Aspects of the invention include methods for treating or preventing a thromboembolic disease in a subject. In practicing methods according to certain embodiments, an amount of a low molecular weight heparin (LMWH) and a synergistically effective combination of two or more gastrointestinal epithelial barrier permeation enhancers is orally administered to a subject in a manner sufficient to treat the thromboembolic disease in the subject. Compositions and kits for practicing methods of the invention are also described.