Dupuis was a late scratch after feeling symptoms that could have been clot-related and was taken to the hospital.
"He went for precautionary tests before the game, and the tests came back negative,'' Johnston said. "He'll be re-evaluated in Pittsburgh. We want to make sure, so he'll get checked out and won't play tomorrow night [against the Calgary Flames]."
The Penguins did not offer specifics on the symptoms or tests that were conducted.
"That's a medical thing that I don't even want to get into now," Johnston said.
Dupuis was able to return to the arena during the game, and his team welcomed him back after the win.
He did not speak to reporters.
"We've said all along that Pascal's health is the highest priority," general manager Jim Rutherford said earlier Friday. "We will take every precaution necessary to ensure he is in good health."
Dupuis, 36, was limited to 55 games the previous two seasons because of a torn ACL and separate bouts with blood clots. Working his way back from the ACL tear, Dupuis scored six goals in 16 games in 2014-15 before he was forced to sit out the final five months of the season because of the clots.
He missed the first month of this season with a lower-body injury unrelated to the blood clots and debuted Oct. 22. He has one goal in six games.
The Associated Press contributed to this report.