A WestJet plane was traveling from Cancun to Toronto when it was forced to land at RDU just after 9 p.m.
Four additional ambulances were called in after others on the plane began to feel faint. All of those passengers were examined on the scene, but none of them required hospitalization.
The passenger who was originally sick was taken to an area hospital with a serious medical condition.
The plane was schedule continue its route early Saturday.
RDU provided passengers with food while they waited.