Anabolic steroids are sometimes used to build muscle faster, especially by young men and bodybuilders.
But new research suggests these drugs may interfere with the heart’s normal rhythm and could be particularly dangerous for people who already have a genetic risk of heart disease.
The research was carried out by scientists from the University of Birmingham and research teams in Germany. Led by Dr. Laura Sommerfeld from University Medical Center Hamburg-Eppendorf, the study was published in The Journal of Physiology.
Anabolic steroids are laboratory-made drugs that act in ways similar to testosterone, a hormone naturally produced by the body. Doctors use certain forms of these medicines for specific medical conditions, but some people take much larger amounts without medical supervision to increase muscle size and improve physical appearance.
This has become an important health concern as fitness and bodybuilding content has grown on social media. Steroid use can produce visible changes in muscle, but the effects inside the body may be much less obvious.
The researchers focused on a heart condition called arrhythmogenic right ventricular cardiomyopathy, or ARVC. It is an inherited disease that changes the structure of heart muscle and can make the heart more likely to develop abnormal electrical signals.
People with ARVC can develop dangerous changes in heart rhythm, and the condition is seen more often in men. Scientists have suspected that male hormones such as testosterone may help explain some of this difference between men and women.
In the new research, scientists examined how exposure to anabolic steroids affected the heart, particularly when there was already a genetic weakness linked to ARVC. They found that steroid exposure could worsen electrical changes in the upper chambers of the heart, known as the atria.
These chambers normally receive blood returning to the heart and then move it into the lower pumping chambers. Their electrical activity must remain carefully coordinated for the heart to beat normally.
The study found that six weeks of anabolic steroid exposure was enough to cause harmful changes in electrical activity. These changes increased the likelihood of atrial fibrillation, a condition in which the upper chambers of the heart beat rapidly and irregularly.
Atrial fibrillation can cause symptoms such as a racing heartbeat, tiredness, shortness of breath, or dizziness, although some people have no obvious symptoms. Over time, the condition can increase the risk of blood clots, stroke, and other heart problems.
Professor Larissa Fabritz, one of the researchers, explained that high testosterone levels may make inherited heart muscle diseases worse. This suggests that people carrying certain genetic changes could face an especially high risk if they use anabolic steroids.
The findings do not mean that every person who uses anabolic steroids will develop atrial fibrillation. However, they add to existing evidence that non-medical steroid use can affect more than muscles and appearance.
Previous research has linked anabolic steroid misuse with high blood pressure, unhealthy cholesterol levels, changes in heart structure, and a greater risk of serious cardiovascular problems. Because some heart conditions can remain hidden for years, a person may not know they have an inherited risk before using steroids.
The study offers an important warning at a time when muscle-building drugs can be promoted online as a quick route to a stronger body. Increasing muscle size may be the visible effect, but changes to the heart’s electrical system could carry much more serious consequences.
If you care about health, please read studies about the benefits of low-dose lithium supplements, and what we know about egg intake and heart disease.
For more health information, please see recent studies about potatoes and high blood pressure, and results showing 6 best breads for people with heart disease.
Copyright © 2026 Knowridge Science Report. All rights reserved.
