Dexamethasone: Highly Potent and Short-Term — Keeping Blood Sugar, Sleep and Stomach in Check

1. At a Glance: Technical Data Sheet

2. How it works: strong, long-acting, no salt effect

Dexamethasone is a synthetic cortisone (glucocorticoid). It acts like the body’s own stress hormone cortisol, only much more strongly: it enters cells, changes how certain genes are read there and so slows down the production of inflammatory messenger substances and the activity of immune cells. Swelling goes down, and overshooting immune reactions are dampened.^¹

What sets dexamethasone apart from prednisolone, the most commonly prescribed oral cortisone, are three properties — and they determine what it is used for and what it is not. The article on prednisolone describes long-term treatment and tapering in detail. This article is about the typical short, high-dose treatment phases with dexamethasone.

• Very strong: according to the SmPC, dexamethasone is about 7.5 times stronger than prednisolone and 30 times stronger than hydrocortisone.^¹ 4 mg of dexamethasone therefore corresponds to roughly 30 mg of prednisolone. A small tablet is not a small dose.
• Very long-acting: in the blood, half of the dexamethasone is broken down after a few hours, but in the cells its effect lasts for more than 36 hours.^¹ With daily dosing, it can build up.
• No salt effect: unlike hydrocortisone and, to a lesser degree, prednisolone, dexamethasone hardly retains any salt or water. That makes it well suited when swelling needs to go down — in the brain, for example.

3. Dosing: very different depending on the reason

Hardly any other medicine has doses that vary as widely as those of dexamethasone. The following examples reflect the SmPC and are not a dosing instruction. Which dose is given and for how long is set by the treating practice or hospital.^¹

• Nausea during chemotherapy: 10 to 20 mg before the start of chemotherapy, then if needed 4 to 8 mg two to three times a day for a few days — usually combined with other anti-nausea medicines such as ondansetron.
• Swelling of the brain (cerebral oedema), for example with brain tumours: high doses into a vein at first, then 16 to 24 mg a day as tablets, divided into several single doses over a few days; with radiotherapy or inoperable tumours, also for longer and at lower doses.
• Severe asthma attack: 8 to 20 mg in adults, according to body weight in children.
• COVID-19 requiring oxygen: 6 mg once a day for up to 10 days — only in adults and adolescents who need additional oxygen. Without a need for oxygen, the pivotal study showed no benefit.^¹
• Palliative treatment in cancer: 8 to 16 mg at first, 4 to 12 mg a day when given for longer, for example against loss of appetite, weakness or pain caused by swelling.
• Rheumatic and autoimmune diseases, severe skin diseases: higher doses for initial treatment, then a reduction — often with a switch to prednisolone.

Whatever the reason, the SmPC states: the dose and duration of treatment should be as high and as long as necessary, but as low and as short as possible. The dose is always reduced in steps; how quickly depends on the underlying condition and the duration. With an underactive thyroid or liver cirrhosis, lower doses may be enough.^¹

4. Taking it in everyday life

1. In the morning, with or after breakfast. According to the SmPC, the daily dose is taken as a single dose in the morning wherever possible — in line with the body’s natural cortisol rhythm — and swallowed whole with liquid during or after a meal.^¹
2. With several doses: not too late for the last one. At high doses, two to four doses a day are often needed. Many practices schedule the last dose for midday or early afternoon so that sleep suffers less. Ask whether that is possible for you.
3. Two hours apart from antacids. Acid-binding stomach remedies containing aluminium or magnesium hydroxide can reduce absorption; the SmPC recommends a two-hour gap.^¹
4. Write the schedule down. During chemotherapy, the dose often changes from day to day — high on the day of the infusion, for example, then lower. A plan with dates and times prevents tablets from being taken twice or forgotten.
5. Missed dose: what applies depends on your schedule. Do not take a double amount; ask your practice or pharmacy instead — especially with dexamethasone for nausea, where timing matters. General rules in the guide missed a medication.

5. Side effects: short-term and long-term

The side effects of dexamethasone depend heavily on the dose and duration. The SmPC therefore does not give frequencies.^¹ For everyday life, a simple distinction helps: what shows up after just a few days, and what is only a risk with longer use?

