The short answer
Dexamethasone and prednisone are common in cancer care. This page covers infection risk and masked fever, blood sugar, appetite and fluid changes, what long courses add, and why the dose is tapered.
Steroids raise your risk of infection and can also mask the fever that would normally warn you.
Call immediately about sore throat, fever, chills or cough, and about any exposure to chicken pox or measles.
Dexamethasone can raise blood sugar, so people with diabetes should test more often than usual.
Increased appetite and weight gain are listed drug effects, not a failure of willpower.
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The full explanation.
Steroids appear in cancer care more often than almost any other supportive medicine. The two you are most likely to be handed are dexamethasone and prednisone. MedlinePlus describes dexamethasone as "similar to a natural hormone produced by your adrenal glands." It says prednisone works "by changing the way the immune system works." This page covers what steroids do to the body. The sleep and mood effects have their own page.
Why a steroid is in your regimen
Sometimes the steroid is the cancer treatment. NCI lists dexamethasone as one of the drugs used for leukemia and lymphoma. It is also used for multiple myeloma and mycosis fungoides. And it is used for cerebral edema with brain tumors. That means fluid build-up in the brain. It also treats hypercalcemia, or too much calcium in the blood. And it treats thrombocytopenia, a low platelet count.
More often it is there to make chemotherapy tolerable. NCI's antiemesis guidance is the guidance on preventing sickness. It puts dexamethasone in the standard anti-nausea combinations at every risk level. The range runs from a four-drug combination before highly emetogenic chemotherapy, down to a single 8 mg dose for low-risk drugs. Infusion-day dosing is covered under premedications.
Blood sugar, fluid, and salt
Hyperglycemia means high blood sugar. It is a listed adverse reaction on the FDA label for dexamethasone tablets. MedlinePlus is direct: "If you have diabetes, dexamethasone may increase your blood sugar level. If you monitor your blood sugar (glucose) at home, test your blood or urine more frequently than usual."
The label lists more. Fluid retention. Sodium retention. Potassium loss. And hypertension, which means high blood pressure. That is where puffiness in the face, hands, and ankles comes from. Your doctor may tell you to follow "a low-sodium, low-salt, potassium-rich, or high-protein diet."
Appetite and the stomach
Increased appetite and weight gain are both listed adverse reactions. Steroid hunger is a drug effect, not a failure of willpower. See weight gain during treatment. Steroids also irritate the stomach lining. The label lists "peptic ulcer with possible perforation and hemorrhage." MedlinePlus says to take dexamethasone "with food or milk." Black or tarry stool means bleeding, not indigestion.
Infection, and the fever that may not appear
This is the part that matters most. The FDA label states: "Patients who are on corticosteroids are more susceptible to infections than are healthy individuals." It adds that "corticosteroids may also mask some signs of current infection." MedlinePlus says prednisone "may decrease your ability to fight infection and may prevent you from developing symptoms if you get an infection." So a steroid can raise your risk. It can also flatten the fever that would normally warn you.
MedlinePlus tells you to "report any injuries or signs of infection (fever, sore throat, pain during urination, and muscle aches) that occur during treatment." For prednisone, one list carries the instruction to "call your doctor immediately." On that list: "sore throat, fever, chills, cough, or other signs of infection."
It also says to stay away from people who are sick. Wash your hands often. And "call your doctor immediately if you think you may have been around someone who had chicken pox or measles." Those infections "can have a more serious or even fatal course" in adults on corticosteroids. Do not have a vaccination or skin test while taking dexamethasone. The one exception is if your doctor tells you that you may. See also fever and infection concerns.
What longer courses add
Over months, the label adds more. It lists muscle weakness, osteoporosis, and pathologic fracture. It lists aseptic necrosis and impaired wound healing. It lists thin fragile skin, cataracts, and glaucoma. MedlinePlus states that "prednisone may increase the risk that you will develop osteoporosis," which means thinning bones. The American Cancer Society says bone density is measured with a DEXA scan. You may have that scan before, during, and after cancer treatment. ACS names the defenses: calcium, vitamin D, weight-bearing exercise, and bone-protecting drugs. A short burst each chemotherapy cycle is not the same exposure as months of daily prednisone.
Why the dose is tapered instead of stopped
Corticosteroids "can produce reversible hypothalamic-pituitary adrenal (HPA) axis suppression." In plain terms: your own adrenal glands go quiet. The drug is doing their job for them. The label says that after long-term therapy the drug should "be withdrawn gradually rather than abruptly." It adds this: "patients should be warned not to discontinue the use of corticosteroids abruptly or without medical supervision."
