“Cellulitis, to simply put it, is an infection of the skin,” says Dr. Andrew Petelin, an infectious disease specialist at Mount Sinai Hospital in New York. “The bacteria that cause it enter through cracks or breaks in the skin -- sometimes which are so small that they may not be visible to the eye. More commonly, however, there is a preceding cut or wound that becomes infected, which can then additionally cause infection of the surrounding skin. Usually this happens if the wound is not kept clean or is scratched. If there is a boil, people sometimes think the right thing to do is break it open themselves and squeeze out the pus. By doing this, they are potentially introducing even more bacteria into the wound.”

According to Healthline, common skin injuries like wounds, bites and surgical incision sites cause about 50 to 60 percent of cellulitis cases. And though anyone can get cellulitis, there are some high-risk groups.

“It’s more common with people who have other underlying conditions like diabetes, peripheral vascular disease or those who take immunosuppressive drugs (e.g., transplant patients, those with certain autoimmune conditions, severe skin conditions, or inflammatory bowel diseases),” Petelin says. “Cancer patients who are actively undergoing chemotherapy or HIV patients are at higher risk as well.”

Petelin says people who are obese seem to get cellulitis more often than people who are normal weight. Further, studies show that extreme obesity may affect treatment outcomes in relation to the condition. In fact, obesity may double the rate of adverse reactions.

So just what are the signs of cellulitis? The first two telltale signs are redness and temperature.

“There is a bright red, fiery color to the skin,” Petelin says. “It’s hot and painful when you touch it. In addition, if there is a wound or boil, a pus-like discharge near the area is usually seen.”