He will be kept overnight for evaluation, and the team announced it would provide updates when available.
"From what I know, it's nothing serious, but obviously whenever you have to go to the hospital, you've got to be worried," Red Sox manager Alex Cora said of his ace, according to Josh Brogadir of WCVB. "But he should be fine. Hopefully, we'll get news in the upcoming hours and he'll join us in Houston."
Sale started Game 1 of the American League Championship Series against the Houston Astros on Saturday, allowing two earned runs on one hit and four walks while striking out five over four innings of work. He was credited with a no-decision in the 7-2 loss.
The 29-year-old is currently scheduled to pitch Game 5 - if necessary - Thursday in Houston.