Prednisone is a corticosteroid (steroid drug) used to treat inflammation. It is often prescribed to people with severe allergic reactions, certain forms of arthritis, various immune system disorders, and even certain types of cancer.

Despite its usefulness, prednisone is known to cause side effects, one of which is a change in heart rate.

This article explains how prednisone can affect the rate and rhythm of the heart. It also takes a closer look at who is at particular risk for this and if prednisone needs to be avoided by certain people.

Why Prednisone Is Prescribed

Prednisone works by suppressing the immune system to reduce inflammation. Inflammation is the body’s response to anything it considered harmful, but there are times when too much inflammation can do more harm than good.

Prednisone is used to treat many inflammatory conditions and autoimmune disorders (which occur when the body attacks its own cells and tissues).

Among the conditions for which prednisone may be prescribed are:

  • Addison’s disease (adrenal insufficiency)
  • Asthma
  • Certain cancers, including acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and lymphoma
  • Chronic obstructive pulmonary disease (COPD)
  • Inflammatory forms of arthritis, including rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and gout
  • Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease
  • Lupus
  • Multiple sclerosis
  • Pericarditis
  • Sarcoidosis
  • Severe allergic reactions
  • Scleroderma
  • Sjögren syndrome
  • Tuberculosis

Side Effects Involving Heart Rate

One of the side effects of prednisone is bradycardia, an abnormally slowed heart rate. Prednisone causes this by decreasing the amount of potassium, calcium, magnesium, and phosphate in the blood.

Recap

Prednisone is a steroid drug used to treat inflammation. It works by suppressing the immune system and is commonly used to treat severe allergies, inflammatory conditions, autoimmune diseases, and certain cancers.

All of these minerals play a role in the rhythm and rate of heartbeats. Calcium in particular helps stimulate contractions of the heart, while magnesium relaxes the heart after contractions. The depletion of these minerals can cause the heart rate to slow, in some cases to dangerous levels.

How often heart problems in prednisone users occur is unclear, but some studies have found that people who take corticosteroids like prednisone for a long time have higher rates of heart attack, heart failure, or stroke.

Prednisone can also sometimes cause atrial fibrillation (rapid, erratic heartbeats), atrial flutter (rapid rhythms in the heart’s upper chambers), and ventricular tachycardia (rapid rhythms in the heart’s lower chambers).

These side effects are most commonly seen with prednisone delivered through a vein (IV). Even so, they have been known to occur with the long-term use of prednisone taken by mouth, particularly at higher doses.  

Who Is at Risk?

Although research has shown that bradycardia can affect anyone taking prednisone, some people are at greater risk. This includes people with pre-existing heart disease or kidney disease.

Prednisone can cause slowed heartbeats by decreasing levels of minerals that help regulate heart rhythm. The risk is greatest with IV prednisone, but it can also occur with long-term use of oral prednisone.

In people given IV prednisone, the rate of infusion also plays a role. When the infusion rate is fast (30 minutes or less), the risk of bradycardia and other heart rhythm problems increases.

As many as 82% of people given high doses of prednisone may experience some form of cardiac arrhythmia (abnormal heartbeat). This can range from mild to life-threatening.

Before Taking Prednisone

If your healthcare provider is suggesting prednisone, be sure they are aware of your medical history.

You are at greater risk for heart rate issues if you take prednisone and have heart or kidney disease. However, this side effect can affect anyone.

People who are at risk of bradycardia or other heart rhythm problems should undergo heart monitoring before receiving prednisone. This includes people with:

  • Congestive heart failure
  • Unstable angina
  • Heart valve disease
  • Atrial fibrillation
  • Aortic aneurysm
  • Hypotension (low blood pressure)
  • History of heart attack or stroke

People with these heart conditions may be able to use prednisone, but that’s not always the case. Your doctor will weigh the benefits and risks of treatment and, if needed, explore other drug options.

Bradycardia is a serious concern as it can cause frequent fainting and other complications, including heart failure, cardiac arrest, and sudden death.

Summary

Prednisone is a steroid drug used to treat inflammatory conditions and autoimmune diseases. While effective, the drug can cause bradycardia (slowed heartbeats) and other heart rhythm problems in some people.

When to Call 911

Call 911 or seek emergency care if you are on prednisone and experience sudden changes in your heart rhythm or symptoms of bradycardia, including:

Those at greatest risk are people who have pre-existing heart or kidney disease, as well as those given prednisone into a vein.

Bradycardia is a serious medical concern as it can lead to frequent fainting, heart failure, cardiac arrest, and sudden death.