Stopping prednisone suddenly can cause "extreme tiredness, weakness, slowed movements, upset stomach, weight loss, changes in skin color, sores in the mouth, and craving for salt." The logic runs the other way too. The label says that "increased dosage of rapidly acting corticosteroids is indicated in patients on corticosteroid therapy subjected to any unusual stress." So tell whoever is treating you that you are on steroids. Do that before surgery. Do it during a serious illness.
When to get help sooner
- Call 911 or go to an emergency department if you vomit blood, pass black or tarry stool, or get sudden severe pain across the stomach. The dexamethasone label lists peptic ulcer with possible perforation and bleeding, and that is not something to sleep on.
- Call your care team the same day if a sore throat, chills, a cough, or pain when passing urine appears, or if you have been near anyone with chicken pox or measles. A steroid can flatten the fever that would normally announce an infection, so do not wait for a temperature to arrive first.
- Call your care team within a day or two if your face, ankles or lower legs puff up, your vision blurs, a cold drags on and on, muscles feel weak, a skin rash spreads, or your home blood sugar readings run high.
If your team has given you a different rule for when to call, follow theirs.
Related pages
Steroid Insomnia, Anxiety, and Mood Changes, Side Effects From Steroids and Premedications, Fever and Infection Concerns During Cancer Treatment, and Bone Health and Fractures After Cancer Treatment.
Sources
- DailyMed, U.S. National Library of Medicine: Dexamethasone Tablets, USP (FDA label). https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=93bb34a7-c8ca-4dab-b2a0-cbe011e1090c&type=display
- MedlinePlus, U.S. National Library of Medicine: Dexamethasone. https://medlineplus.gov/druginfo/meds/a682792.html
- MedlinePlus, U.S. National Library of Medicine: Prednisone. https://medlineplus.gov/druginfo/meds/a601102.html
- National Cancer Institute: Dexamethasone. https://www.cancer.gov/about-cancer/treatment/drugs/dexamethasone
- National Cancer Institute: Nausea and Vomiting Related to Cancer Treatment (PDQ) — Health Professional Version. https://www.cancer.gov/about-cancer/treatment/side-effects/nausea/nausea-hp-pdq
- American Cancer Society: Osteoporosis. https://www.cancer.org/cancer/side-effects/osteoporosis.html
Words to know
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Common questions
Why is there a steroid in my regimen at all?
Sometimes the steroid is the cancer treatment. NCI lists dexamethasone among the drugs used for leukemia and lymphoma, and it is also used for multiple myeloma, mycosis fungoides, cerebral edema with brain tumors, hypercalcemia and thrombocytopenia. More often it is there to make chemotherapy tolerable, and NCI's antiemesis guidance puts dexamethasone in the standard anti-nausea combinations at every risk level.
Can a steroid hide an infection?
Yes, and this is the part that matters most. The FDA label states that patients on corticosteroids are more susceptible to infections than healthy individuals, and that corticosteroids may mask some signs of current infection. MedlinePlus says prednisone may decrease your ability to fight infection and may prevent you from developing symptoms if you get one. Report injuries or signs of infection such as fever, sore throat, pain during urination and muscle aches.
Why can I not just stop taking it when I feel better?
Corticosteroids can produce reversible hypothalamic-pituitary adrenal axis suppression, which in plain terms means your own adrenal glands go quiet while the drug does their job. The label says that after long-term therapy the drug should be withdrawn gradually rather than abruptly, and warns patients not to stop without medical supervision. Stopping prednisone suddenly can cause extreme tiredness, weakness, slowed movements, upset stomach, weight loss, changes in skin color, mouth sores and craving for salt.
Will it affect my blood sugar and my weight?
It can. Hyperglycemia is a listed adverse reaction on the FDA label for dexamethasone tablets, and MedlinePlus advises people with diabetes who test at home to check more often than usual. Increased appetite and weight gain are both listed adverse reactions, so steroid hunger is a drug effect rather than a failure of willpower. Fluid retention, sodium retention and potassium loss are what produce the puffiness in the face, hands and ankles.
What does a long course add that a short one does not?
Over months the label adds muscle weakness, osteoporosis and pathologic fracture, aseptic necrosis and impaired wound healing, thin fragile skin, cataracts and glaucoma. MedlinePlus states that prednisone may increase the risk of osteoporosis, meaning thinning bones. The American Cancer Society says bone density is measured with a DEXA scan, and names calcium, vitamin D, weight-bearing exercise and bone-protecting drugs as the defenses. A short burst each chemotherapy cycle is not the same exposure as months of daily prednisone.
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Written by: Cancer ExplainedSources last checked: 2026-08-13 what this meansLast updated: 2026-08-17Next planned review: 2027-01-28
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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