symptom change during treatment, and tell any surgeon or dentist you take it. If you become pregnant, call your doctor.
When is it an emergency?
Black or tarry stools, vision problems, or severe weakness mean immediate care. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What a Pymander AI doctor consult looks like
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Common questions
Why can't I stop dexamethasone suddenly?
Your adrenal glands make this hormone naturally, and the tablets tell them to take a break. Stop abruptly and the body is left short - MedlinePlus lists the result: loss of appetite, vomiting, drowsiness, confusion, headache, fever, joint and muscle pain, peeling skin, weight loss. After long or high-dose use, the exit is a gradual taper your doctor directs, and feeling withdrawal symptoms mid-taper means calling, because the taper may need to slow.
Why did my doctor ask about fungal infections before prescribing it?
Steroids turn down the immune system - that is how they stop inflammation - and a fungal infection anywhere but the skin can bloom when immunity drops. MedlinePlus says not to take dexamethasone with such an infection without talking to your doctor. Same reason a cold that lasts a long time is on the call-immediately list: on steroids, small infections do not always stay small.
Can I drink alcohol while taking dexamethasone?
Limit it, and be honest about your history. MedlinePlus says dexamethasone makes the stomach and intestines more susceptible to the irritating effects of alcohol, aspirin, and arthritis medications - raising ulcer risk, especially with an ulcer history or regular aspirin use. A short course at low dose is a different conversation than months of therapy, so calibrate with your doctor.
Why can't I take ibuprofen with dexamethasone?
Aspirin and NSAIDs - ibuprofen, naproxen - are named interactions: the combination multiplies stomach irritation and ulcer risk, the same pathway as the alcohol warning. If pain or fever shows up during the course, ask your doctor what to use instead. Ephedrine, the decongestant in some cold products, is on the list too.
Why am I wide awake at 2 am on dexamethasone?
Insomnia and restlessness are on the common-effects list - steroids are activating. Taking the dose early in the day blunts it for many people, but ask your prescriber before shifting the schedule. Anxiety and low mood are on the list too, and both are worth reporting rather than enduring, especially on longer courses.
What happens if I miss a dose of dexamethasone?
MedlinePlus's first instruction is unusual: ask your doctor at the start what to do about a missed dose, and write it down - the answer depends on your schedule. For once-a-day dosing, the standard rule applies: take it when you remember unless the next one is close, and never double up.