What Is a Comorbidity, Exactly?

By Leah Campbell
Reviewed by Daniel Lew, M.D.
February 27, 2023

According to research, 45 percent of the U.S. population—133 million people—live with at least one chronic condition. These include heart disease, diabetes, psoriasis, asthma, arthritis, cancer, and any other disease that can be long-lasting and often debilitating. Living with and managing any one of these conditions can take a toll, and having two or more usually presents additional challenges. Researchers say that far too many patients with chronic illnesses have comorbidities.

What Is a Comorbidity?

People have comorbidities when they have at least two health conditions at the same time, according to Michael Billet, M.D., an emergency medicine physician at Mercy Medical Center in Baltimore, Maryland.

“The conditions can be completely distinct, but usually they interact with each other, which can make them both more difficult to manage,” says Billet. “They tend to be chronic conditions that a patient lives with and manages long-term.”