Question: Can COVID cause syncope?

Answered by internal medicine doctor Andrew Vasey, MD

Syncope is the medical term for fainting or passing out. Generally, this condition arises when you have a sudden, temporary decrease in blood flow to your brain. Many syncopal occurrences are benign and result from a short-term cause. Syncope can happen because of the following:

• A decrease in heart rate
• A rapid drop in blood pressure
• Shifts in the amount of blood in specific areas of your body

There are a few reports of people presenting post-COVID who experience syncopal issues. Still, the difficult part for health care providers is that various processes can cause syncope, even without post-COVID complications. Similarly, defining a post-COVID symptom versus a symptom from another pre-existing cause is challenging.

Patients with post-COVID issues can have symptoms related to most organ systems. For example, many post-COVID symptoms are believed to be related to autonomic nervous system dysfunction. With autonomic dysfunction, a person can have inappropriate changes in their heart rate – such as increasing more than it should – with movement or position changes and can feel like they are going to pass out or do pass out. Many medical conditions can cause autonomic dysfunction, not just post-COVID issues.

Given all these factors, the short answer is, it is difficult to determine if syncope is definitively a symptom of COVID-19.