Does Prednisone Raise Blood Pressure? What It Does to Blood Sugar, Too, and When to Call

Yes, prednisone can raise both blood pressure and blood sugar. These are two important side effects to understand before starting treatment, particularly if you already have hypertension, diabetes, or prediabetes.

For many people taking a short five-day course, these changes are temporary. But the effect varies. Some people notice very little difference, while others experience significant blood sugar elevations or fluid retention that affects blood pressure.

The dose, duration, underlying condition, and your medical history all matter. A 20mg prednisone prescription does not automatically cause a specific increase in blood pressure or glucose.

Here's how prednisone affects both, when to monitor your readings, and which symptoms mean you should contact a clinician.

TL;DR: Key Takeaways

• Prednisone can raise blood pressure through fluid retention and other effects on the cardiovascular system.
• It can raise blood sugar by increasing glucose production and making the body less responsive to insulin.
• Blood sugar may rise more noticeably in the afternoon or evening after a morning dose.
• People with diabetes or prediabetes may need more frequent glucose monitoring.
• If you have hypertension, compare readings with your usual baseline and follow your clinician's monitoring advice.
• Do not independently increase blood pressure medication, insulin, or other diabetes medication.
• Blood pressure and glucose often improve after prednisone is stopped, but the timeline varies.
• Severe headache, chest pain, confusion, vomiting, or difficulty breathing require urgent assessment.

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How Prednisone Raises Blood Pressure

Prednisone is a corticosteroid that reduces inflammation. It can also affect how your body handles sodium, water, and blood vessel function.

These effects may cause blood pressure to rise, particularly in people who already have hypertension or cardiovascular or kidney disease.

1. Sodium and fluid retention

Prednisone can contribute to sodium and fluid retention in some patients.

When your body retains more fluid, blood volume may increase. That can put additional pressure on blood vessel walls.

You might notice:

• Swelling in your ankles or feet
• Puffiness
• A temporary increase in weight
• Blood pressure readings above your usual range

Not everyone experiences noticeable fluid retention, and a short course does not guarantee weight gain.

2. Changes in blood vessel function

Corticosteroids can also affect how blood vessels respond to signals that regulate their diameter and tone.

This may contribute to increased vascular resistance and higher blood pressure.

How much can prednisone raise blood pressure?

There is no reliable universal number for a five-day course of prednisone 20mg.

The change depends on your baseline blood pressure, dose, duration, kidney function, other medications, and individual response.

A person whose blood pressure is normally well controlled may notice a small increase. Someone with existing hypertension or heart or kidney disease may need closer monitoring.

Who is more likely to notice a change?

Pay particular attention if you have:

• Pre-existing hypertension
• Kidney disease
• Heart failure or other cardiovascular disease
• A history of fluid retention
• Older age
• Several medications that affect blood pressure

If you take blood pressure medication, continue it as prescribed unless your clinician tells you otherwise.

How Prednisone Raises Blood Sugar

Prednisone can raise blood glucose even in people who have never been diagnosed with diabetes.

It affects how your body produces and uses glucose, which can make blood sugar harder to control during treatment.

What happens inside the body?

Prednisone can:

• Increase glucose production in the liver
• Make muscle and other tissues less responsive to insulin
• Reduce glucose uptake by cells
• Increase insulin resistance

Your body may need more insulin than usual to keep blood sugar within its normal range.

In some people, this causes temporary steroid-induced hyperglycemia. In others, particularly those with existing risk factors, it may reveal previously unrecognized diabetes.

How much can blood sugar rise?

The increase varies considerably. A fixed estimate such as 20 to 50 mg/dL for everyone taking 20mg prednisone is not reliable.

People with diabetes may experience larger increases, and some may need a temporary change to their treatment plan.

People with prediabetes may also be more susceptible.

Why can afternoon blood sugar be higher?

When prednisone is taken in the morning, its glucose-raising effects often become more noticeable several hours later.

A common pattern is:

• Morning: Fasting glucose may look relatively normal.
• After lunch: Blood sugar may begin rising.
• Afternoon or evening: Glucose may reach its highest point.
• Overnight: Levels may move closer to baseline, depending on the dose and individual response.

This is why checking only fasting glucose can miss steroid-related elevations. <Cite refs={["turn156747search1","turn156747search8"]}/>

For guidance on understanding your lab results overall, see our guide on how to read your lab results without panicking.

How to Monitor Blood Pressure During a Five-Day Prednisone Course

If you have normal blood pressure and no relevant medical history, routine twice-daily monitoring may not be necessary for every short course.

If you have hypertension, cardiovascular disease, kidney disease, or a history of significant blood pressure changes with steroids, ask your clinician how often to check.

A practical monitoring approach

1. Check your blood pressure using a properly sized cuff.
2. Sit quietly for about five minutes before measuring.
3. Keep your arm supported at heart level.
4. Take two readings about one minute apart.
5. Record the readings and the time you took prednisone.
6. Compare the results with your usual blood pressure.

If your readings are consistently higher than your baseline, contact your clinician for guidance.

Do not change your blood pressure medication dose on your own.

How to Monitor Blood Sugar During Prednisone Treatment

Monitoring depends on whether you have diabetes, prediabetes, or other risk factors.

If you do not have diabetes

Routine home glucose testing is not usually necessary for every otherwise healthy person taking a brief prednisone course.

However, contact a clinician if you develop symptoms such as:

• Excessive thirst
• Frequent urination
• Unusual fatigue
• Blurred vision
• Unexplained weakness

If you have prediabetes, a family history of diabetes, or previous steroid-related glucose elevations, ask whether temporary monitoring would be useful.

