Tobias Halland Johannessen, the man eighth on general classification at the Tour de France, required oxygen at the finish of stage 16 after feeling chest pain.
The Uno-X Mobility rider finished 28th on Mont Ventoux on Tuesday, maintaining his top 10 position at this year's race, but was then seen by medical staff.
A statement from Uno-X on Instagram read: "Tobias suffered some right sided upper abdominal pain during the final climb today. He made it to the finish where he was seen immediately by the race doctors and given oxygen.
"He is feeling much better but will go to the local hospital for further checks.
"We will provide an update in due course."
The 25-year-old Norwegian is a former winner of the Tour de l'Avenir but has been one of the GC revelations at this year's race, climbing into the top 10 overall after stage 10 to Le Mont-Dore.
“He feels much better. That was dramatic seeing him lying down with stomach pain, but luckily, he feels better and will go to the hospital for a check-up. That was our team doctor's advice, so I think that's the best thing to do," Uno-X Mobility team manager Thor Hushovd told WielerFlits.
"It's too early to say [how it will affect the coming days]. Now, the most important thing is that Tobias is doing better and well, and the health of the rider is the most important thing for us now. If there are issues, we will listen to that, but we won't know until later today."
Norway's TV2 have stated that he should be at the start tomorrow.
Despite his issues on today's stage, Halland Johannessen remains eighth overall after finishing 28th on today's stage, 17:01 down on Tadej Pogačar. Rather than a gaping time-gap he enjoyed to ninth-placed Carlos Rodríguez (Ineos Grenadiers) yesterday however, he now has nearly man Ben Healy (EF Education-EasyPost) breathing down his neck, less than a minute behind.
Over the past 10 days or so Halland Johannessen has slowly been climbing through the GC ranks, finding his stride in the mountains and taking fourth place on stage 12 to Hautacam, which took him from 10th to eighth place on GC.
