Dexamethasone is a potent corticosteroid, and its side effects are both common and wide-ranging. In one study of patients taking the drug, 83% experienced at least one side effect, with insomnia (31%), digestive upset (21%), neuropsychiatric symptoms (18%), and infections (17%) being the most frequent. The specific risks depend heavily on how long you take it and at what dose.
Common Short-Term Side Effects
Even brief courses of dexamethasone can cause noticeable changes. The most widely reported issues include difficulty sleeping, stomach irritation or heartburn, increased appetite, and weight gain. You may also notice a faster or irregular heartbeat, swelling in your hands or feet, or blurred vision. These effects often appear within the first few days of treatment.
Increased appetite and water retention are responsible for the rapid weight gain many people experience. Your body holds onto more sodium and fluid while on dexamethasone, which is why your fingers, ankles, or face may look puffy. Digestive discomfort, sometimes described as a burning feeling in the upper stomach, affects roughly one in five people taking the drug.
Mood, Sleep, and Mental Health Effects
Dexamethasone has a strong effect on the brain, and mood changes are among the most disruptive side effects people experience. These can range from mild irritability and restlessness to euphoria, anxiety, depression, or rapid mood swings. Some people describe feeling “wired” or unable to turn their thoughts off, especially at night.
Insomnia is the single most commonly reported side effect, affecting about 31% of patients in clinical tracking. It tends to be worse when doses are taken later in the day. More serious psychiatric reactions, including confusion, hallucinations, mania, or suicidal thoughts, are estimated to occur in about 5% to 6% of adults. These severe reactions can also occur in children. If you notice dramatic personality changes or disturbing thoughts during treatment, that warrants immediate attention.
Blood Sugar and Metabolic Changes
Dexamethasone reliably raises blood sugar, even in people who have never had diabetes. Among patients with no prior history of blood sugar problems who take steroids for a month or longer, about 32% develop elevated glucose levels. Roughly 19% go on to develop steroid-induced diabetes. Hospital patients on steroids often see glucose readings above 200 mg/dL, well above the normal range of 70 to 140.
This happens because corticosteroids make your cells more resistant to insulin and prompt your liver to release more glucose. If you already have diabetes, expect your numbers to run significantly higher than usual during treatment. The effect is typically most pronounced in the afternoon and evening hours. Blood sugar usually returns to baseline after dexamethasone is stopped, though some people with pre-existing risk factors may see lasting changes.
Bone Loss and Fracture Risk
Prolonged use of dexamethasone weakens bones, and this process starts faster than most people realize. Bone loss begins within the first few months of treatment, and fracture risk increases as early as three to six months after starting the drug. The spine and hip are the most vulnerable sites.
Older adults face the greatest risk, since they often have lower bone density to begin with. Most guidelines recommend a bone density scan for anyone over 40 who is expected to take oral corticosteroids for more than three months. Younger patients on high doses or long courses may also need monitoring. Children and teenagers on long-term dexamethasone can experience slower growth, which is why regular growth checks are important during treatment.
Eye Problems
Corticosteroids, including dexamethasone, can raise the pressure inside your eyes. When treated with steroids for four to six weeks, about 5% of the general population sees a large spike in eye pressure, and another 30% experience a moderate increase. People who already have glaucoma or a family history of it are far more sensitive: over 90% of patients with open-angle glaucoma show significant pressure elevation during steroid use.
Children appear to be especially susceptible. In studies of children receiving dexamethasone eye drops, 59% to 71% developed elevated eye pressure depending on the dosing frequency. Long-term steroid use also increases the risk of cataracts. If you’re taking dexamethasone for more than a few weeks, periodic eye exams can catch pressure changes before they cause permanent damage.
Immune Suppression and Infection Risk
Dexamethasone suppresses the immune system, which is often the reason it’s prescribed in the first place. But this same effect leaves you more vulnerable to infections. In clinical data, infections were reported in about 17% of patients. These can range from minor issues like oral thrush or skin infections to more serious complications like pneumonia.
Steroids can also mask the usual signs of infection. You might not develop the fever, redness, or swelling you’d normally expect, making it harder to recognize that something is wrong. This is especially relevant if you’re also taking other immune-suppressing medications.
Stopping Dexamethasone Safely
One of the less obvious risks of dexamethasone isn’t a side effect of taking it. It’s what happens when you stop. Your adrenal glands normally produce cortisol on their own, but when you take a synthetic steroid like dexamethasone, they scale back production. If you stop the drug abruptly after your body has adapted, your adrenal glands may not be able to pick up the slack immediately.
This risk becomes meaningful after about three to four weeks of use at doses above 0.25 to 0.5 mg daily. Symptoms of adrenal insufficiency include severe fatigue, weakness, dizziness, nausea, joint pain, and in serious cases, dangerously low blood pressure. Even during a gradual taper, some people experience withdrawal symptoms like body aches, mood changes, and fatigue as the dose decreases. If withdrawal symptoms become severe, temporarily stepping back up to the last tolerated dose and slowing the taper is a standard approach.
Anyone who shows signs of Cushing syndrome during treatment, such as a rounded face, fat deposits between the shoulders, or purple stretch marks, is assumed to have some degree of adrenal suppression and will need a careful, supervised taper rather than an abrupt stop.