If you have diabetes

Prednisone can make glucose control more difficult, even if your diabetes was previously stable.

Your clinician may recommend checking more frequently, particularly:

• Before meals
• Before dinner
• At bedtime
• At other times specified in your diabetes plan

The afternoon and evening may be particularly useful monitoring periods after a morning prednisone dose.

Keep a log of your readings and medication doses. If your glucose remains above your individualized target, contact your diabetes care team.

Some patients need temporary medication adjustments, but insulin or other diabetes medication should not be changed without an established plan or clinician guidance. <Cite refs={["turn156747search0","turn156747search11"]}/>

What to Do if Blood Pressure or Blood Sugar Rises

The right response depends on the reading, your usual baseline, symptoms, and medical history.

If blood pressure rises

Mild increase without symptoms

• Repeat the reading after resting.
• Record the result.
• Continue prescribed medication.
• Contact your clinician if the increase persists.

Repeated readings around 160/100 or higher

Contact your clinician promptly, particularly if this is substantially above your normal range or you have cardiovascular or kidney disease.

Blood pressure above 180 systolic and/or 120 diastolic

Rest briefly and repeat the measurement.

If it remains this high, seek urgent medical advice. If you also have chest pain, shortness of breath, severe headache, weakness, confusion, or vision changes, call emergency services immediately.

A blood pressure reading alone does not determine whether a hypertensive emergency is occurring. Symptoms and evidence of organ injury matter.

If blood sugar rises

Higher than your usual range but you feel well

• Follow your diabetes monitoring plan.
• Drink water unless you have been given fluid restrictions.
• Avoid sugary drinks.
• Contact your clinician if readings remain elevated.

Repeated readings above 200 mg/dL

Contact your clinician if glucose stays above this level, particularly if you have diabetes or symptoms of hyperglycemia. Your personal target may be different.

Very high readings or symptoms of a diabetic emergency

Seek urgent medical assessment for persistently very high glucose, especially with excessive thirst, frequent urination, vomiting, abdominal pain, or dehydration.

Call emergency services if you have confusion, severe weakness, difficulty breathing, or cannot keep fluids down.

For more on medication interactions during prednisone treatment, see can I take ibuprofen with prednisone, and is Tylenol the safer choice?.

When to Call a Clinician

Seek emergency care now if you have:

• Chest pain or pressure
• Difficulty breathing
• Severe headache with markedly elevated blood pressure
• New confusion or difficulty staying awake
• Sudden vision changes
• Fainting or severe weakness
• Repeated vomiting with signs of dehydration
• Very high blood sugar with symptoms suggesting diabetic ketoacidosis

Do not wait for a routine appointment if these symptoms occur.

Contact your clinician promptly if you:

• Have repeated blood pressure readings substantially above your usual range.
• Have persistent glucose readings above your personal target.
• Develop excessive thirst or frequent urination.
• Notice new swelling or rapid weight changes.
• Have diabetes and are unsure how to manage your medication during prednisone treatment.
• Have hypertension and are concerned about whether your current treatment is adequate.

If you have both diabetes and hypertension, coordinate with the clinicians managing those conditions rather than making medication changes independently.

For prescription and health record management, see our guide on how to view your medical records online for free.

Special Considerations

If you already have hypertension

Before starting prednisone, tell your prescriber if your blood pressure is difficult to control or if you have a history of steroid-related increases.

During treatment:

• Continue your usual blood pressure medication.
• Check readings according to your clinician's advice.
• Keep a record of any swelling or unusual symptoms.
• Report persistent elevations.

A temporary medication adjustment may sometimes be appropriate, but it should be based on your readings and medical history.

If you have diabetes

Prednisone can increase glucose enough to require a temporary change in diabetes treatment.

Before starting, ask your diabetes care team:

• How often should I check my glucose?
• What readings should prompt a call?
• Should I follow a correction-dose plan?
• What should I do when prednisone ends?

As steroid doses decrease or treatment stops, glucose-lowering medication needs may also change. This is particularly important for people using insulin because their risk of low blood sugar can increase as the steroid effect wears off.

If you have both diabetes and hypertension

You may need a more coordinated monitoring plan.

Prednisone can affect both conditions at the same time, so your clinician may want to review your blood pressure readings, glucose log, kidney function, and medication list.

Do not assume that a medication adjustment made for one condition is automatically appropriate for the other.

If you have cardiovascular disease

People with heart failure, kidney disease, or a history of fluid retention may be more vulnerable to complications from sodium and fluid retention.

Report new swelling, rapid weight gain, or worsening shortness of breath promptly.

For more on prednisone timing and administration, see how to take prednisone 20mg for 5 days: dose, timing, and whether you need to taper.

Conclusion

Prednisone can raise both blood pressure and blood sugar, even during a short five-day course. The degree of change varies, so fixed estimates such as a 5 to 15 mmHg blood pressure increase or a 20 to 50 mg/dL glucose rise should not be treated as predictable outcomes for everyone.

If you have diabetes, prediabetes, hypertension, kidney disease, or cardiovascular disease, ask your clinician what to monitor before starting treatment. People with diabetes may need more frequent glucose checks, particularly later in the day after a morning dose.

Continue your prescribed medications unless your clinician changes the plan. Do not independently increase insulin or blood pressure medication.

Seek urgent care for severe symptoms, very high readings, or signs of a diabetic emergency. If blood pressure or glucose remains above your usual range after prednisone ends, arrange follow-up rather than assuming the effects will disappear automatically.