Lohse, who missed more than a month earlier this year because of an injury to his forearm, struggled with his command on Saturday when he gave up seven hits and four runs in just 3 1/3 innings in his first start since Aug. 21.
He didn't feel 100 percent on Sunday, and the team decided to take an MRI on Monday just to make sure everything was OK.
"The doctors didn't see any reason to slow me down," Lohse said. "It was good to know that nothing was wrong. It was in the back of my head. I didn't know what was going on, and it's good to know that nothing is torn again or overly swollen or anything like that."
Lohse, who has battled a series of nagging injuries for much of the season, had trouble commanding his pitches on Saturday and said that was because of the muscles in his forearm. He is 5-8 with a 4.83 ERA in the first season of a four-year, $41 million contract he signed last September.
"Basically it just boils down to retraining the muscles in there to fire when I want them to," Lohse said after the Cardinals' 11-6 win over Florida on Monday night. "I don't see any problems with going out there. I haven't talked to Tony [La Russa], but I'm sure they will go along with it. I just have to retrain the muscles. They are a little bit off.
"Talking to the doctor, he didn't see any reason [why I shouldn't pitch]. He said I can't hurt it anymore. It's just a matter of getting it to do what it's supposed to do. It was good to know. I was really worried there that something might be wrong, because I don't know what normal soreness is compared to abnormal now at this point. It was a good thing to find out. Now that we know we can't hurt it, we have to just keep working on it."
The Cardinals also received good news regarding John Smoltz on Monday as he nears a return to the Redbirds' rotation.
He originally planned on starting Sunday night, and that still could happen if Lohse is able to start on Friday. If the Cardinals decide to give Lohse a few extra days, then Smoltz could start on either Friday or Saturday, with Chris Carpenter starting on the other day.
Carpenter's regular fifth day would be on Friday, but St. Louis could give him an extra day of rest and have Smoltz start Friday. Adam Wainwright, who will start on Tuesday against Florida, could then start on Sunday on regular rest.
The day Smoltz starts will likely be decided by Lohse's health, and the 42-year-old righty said that the day didn't matter to him.
"To beat a dead horse, I could have pitched today," Smoltz said Monday. "I'm not saying it would have been the most profitable situation, but I could have pitched today. So we're just not taking any chances and we will go from there, but yeah, it's progressed the way I thought two days ago I told you that it would progress."
Smoltz is 1-1 with a 3.27 ERA in four starts since joining the Cardinals.
B.J. Rains is an associate reporter for MLB.com This story was not subject to the approval of Major League Baseball or its clubs.