Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
nauseous [ˈnɔːsɪəs] adj тошнотво́рный*тошнотво́рен
he's feeling nauseous его́ тошни́т
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.