Even with short courses

• Raised blood sugar: glucose tolerance falls, existing diabetes gets out of control more easily, and undiagnosed diabetes can come to light.
• Sleep problems, restlessness, mood swings: according to the SmPC, euphoria, increased drive, irritability, anxiety and depression are possible, and rarely also psychoses.
• Increased appetite: food cravings are common and can even be welcome during chemotherapy.
• Stomach problems: from heartburn to ulcers and bleeding, especially together with anti-inflammatory painkillers.
• Hiccups: explicitly mentioned in the SmPC and a well-known, usually harmless side effect of dexamethasone.
• Higher blood pressure and, at high doses, a slow pulse.

With longer use

• Cushing’s syndrome: a moon face, fat deposits around the trunk, thin skin, bruising, stretch marks. According to the SmPC, pronounced side effects are to be expected with longer-term treatment from about 1.5 mg a day.^¹
• Bone loss: osteoporosis is dose-dependent and, according to the SmPC, possible even with short-term use. The German DVO guideline counts glucocorticoid treatment among the important risk factors for osteoporosis and fractures.^¹,² More under medications and osteoporosis risk.
• Muscle weakness, especially in the thighs and shoulders, and delayed wound healing.
• Eyes: cataracts and raised eye pressure up to glaucoma; with long-term treatment, the SmPC provides for eye check-ups every three months.
• Infections: the immune defences are weakened, and signs of infection such as fever can be masked. Chickenpox and measles can take a severe course.
• Adrenal insufficiency: the body’s own cortisol production can remain suppressed for months after stopping.

6. Blood sugar, sleep, stomach: the three trouble spots during a cortisone course

This is the most important section of this article. People who are given dexamethasone usually take it for only a few days — but at doses that pack a punch. Three problems keep coming up, and you can prepare for all three.

Trouble spot 1: blood sugar

Cortisone makes the liver release more sugar into the blood and makes cells less sensitive to insulin. According to the SmPC, this can increase the need for insulin or diabetes tablets.^¹ Typically, blood sugar rises over the course of the day after a morning dose — so a fasting value in the morning can be misleading. Because of its long duration of action, with dexamethasone it can also stay raised overnight.

• If you have diabetes: before starting, agree with your practice how often and when to measure and how your diabetes medicines will be adjusted — especially insulin. Measurements in the afternoon and before the evening meal are often more revealing than the fasting value alone. Tips under measuring blood sugar correctly.
• Without known diabetes: with high doses over several days and risk factors such as excess weight or previous gestational diabetes, a check can make sense. Warning signs are severe thirst, frequent urination and tiredness; see excessive thirst.
• After stopping: blood sugar usually falls again. If your diabetes treatment was increased, it has to be reduced again — otherwise there is a risk of hypos (low blood sugar).

Trouble spot 2: sleep

Cortisone is a stimulant. On dexamethasone nights, many people lie wide awake, feel wired, irritable or keep brooding. Taking it in the morning is the most important adjustment. If several doses are needed, it is worth asking whether the last one can be taken earlier in the day. Short-term sleep problems during a treatment phase are common and usually temporary; tips on sleep hygiene can be found under sleep disorders. Taking a sleeping tablet on your own initiative is not a good idea — it is better to discuss with your treatment team what suits your situation.

Trouble spot 3: the stomach

Dexamethasone on its own irritates the stomach, but the real risk arises in combination: according to the SmPC, with ibuprofen, diclofenac or aspirin the risk of stomach and bowel ulcers and bleeding increases.^¹ With high doses, several risk factors or such a combination, practices therefore often prescribe stomach protection such as pantoprazole. Taking it with food is additionally gentle on the stomach. More in the guide stomach problems from medications.

And stopping?

Short courses of a few days, for example to prevent nausea, are often ended according to a schedule without a long taper — this is decided by the treating practice. After longer use, an abrupt stop risks adrenal insufficiency with weakness, dizziness, nausea and a drop in blood pressure, as well as a flare-up of the underlying condition or a cortisone withdrawal syndrome with muscle and joint pain.^¹ The dose is then reduced step by step, sometimes with a switch to prednisolone. How this works is described in the guide stopping cortisone.