Former President Bill Clinton has been hospitalized after he had a urological infection that developed into sepsis, an aide said on Thursday. The aide said Mr. Clinton’s sepsis was not considered to be acute.

In a statement on Twitter, a spokesman for Mr. Clinton, 75, said the former president had been admitted on Tuesday evening to UCI Medical Center in Orange, Calif., with what he described as a “non-Covid-related infection.”

“He is on the mend, in good spirits and is incredibly thankful to the doctors, nurses, and staff providing him with excellent care,” the spokesman, Angel Ureña, said.

Mr. Clinton’s doctors, Dr. Alpesh Amin and Dr. Lisa Bardack, said in a statement that the former president had been admitted to the hospital for “close monitoring” and had received IV antibiotics and fluids. They said that after two days of treatment, his white-blood cell count was trending down and he was “responding to antibiotics well.” They added that Mr. Clinton’s medical team in California had been in touch with his doctors in New York, including his cardiologist.

“He remains at the hospital for continuous monitoring,” Drs. Amin and Bardack said. “We hope to have him go home soon.”

Mr. Clinton was in California for an event related to his foundation. He had started planning a more robust travel schedule after Covid-related restrictions were eased.

Sepsis, a life-threatening response to infection, is a common cause of deaths in hospitals. About 1.7 million Americans develop sepsis in a typical year and nearly 270,000 Americans die as a result of sepsis, according to the Centers for Disease Control and Prevention. Sepsis, or the infection that causes it, starts outside of the hospital in nearly 87 percent of cases.

Infections that lead to sepsis most often begin in the lung, urinary tract, skin or gastrointestinal tract, according to the C.D.C. Without quick treatment, it can lead to tissue damage, organ failure and death.

In 2010, Mr. Clinton was taken to a New York hospital after experiencing chest pains, and later underwent a heart procedure. Doctors inserted two stents into his native coronary artery.

In 2004, Mr. Clinton, who has a family history of heart disease, underwent quadruple coronary bypass surgery at a hospital in New York. The open-heart procedure, which took four hours, came three days after tests prompted by chest pains and shortness of breath revealed that he had life-threatening heart disease.

Mr. Clinton also has a history of skin cancers, cysts, allergies and some hearing problems. Medical tests near the end of his presidency in January 2001 showed elevated levels of cholesterol and blood pressure, but nothing outside the kinds of medical problems often associated with aging.

Jesus Jiménez contributed reporting.