In the first month since the dungeon opened, 15 people have fainted and another four have vomited, apparently due to fear.
Visitors to the medieval dungeon are greeted by fake blood and life-size models of victims on the rack. Guides demonstrate how prisoners used to have their tongues ripped out.
Sue Kemp, general manager of Warwick Castle, said: "Our first month has certainly proved that the castle dungeon isn't for the fainthearted or those of a delicate constitution."
An official commented: "If there are many more incidents like these then the dungeon will have to be toned down."
Warwick Castle was built by William the Conqueror in 1068 and used as a fortification. Some of the early prisoners were French soldiers.
During the English Civil War in the 1640s it was a parliamentarian headquarters in which senior royalists were held prisoner.
Publicity for the dungeon attraction refers to "decaying bodies, chanting monks, torture implements and execution.