The right-hander delivered the message in this tweet a short time ago. Manager Buck Showalter confirmed the news a few minutes later while meeting with reporters.
Guthrie, who won the Orioles' season opener Friday in St. Petersburg, Fla., against the Rays, said he will be rooting for a victory from the hospital. He's still scheduled to make Wednesday's start against the Tigers. Brad Bergesen would take his place if he's scratched.
"He started running a fever yesterday," Showalter said. "We thought we got it under control. Talking to him last night when we got here, he felt pretty good, but somewhere between that and today, his fever spiked back up. He's over there now trying to get a grip on what we're dealing with.
"I'm not sure if he'll be here or not. I expect him to probably come in and give us an update on where he is with it, but right now he's still tentatively scheduled to pitch on Wednesday. We'll see what the next couple of days bring. We'll probably make a decision on that tomorrow."
"Mark (Connor) is going to give Bergy a light day today in case we're going to need him on Wednesday."