ADVERSE REACTIONS: Nystatin is well tolerated even with prolonged therapy. Oral irritation and sensitization have been reported. (See PRECAUTIONS: General. ) Gastrointestinal : Diarrhea (including one case of bloody diarrhea), nausea, vomiting, gastrointestinal upset/disturbances. Dermatologic : Rash, including urticaria has been reported rarely. Stevens-Johnson syndrome has been reported very rarely. Other : Tachycardia, bronchospasm, facial swelling, and nonspecific myalgia have also been rarely reported.