reduces Nitrogen bends
25,000 ft shouldn't cause decompression sickness.
However,
(a) as the divers amongst us well know, flying (especially in the event of a decompression) following diving ... is an absolute no-no, just for this reason. Recollection suggests that a day clear in between is the general rule ?
(b) folks with lots of dental fillings may have problems with toothache
(c) folks with colds or just sinus problems may have significant problems. I recall a 25,000 ft (or thereabouts) chamber run years ago in which we had several divers along for the exposure experience. One had been diving a bit too soon before and, while he didn't end up with any joint problems, he did have a blocked eustachian and he was not a happy little camper at all ... the tears associated with the pain just about flooded the chamber. Fortunately, the flight surgeon was able to clear his ears on the way down and all was well.