Readers of a book about how to survive the Pamplona bull run may be rethinking their purchase after the American co-author was badly gored by a bull during the stampede.

Bill Hillmann, 32, needed urgent treatment for bloody injuries after a bull caught up with him and skewered him on the point of its horn.

Talk about being hoisted by your own petard ‒ although poor Hillmann may be forgiven for not reflecting on the irony of his misfortune at this time.

The bull run expert was gored in his leg after tripping up and falling over, said ABC News. He was taken to hospital in a serious condition.

Unfortunately for Hillmann, the stab wound was dished out by the biggest bull in the entire bull run of Pamplona. It weighed in at 600kg of prime beef and was from the famous Victoriano del Rio ranch.

It is not known if Hillmann forgot the advice penned by his own hand in How to Survive the Running of the Bulls, or whether it was the book's actual advice that led him to being stuck on the sharp end of the bull's pointy appendage.

The bull run is part of the San Fermin festival and four other men suffered injuries on the same day as hapless Hillman.