Gastrointestinal distress was a term to describe an unpleasant, but not serious medical condition involving the stomach and intestine.
In 2151, Porthos suffered from mild gastrointestinal distress, caused by Jonathan Archer having fed the dog with cheese. (ENT: "Dear Doctor")
In 2152, Malcolm Reed suffered from gastrointestinal distress due to the spatial turbulences caused by a neutronic wavefront. He received a hypospray from Doctor Phlox (ENT: "The Catwalk")
In 2376, Tuvok suffered from space sickness also caused by a a neutronic wavefront with the symptoms being gastrointestinal distress and a loss of equilibrium]. (VOY: "Fair Haven")