Solid, particulate dicarboxylic acids may be fluid loss control agents and/or viscosifying agents for viscoelastic surfactant (VES) fluids in treatments such as well completion or stimulation in hydrocarbon recovery operations. The fluid loss control agents may include, but not be limited to, dodecanedioic acid, undecanedioic acid, decanedioic acid, azelaic acid, suberic acid, and mixtures thereof having a mesh size of from about 20 mesh to about 400 mesh (about 841 to about 38 microns). A mutual solvent or a blend of at least two alcohols subsequently added to the aqueous viscoelastic surfactant treating fluid will at least partially dissolve the solid, particulate dicarboxylic acid fluid loss control agents, and optionally also “break” or reduce the viscosity of the aqueous viscoelastic surfactant treating fluid.