The Collaborative International Dictionary of English v.0.48:

Nauseant \Nau"se*ant\, n. [L. nauseans, p. pr. Of nauseare.]
   (Med.)
   A substance which produces nausea; an emetic.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nauseant
    n 1: a medicine that induces nausea and vomiting [syn: emetic,
         vomit, vomitive, nauseant]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "nauseant":
   abstergent, cathartic, cleaner, cleaning agent, cleaning solvent,
   cleanser, cleansing cream, cold cream, cream, dentifrice, depurant,
   detergent, disgustingness, diuretic, emetic, enema, fetidness,
   foulness, holystone, loathsomeness, lotion, mouthwash, nastiness,
   nauseousness, obnoxiousness, odiousness, offensiveness,
   overripeness, pumice stone, purgative, purge, purifier, rancidity,
   rancidness, rankness, repugnance, repulsiveness, rinse, rottenness,
   shampoo, sickener, soap, solvent, synthetic detergent,
   tooth powder, toothpaste, vileness, vomit, vomitive, wash