U.S. Sen. Chuck Grassley, R-Iowa, was receiving antibiotic infusions at an area hospital to treat an infection, his office said Tuesday.
"He is in good spirits and will return to work as soon as possible following doctors’ orders," a statement said.
No other details were released.
Grassely, 90, was first elected to the Senate in 1980 and has been reelected seven times.
He is the Senate's oldest member following the death of Sen. Dianne Feinstein, D-Calif., in September.
Feinstein faced criticism over her deteriorating health in her final years and her ability to serve.
Many aging congressional leaders, as well as President Biden, have also faced questions over their fitness to serve in recent years.