A fast acting orally disintegrating film (ODF) for treatment of various medical conditions including emesis that has a simple formulation, easy to manufacture and has similar pharmacokinetic profile to currently commercially available products is provided. The ODF comprises an active pharmaceutical ingredient such as ondansetron or a pharmaceutical acceptable salt thereof in an amount of 2 to 24 mg, at least one hydrophilic film forming polymer in an amount of at least 8% by weight of the film, at least one hydrophilic film forming polymer having a molecular weight of 5000 to 50000Da, and a water soluble excipient.